Eta Carinae, Soon To Be a Local Supernova

da4 writes "Phil Plait over at Bad Astronomy has a great article about Eta Car, a star approx 7,500 light years away from us that's ready to supernova sometime Real Soon Now." Larger versions of the Hubble-Chandra image of Eta Car are available at the Chandra site. Of course when astronomers say it's "about to explode," they really mean it probably exploded 6,500 to 7,500 years ago and we're awaiting the news.

Comments

Schroedingers Nova?

[kylben]

If we never get the news, will it actually have exploded, or not?

Re:Schroedingers Nova?

[Kagura]

Way to fall into the editor's trap, trying to spur spurious discussion about whether events outside our lightcone actually happened before they intersected our lightcone. The editors may feel we need help in starting a discussion on many stories.

Re:Schroedingers Nova?

[geekoid]

Don't think you are so important that nothing happens unless you observe it, earthman.

Re:Schroedingers Nova?

[Kingrames]

You may feel a slight disturbance in the force.

Re:Schroedingers Nova?

[KudyardRipling]

First we get slammed with neutrinos. Yes, they do interact with matter. There is an underground tank of carbon tetrachloride that is used to detect neutrinos. There interact with the chlorine and change it to argon. There are detectors for argon gas that bubbles out of the liquid. So if that tank begins to fizz like seltzer, that means we're screwed. After maybe a day or so, we'll get slammed with gamma rays and other photon based emissions. As long as it is not brighter than the moon, we'll be OK. However, there will be many southern hemisphere people that won't get too much sleep for a month or so. With our luck, it will have imploded into a black hole and one of the jets will be aligned in our direction and we all will be FRIED!

Bad Astronomy?

[sczimme]

I don't know if we should take the word of someone who runs a site called 'Bad Astronomy'...

*checks TFA*

The blue part is an optical image from Hubble, and shows the bipolar lobes of gas ejected when Eta Car had a coughing fit back in the 1840s. That's 20 octillion tons of gas (20,000,000,000,000,000,000,000,000,000) it ejected at about a million miles per hour, in case you're not getting enough awesome in your diet.

I withdraw the objection. :-)

Re:Bad Astronomy?

[spun]

The Bad Astronomy site started out to debunk nutty astronomical theories, like the Electric Universe theory, or the preposterous notion that the moon landing was faked. It's a pretty decent site.

Re:Bad Astronomy?

[Anonymous Coward]

Yu talk real purrty like, you care to have some proof? perhaps something peer reviewed?

No? well then, you can just squel like a piggy.

You'all can have a magnetic field without electricity, nimrod.

Re:Bad Astronomy?

[Anonymous Coward]

Unless you count spinning charged particles as electricity, in which case you can fuck yourself and the horse you rode in on.

Re:Bad Astronomy?

[pln2bz]

Why not respond to this ...

http://www.electric-cosmos.org/Rejoinder.htm

That would be a great starting point. It was deleted from the BAUT Forum shortly after posting it because nobody was willing to be attacked. In the absence of a piñata, the theory does not exist to the people at BAUT. The EU Theorists are seeking individuals who believe that they can debate these points, but nobody's been willing to step up to the plate so far. Go figure ...

Arguing that arguments that are not peer-reviewed by mainstream astrophysicists do not count is disingenuous. People who have staked their careers on the mainstream theories will resist every attempt at disruptive paradigm shifts.

Feel free to talk to me like an adult, btw ...

Re:Bad Astronomy?

[Anonymous Coward]

Well they didn't do a very good job of that, now did they? It's obvious to most of us who made it past grade school that it was a fake. Here are just a couple of links to a good 50+ anomalies that NASA has yet to explain, but hey let's not let reason and facts get in the way here. Just go on believing what the men in white coats tell ya.

  http://www.apfn.org/apfn/moon.htm

http://www.ufos-aliens.co.uk/cosmicapollo.html

Re:Bad Astronomy?

[Anonymous Coward]

That's 20 octillion tons of gas Wouldn't that solve our dependence on foreign oil?

Re:Bad Astronomy?

[Fission86]

This conveniently ignores the fact that Einstein never even mentioned electrodynamics, except in his correspondence with (that expletive) V, and that James Clerk Maxwell demonstrated that e-fields and b-fields are inseparable.

I hate to tell you this dude, but Einstein wrote a little paper called "On the Electodynamics of Moving Bodies" perhaps you've heard of it?

Also, Maxwell never said electric fields and magnetic fields were INSEPERABLE, just that they were connected

Astrophysics continues to be the only field of science where magnetic fields are treated as if they are independent entities that can exist in the absence of electric currents and electric fields.

Also, the reason electric fields can be thought of independantly from magnetic fields, on an astrophysical scale, is that electric fields can extend infinitely from an electric monopole and magnetic fields must return to their source, which i might add has no monopole associated. Pick up an E&M book (i suggest Griffith's, it's pretty good), you might learn what Maxwell's equations actually mean.

People would be wise to consider that it is now an established fact that there exists an interstellar magnetic field whose origin remains unknown.

I'd like to see how you prove that while staying on this planet/in this solar system.

It's interesting that the site is called "Bad Astronomy" -- as if all discussion on that site is meant purely to confirm existing mainstream theories.

Every time someone starts talking about an alternate theory of physics they always have the exact same reaction when people don't believe them "oh, you're a fool for trusting the old ways, blah blah blah." There's a reason these theories are mainstream, they're testable and retestable.

Theories are not evaluated on the basis of their merit alone, but rather how well their creators can withstand a relentless series of withering attacks.

Yes, you are correct, but this is the way of doing things, since nothing can ever be absolutely proven within a finite amount of time (see universe time scale of infinity), a good bet of what is most probable is the best we can ever hope for. And a relentless attack on theories is a good way to do this, if a theory is found lacking, it might be completely wrong or just in need of a tweak. Currently the Standard Model is in one of these categories as it unifies the strong nuclear, weak nuclear and electromagnetic forces, where as gravity is unadressed. And string theory might just be in the other (it's untestable, thus cannot be proven or disproven), but that's another story all-together.

Re:Bad Astronomy?

[The Master Control P]

Eh, I'm up for some shits'n'giggles and I've got some time to pass. Of course, the fact that I disagree is certain proof that I am part of "the conspiracy" which is defined as anyone who thinks you're wrong and refuses to immediately acknowledge your obvious correctness.

Arguing that arguments that are not peer-reviewed by mainstream astrophysicists do not count is disingenuous. People who have staked their careers on the mainstream theories will resist every attempt at disruptive paradigm shifts.

Right. The guy who comes up with proof that one of our most basic theories is erroneous will be hated. He most certainly will not be one of the most celebrated scientists of all time like Einstein, and he most definitely will not win a Nobel prize for his insights. Because scientists hate discovering new and remarkable things they didn't know about before. History is full of scientists like John Levy, whose work on asteroid impacts was supressed by The Establishment even after he presented clear and convincing evidence that he was correct... No, wait, asteroid impacts are in every geology and astronomy book today.

The announcement made by the Sudbury Neutrino Observatory (SNO) that the SNO detector has the capability to determine whether solar neutrinos are changing their type en route to Earth is false on its face. There is no way that measurements made at only one end (here on Earth) of a transmission channel (that stretches from the Suns center to Earth) can reveal changes that occur farther up the channel (say, within the Sun itself, or near Mercury or Venus).

Consider a freight train that runs from New York to Chicago. We live in Chicago and are only able to observe the train as it arrives in Chicago. It pulls in with 4 freight cars, 2 tank cars, and 1 flat car. How is it possible, no matter how sophisticated our method of observation, for us to make any conclusions whatever about whether freight cars, tank cars, or flat cars have been added to or subtracted from the train at, say, Cleveland? Moreover, how is it possible to say that freight cars have turned into tank cars or flat cars along the route somewhere?

Horray for superficially plausible but completely incorrect analogies. Regardless of whatever happens to neutrinos on their way to earth, they can't simply disappear. Your analogy is simply wrong, because we do know that matter-energy was not added or lost in the neutrino stream, because neutrinos don't interact with squat. So now, we think we know what the train was like when it left. We know nothing was added or lost, yet the cars aren't what we expected. Is the logical conclusion that the neutrino waveforms changed or that it's all a giant conspiracy?

Sustained nuclear fusion using extreme heat and pressure is a Will-O-the-Wisp (literal meaning - fools fire) that has been desperately sought after for over 50 years. It has never been obtained in any laboratory. Its existence in the Suns core is nothing more than a proclaimed hypothesis. We cannot see into the Sun. We cannot observe what is occurring below the photosphere. The Electric Sun model does indeed include the probability that empirically confirmed nuclear fusion is occurring near the surface of the Sun.

Let me make sure I've got this right... you're comparing the conditions in experimental fusion reactors to those which exist in the core of a star? And then saying that since our fusion reactors don't work, starfusion doesn't work? I'm afraid there are some minor differences, like the fact that the core of a star is compacted to twenty times the density of lead by gravity. There's also the basic fact that energy loss is proportional to area and fusion output to volume, which puts our tiny reactors at a slight disadvantage.

Either you truly don't know these things about fusion physics, which casts doubt on how much else you don't know, or you are intentionally ignoring them.

Re:Bad Astronomy?

[RespekMyAthorati]

It's obvious to most of us who made it past grade school that it was a fake.

It's obvious to anyone who actually paid attention in grade school that these "anomalies" have all been explained, although most of them never needed to be. Only an idiot would have any trouble seeing through "anomalies" like "the images are too perfect" (they are far from perfect) or "who took the the picture of Neil Armstrong on the ladder" (the camera was mounted on the lander's base).

Lord, deliver us from morons like you.

Re:Bad Astronomy?

[the_lesser_gatsby]

...Chicago. It pulls in with 4 freight cars, 2 tank cars, and 1 flat car. How is it possible, no matter how sophisticated our method of observation, for us to make any conclusions whatever about whether freight cars, tank cars, or flat cars have been added to or subtracted from the train at, say, Cleveland? Moreover, how is it possible to say that freight cars have turned into tank cars or flat cars along the route somewhere?

Horray for superficially plausible but completely incorrect analogies.

Not only incorrect but not even plausible. It's perfectly reasonable to imagine subjecting the freight car couplings to "sophisticated" materials analysis to determine when they were last stressed and by how much.

The arguments on that page boil down to "I don't understand how that can work, therefore it can't be correct".

Re:Bad Astronomy?

[fatphil]

It's just a shame that in the middle of debunking things that are just plain wrong, he can make assertions that are just plain wrong too.

See http://www.badastronomy.com/bad/misc/grandcen.html for an example of him making _exactly_ the same kind of mistake that he critices fools for. Sure, like all supposedly good science resources, he's constrianed by trying to simplify his ideas so that they'd be understood by the intended audience, but in this particular case, his example was not just wrong, but unnecessary.

Re:Bad Astronomy?

[fatphil]

"neutrinos don't interact with squat. "

Did they interact with your detector?

Never try to simplify physics to explain it to someone stupid, you only make it wrong.

Re:Bad Astronomy?

[Aenoxi]

OK, I'll bite - I read the article you linked to, and found it pretty convincing in a non-astronomer-common-sense sort of way. I'd be genuinely interested to understand what the mistake is if you've got the time to explain? Cheers!

Re:Bad Astronomy?

[Kashgarinn]

I'm probably digressing a bit.. I'd like to ask a few simple question, not being much up to date on science.

1) There are 4 different discrete powers of attraction, right? Gravity (the reason why you can walk on planet earth), electro-magnetism (the reason you can use a computer), weak nuclear forces (the reason you can use a mouse) and strong nuclear forces (the reason why you're here at all).. right? By discrete I mean they completely ignore one another, you can't increase a magnetic force between 2 objects to change the force of gravity between them, same with gravity and weak nuclear forces, and electro-magnetism and strong nuclear forces and all that.. right?

2) what does the theory of electro-universe-thingy try to solve? What is it about the normal model which is failing to explain which electro universe successfully explains?

I mean models are just that.. models.. and the only 2 reasons models are useful if they enlighten us to our current situation (as in "Using our model based on research, blackholes are out there, and our solarsystem could be sucked into a passing blackhole") or help us (as in "based on research, and wanting to survive, we built this model to show how we could avoid getting sucked into a passing blackhole")

Or am I being silly?

K.

Re:Bad Astronomy?

[pln2bz]

Right. The guy who comes up with proof that one of our most basic theories is erroneous will be hated. He most certainly will not be one of the most celebrated scientists of all time like Einstein, and he most definitely will not win a Nobel prize for his insights. Because scientists hate discovering new and remarkable things they didn't know about before. History is full of scientists like John Levy, whose work on asteroid impacts was supressed by The Establishment even after he presented clear and convincing evidence that he was correct... No, wait, asteroid impacts are in every geology and astronomy book today.

There is a very long list of catastrophists and EU Theorists who have been shunned by the mainstream and made to pay a price for their beliefs. You bring up Einsten. Surely, you must be aware of the treatment that Einstein's friend, Velikovksy, received by Carl Sagan. Not everything that Velikovsky said really hit the mark, but his theory that dramatic planetary rearrangements can occur will eventually become accepted as fact. Hannes Alfven was treated as an outsider for his beliefs despite winning the Nobel Physics prize. Dwardu Cardona will certainly be treated the same way as people come to the realization of what he's accomplished in his book, God Star. There are plasma physicists at prestigious institutions within this country that are afraid to admit that they support EU Theory 100% because they will LOSE THEIR JOBS if they do so. I hope that you know the story of Halton Arp -- who lost his telescope time for believing that quasars were being ejected from the centers of spiral galaxies -- a fact which appears to not be going away any time soon because a newer peer-reviewed paper has come out with a fresh set of statistics to support his theory. But Halton Arp has to continue doing his work now in another country.

I think you will find that there is a very large barrier to publication of EU ideas within mainstream peer-reviewed journals if you care to look into it. Many people don't do the research and then try to cast EU advocates as conspiracy nuts when in fact nobody's alleging any sort of secret conspiracy. There's no need for a conspiracy. It's just psychology. People tie their belief systems to their egos. If you attack somebody's belief system, then they will interpret it as if you are physically attacking them, and they will defend their ideas quite bitterly. People here on Slashdot tend to be the worst offenders because they also tend to be technology advocates. People who know a lot about the advanced state of our technology will oftentimes infer that our interpretive sciences are just as sophisticated as our technologies. Technology advocates (I used to fall into this category myself) prefer to believe that we are masters of our own universe. Believing that we understand more than we do about the space sciences naturally follows from this desire.

So now, we think we know what the train was like when it left.

And that, right there, is the problem, for if you can't measure that, then you lack the data to draw conclusions.

Re:Bad Astronomy?

[armareum]

The arguments on that page boil down to "I don't understand how that can work, therefore it can't be correct".

Heh, that's how most people argue against the theory of evolution:

"I can't even imagine one single way that B could have evolved from A. Therefore it was designed."

- Somehow admitting you don't have enough creativity or imagination is proof of your arguement.

Re:Bad Astronomy?

[pln2bz]

The arguments on that page boil down to "I don't understand how that can work, therefore it can't be correct".

It would be nice to see a technical explanation for why Don Scott is wrong. The theorists continue to wait.

It was only a few months ago that people pointed to Tim Thompson's arguments against The Electric Sun Theory as proof that EU Theory was bogus. Now that the EU Theorists have responded to that piece, there has been no serious challenge to his response. It's been a few months now. If this is so bogus, what is causing the delay?

???

Re:Bad Astronomy?

[Tzunamii]

I believe Dr. Scott was pointing out the fact that we cannot see into the sun to gather data to compare anything to.

We can speculate and attempt to deduce, but using the empirical method, can it even satisfy the requirements to bring it from idea to hypothesis? (Observation)
That being the case, how do we know the core of a star is compacted 20 times the density of lead?
Have we observed the core of a star?

Have we done real experiments to reach these conclusions?
If anything below the photosphere cant be observed, wouldn't any deductions made be simply guesses?
It just makes sense to me that reguardless of the quality of our tiny reactors, if their data is bieng compared to what we ~guess~ is going on inside a star.
It must be difficult falsifying an idea if the information you need to do so is out of reach, & what good is a hypothesis if you cant falsify it.
I don't ask these things to be confrontational. I've been watching this debate for a bit, and want to know.

It would help if links with real answers were included in these posts.
Thankyou

Re:Bad Astronomy?

[Anonymous Coward]

This attempt to prop up fatally flawed dogma is on par for the course. People who have spent decades believing in a thing are loathe to admit they were wrong. Myself, I love to admit when I have made a mistake or once believed something that was wrong, it is the only proof to others that I can learn. If only the author of the post above was so concerned with learning instead of simply memorizing stories and flatly and baldly denying anything that doesn't conform to those fables.

thanks

[stoolpigeon]

Of course when astronomers say it's "about to explode," they really mean it probably exploded 6,500 to 7,500 years ago and we're awaiting the news.
 
could you clear up that 'sun rise' and 'sun set' thing for me as well?

Re:thanks

[IcyNeko]

Sunrise, sunset. Sunrise, sunset. Swiftly flow the days. Seedlings turn overnight to sunflowers, blossoming even as we gaze.

I hope this clears up any further questions.

Re:thanks

[HTH NE1]

Of course when astronomers say it's "about to explode," they really mean it probably exploded 6,500 to 7,500 years ago and we're awaiting the news.

could you clear up that 'sun rise' and 'sun set' thing for me as well?

How about this: even though this expected supernova happened thousands of years ago, for all causal purposes, it won't have any effect upon us until we can see it. After all, the speed of light is really just the speed of causality.

So, in a local causal sense, it hasn't happened yet. The distance just means that if we thought to have any influence on it before it happens here, we'd have to have done something thousands of years ago or longer to exert a causal influence.

Re:thanks

[mabhatter654]

What happens if Schroedinger's Cat is is a box between the earth and this supernova and could be destroyed by the radiation wave?

On a side note for all those young earth creationists out there, perhaps the event that will destroy the world has already happened x thousand light years away at the exact moment of creation and we just haven't figured it out yet!

Re:thanks

[w1d3]

that is actually very simple..
while(1){
    sun(rise);
    sleep(60*60*12-daily_change);
    sun(set);
    sleep(60*60*12+daily_change);
}

Re:thanks

[jc42]

could you clear up that 'sun rise' and 'sun set' thing for me as well?

Sure thing. They are optical illusions. The sun actual moves across the sky much more slowly, taking a year to make the fulls circle. The Earth, however, is rotating once per day. This causes the apparent motion of the sun across the sky once per day.

Actually, the slow, year-long motion of the sun across the sky is also an optical illusion. In reality, the Earth moves in a nearly circular orbit around the sun, taking a year for each orbit. From our viewpoint, this has the effect of making the stars appear to shift by about a degree each day, but it's actually because we've moved about a degree along our orbit.

However, the sun is actually moving in an orbit around the center of the Milky Way galaxy, pulling the Earth along with it. But that orbit takes around 230 million years, so the motion isn't detectable to our eyes, and may be ignored in explaining apparent motion of the sun.

HTH. HAND.

Re:thanks

[catman]

"Cheer up, Mrs Brown -"

" ... let's hope that there's intelligent life somewhere out in space,
'cause there's bugger-all down here on Earth!"

Re:thanks

[Plutonite]

Ah, an I-can-shock-you post. Can I join in?

Hows this: The word "happened yet" is irrelevant unless you are talking about a specific frame of reference to which the event relates, so although the fact that any effect (including the visual) only "happens to us" at the speed of light, the event has actually occurred for other bodies whose motion can be defined in relation to ours... i.e we can calculate what happens even before it happens to us, we don't have to wait for anything.

Now add spooky-action-at-a-distance, alternative realism and some freaky math and we have a real I-can-shock-you post.

Re:thanks

[jc42]

Well, I was tempted to end with that. But I decided it would be too unsubtle, and I should leave it to the readers' imagination. Guess it worked.

Re:thanks

[HTH NE1]

Even then, the observation of other objects reacting to an event cannot occur until we have an opportunity to observe the event. Anticipation is not a reaction causually speaking. What we have is anticipation of an event due to recognition of other events that typically (or rather predictably) precede a nova event. For us to observe phenomena that occur after a nova before the nova itself, that phenomena by definition would have to be FTL.

The funky stuff happens in the quantum state where phenomena don't happen unless they are observed. Events that occur and affect us without observation only arise from quantum events that manage to be observed in a manner that cannot be ignored.

What we are discovering is that we can cause events that will not occur unless they are observed. Perhaps then the next definition of magic is the ability to observe the right quantum effects which occur all the time unobserved to cause a non-ignorable phenomena to manifest itself.

Don't hold your breath

[MarsDefenseMinister]

We could be waiting to see this supernova theoretically about as long as the pyramids have been standing over the sands of Egypt.

Re:Don't hold your breath

[ozzee]

We could be waiting to see this supernova theoretically about as long as the pyramids have been standing over the sands of Egypt.

If that is the case, Eta C. should already have gone supernova. We just can't see it yet.

Re:Don't hold your breath

[Control Group]

If that is the case, Eta C. should already have gone supernova. We just can't see it yet.

Which is an interesting statement, really, since it presupposes some sort of universal timeline on which it has "already" gone supernova. When in fact, there is no universal synchronicity.

Re:Don't hold your breath

[ozzee]

Which is an interesting statement, really, since it presupposes some sort of universal timeline on which it has "already" gone supernova. When in fact, there is no universal synchronicity.

Does that mean that cat I ran over last night in my car was not necessarily born yet so I didn't really run over it ? Phew, I was having a bit of a guilt trip....

Re:Don't hold your breath

[IWannaBeAnAC]

Argh, I was going to moderate this thread, but when I saw this post I felt I should reply instead.

Eta C surely has gone supernova already. General relativity tells us that the passage of time depends on your movements in space, but it doesn't forbit the presence of some 'special' reference frame in which one can consistently give an age on events that happen in the universe. That special reference frame would be the one based on the center of the universe - in effect, the center of mass frame. But even without such a special frame, we can certainly give a precise timeline between any two events no matter how separated they are or how they move. General relativity allows the exact calculation, it just won't be a constant timeline with time moving at the same rate for all observers.

For the case of Eta C, it is located at a distance of 7500 lightyears away, so the light we see from it now left Eta C 7500 years ago. Since we will surely see it go supernova sometime within the next 1000 years, there is no doubt at all that Eta C went supernova sometime between 6500 and 7500 years ago. General relativity doesn't even come into it, it is already clear just from the finite velocity of light.

Re:Don't hold your breath

[Anonymous Coward]

No, causality is always maintained. The speed of light represents the *boundaries* of the time-scale, but not necessarily the scale itself. You can always say if two events are time-like or space-like separated.

Re:Don't hold your breath

[MarsDefenseMinister]

How do you know Eta Carinae went supernova during that specific time? We're seeing as it existed 7500 years ago. We're not sure, from what we can see with our eyes right now, that it doesn't depict a supernova 10,000 years from exploding. If that's true, then we'll see the supernova 17,500 years from now.

Re:Don't hold your breath

[Ambitwistor]

There is no "center of the universe" or "center of mass of the universe", but there is still a "special" reference frame: the one in which the universe is isotropic (ignoring small anisotropies): it's the one in which the cosmic background radiation would not be blue/redshifted in opposite directions.

That being said, general relativity is largely irrelevant on non-cosmological scales for these purposes.

Re:Don't hold your breath

[Planesdragon]

When in fact, there is no universal synchronicity.

Just because we're not able to perceive or measure it, or that it's not useful on a relativistic scale, doesn't mean it's doesn't exist.

"From the local frame of the universe as a whole" is a fine theoretical basis to correct the "reality isn't really real" line that relativity and quantum mechanics lead freshmen down.

Re:Don't hold your breath

[IWannaBeAnAC]

You should RTFA. It is almost at the end of the stellar lifecycle, and has already used up all of its hydrogen. If we don't see it go nova sometime within the next 1000 years, then our theories of stellar evolution are seriously f*cked.

Re:Don't hold your breath

[IWannaBeAnAC]

Are you just nitpicking? If momentum has been conserved since the big bang, then there is surely a center of mass frame, and also a center of mass. The frame in which the cosmic background is isotropic might be a better definition, because it would be well-defined even in cases where the center of mass is not (say, if the universe is finite but has a non-trivial topology), but I'd like to know your reasoning for asserting that this is indeed the case [ie. that the center of mass of the universe is not well defined].

Re:Don't hold your breath

[Ambitwistor]

Are you just nitpicking? No.

If momentum has been conserved since the big bang, then there is surely a center of mass frame, and also a center of mass. Where do you think the center of mass of the universe is located? Consider the most popular geometries, planar and spherical. Where is the center of an infinite plane? Where is the center of a spherical surface? (Note: this is not "where is the center of a sphere", but rather, "which point on the surface of a sphere is its center"?) Both are ill defined: there is no unique point which is the center of a plane or a spherical surface.

The cosmic background isotropic frame is something analogous to a "center of momentum" frame, although it is not a "center of mass" frame. (Nitpicking, momentum is not globally conserved in general relativity, either, nor is energy; see here, noting the discussion of the unification of energy and momentum. Nevertheless, you can pick a particular frame in which there is spatial translation invariance — the cosmic background isotropic frame — which is what gives rise to momentum conservation in flat spacetime. In that sense, you can consider momentum to be conserved in that frame.)

Re:Don't hold your breath

[ZombieWomble]

Didn't you state the reason yourself? I was under the impression (I keep up with cosmology purely on a popular science level, so it's quite possible I'm not up to date) that most theories of the universe involved a finite universe, but one which lacks spatial boundaries in our common 3 dimensions, which would then ruin any attempt to explicitly define a center of mass.

Re:Don't hold your breath

[IWannaBeAnAC]

Right - whether the center of mass is well defined depends on the geometry, I agree with that. But there certainly are geometries where it makes sense, although your example of a finite universe with positive curvature is not one of them. The infinite plane though, is not so clear. Is the universe really infinite, as opposed to finite but possibly curved? For another possible geometry, a Euclidean universe could certainly have a well-defined center of mass.

Re:Don't hold your breath

[Mathness]

That special reference frame would be the one based on the center of the universe - in effect, the center of mass frame. Hey, no need for Yo momma jokes. :p

Re:Don't hold your breath

[Dogtanian]

But even without such a special frame, we can certainly give a precise timeline between any two events no matter how separated they are or how they move. I understood that this wasn't always the case.

Re:Don't hold your breath

[Ambitwistor]

The infinite plane though, is not so clear. Ask a mathematician. An infinite plane has no center. It is translationally invariant: every point is like every other.

Is the universe really infinite, as opposed to finite but possibly curved? Inflation implies that it's either infinite and flat, or finite but so large that its curvature is unnoticeable. Observationally, it's very close to flat, but we can't prove it really is infinite and flat.

For another possible geometry, a Euclidean universe could certainly have a well-defined center of mass. Not an infinite and homogeneous Euclidean universe (that's the same as a plane). Newton wrote about that.

Re:Don't hold your breath

[Kristoph]

I know it's slashdot but if you read the article ...

Eta Car is ticking bomb. It could go off tonight, or in the year 3000 (did Futurama ever cover this?), but it won't be much longer than that.

]{

Re:Don't hold your breath

[MarsDefenseMinister]

I have read the article. Been reading about eta car for the last 15 years or so.

Are the theories seriously fucked if there's an error of 7000 years over the lifespan of millions? (for that type of star)?

Re:Don't hold your breath

[IWannaBeAnAC]

Sorry, I should have said: with respect to a particular observer, we can always give a precise timeline. For a different observer the timeline might be different (eg, some events might be seen to occur in a different order), but it is still well defined.

Re:Don't hold your breath

[IWannaBeAnAC]

Whoa, hang on a minute. What about the big bang? Doesn't that imply that the universe cannot be infinite and translationally invariant?

Re:Don't hold your breath

[IWannaBeAnAC]

The timespan isn't millions of years; the time since the star started shedding nitrogen is only a few hundred years (? I can't be bothered going back to the article - but anyway it is much less than millions).

for a slightly sick analogy, predicting the lifetime of a child at birth is hard to do with any accuracy. Predicting the lifetime of someone dying of cancer is much easier ;-)

Re:Don't hold your breath

[Ambitwistor]

The Big Bang implies that spacetime can't be infinite and translationally invariant. Space, however, can be.

Re:Don't hold your breath

[maxume]

I don't expect to wait much more than 60 more years, maybe 70 if I am really lucky.

Re:Don't hold your breath

[kmac06]

I disagree. It surely is not in our future lightcone, but it also is surely not in our past lightcone. So you can't say whether it's happened or not!

Re:Don't hold your breath

[IWannaBeAnAC]

Yes, it is not in our past lightcone in exactly the same way that, if you were currently on Alpha Centauri, this slashdot thread would not be in your past lightcone. That doesn't change the fact that you would not be able to affect the outcome of whether I hit 'submit' or not. Sure, you would not be able to prove that the event has occurred, not for another year, but so what? It is no less certain than any other prediction of a natural event.

Re:Don't hold your breath

[MarsDefenseMinister]

By millions I was talking about the total lifespan of the star.

But it's cool that eta car is all the way up to nitrogen. When does it blow up? After it's burned all the way down to iron?

Re:Don't hold your breath

[IWannaBeAnAC]

Huh what? I don't know what it means to talk about space in the absence of matter, I can't see how it can even be defined. For sure the big bang has broken the symmetry of space (if there was such a thing as space independent of the big bang), so I really don't understand your response. You refer to 'space' as distinct from 'spacetime' ? Are you referring to some kind of broken Lorentz invariance, where space is translationally invariant but spacetime is not? I don't understand how that can be, it would imply that the universe is evolving in the same way at all locations in space, which then implies (as far as I can tell, in my slightly drunk state) that there would be a preferred reference frame in which this takes place (otherwise the distinction between space vs spacetime could not be made).

Re:Don't hold your breath

[kmac06]

In some other (but perfectly valid) reference frame, the star exploded after you hit submit.

Re:Don't hold your breath

[pionzypher]

Correct, core collapse supernovae go when they hit iron.

Re:Don't hold your breath

[fatphil]

"we will surely see it go supernova sometime within the next 1000 years"

There's no 'surely' about it. Stop spreading misinformation.

Re:Don't hold your breath

[fatphil]

Are you confusing "it won't be much longer than that" with "it cannot be any longer than that"?

Re:Don't hold your breath

[fatphil]

Wrong. You need an inertial reference frame. Not all observers are inertial reference frames. See the twin paradox.

Re:Don't hold your breath

[IWannaBeAnAC]

I don't get what you're saying here. Even with the twins `paradox', for each twin separately, there is surely a consistent timeline. Moreover, if we have the timeline for one twin, it is possible to calculate that the timeline would be for the other (or any other observer).

Re:Don't hold your breath

[IWannaBeAnAC]

Can you elaborate? If we don't see it go nova within the next 1000 years, then there is something badly wrong with current theories of stellar evolution - which would probably mean there is something wrong with our theories of nuclear fission - but that is a subject that is pretty well understood (at least by nuclear physicists!).

Re:Don't hold your breath

[IWannaBeAnAC]

No, the star exploded at just a single point in spacetime. If you were not at the same location at the same time, then it is too late to do anything about it. An observer located around 1000 light-years closer to Eta C would be seeing the star explode right about now. But that doesn't mean that the star is exploding at that moment in that reference frame, it just means you are seeing the light hit you from the event 6,500 years ago.

Re:Don't hold your breath

[Ambitwistor]

I don't know what it means to talk about space in the absence of matter, I can't see how it can even be defined. General relativity has no problem defining space in the absence of matter, and there are plenty of vacuum solutions of the Einstein field equation (Minkowski spacetime, the Schwarzschild solution, gravitational geons, a universe filled with gravitational waves, etc.). I don't know why the definition of space should have anything to do with matter; you can certainly define a geometric relationship between different points in vacuum.

For sure the big bang has broken the symmetry of space (if there was such a thing as space independent of the big bang), so I really don't understand your response. Of course space is not perfectly symmetric (there are stars and planets scattered everywhere), but on large scales, it is very close to homogeneous and isotropic.

You refer to 'space' as distinct from 'spacetime' ? There are infinitely many ways of slicing (foliating) "spacetime" into "space" and "time". Cosmologically, there is a "special" way of doing so, which is to choose the slicing that leaves space homogeneous and isotropic (the aforementioned CMBR-isotropic frame). The laws of physics themselves do not prefer such a slicing; it is a particular property of the homogeneous/isotropic Big Bang spacetimes.

Are you referring to some kind of broken Lorentz invariance, where space is translationally invariant but spacetime is not? Yes. Every curved spacetime breaks Lorentz invariance, which only holds exactly in Minkowski spacetime. (All spacetimes have local Lorentz invariance though, which is a fancy way of saying that spacetime looks flat if you look closely enough — ignoring quantum effects, of course.)

I don't understand how that can be, it would imply that the universe is evolving in the same way at all locations in space, which then implies (as far as I can tell, in my slightly drunk state) that there would be a preferred reference frame in which this takes place (otherwise the distinction between space vs spacetime could not be made). Yes, that's correct. The Friedmann-LeMaitre-Walker-Robinson (FLRW) spacetimes are homogeneous and isotropic, meaning that they have spatial symmetry that singles out a unique way of slicing spacetime into space-and-time. In that frame, the universe evolves the same way at all locations.

As I said, this is not exactly true: some locations have galaxies and some don't. But on the largest scales, you can treat the universe as a uniform noninteracting "gas" or "dust", with approximately the same density everywhere, expanding everywhere at the same rate. (These FLRW models neglect fancier inflation type theories in which specific patches of space inflate and others don't, as well as other inhomogeneous and anisotropic cosmologies. The observable universe, however, appears to be well approximated by the FLRW models.)

Also, as I mentioned before, the existence of such a frame does not make it a "preferred" frame in the sense of violating the relativity principle: the laws of physics themselves do not single out such a frame, and there are plenty of solutions of the Einstein field equation which do not have such a frame. Only these very symmetric solutions do (and, of course, our universe does not exactly possess this symmetry anyway; it's just an approximation, albeit a good one).

Re:Don't hold your breath

[internic]

In the standard cosmological model, the Friedman-Robertson-Walker model, the Universe is isotropic and homogeneous (on large scales). In this model the Universe has no edges and nothing that can meaningfully be called a center. If we take the case where the Universe has a constant, positive spacial curvature, in that model at any instant in time the universe is a hypersphere. If we ignore one of the spacial dimensions (so that things are easier to visualize), then at each instant in time the space that makes up the Universe has the geometry of the surface of a sphere. So, if you imagine that our Universe is the surface of this sphere, the expansion of the Universe is exactly analogous to inflating the sphere like it's a balloon. No point in space (meaning, on the surface of the sphere) is the center of this expansion. In fact, if you are at any point on the sphere, it appears as though everything is moving away from you as though you're at the center.

Our Universe is very close to being flat, and is most likely slightly negatively curved. This is a lot harder to visualize, since we can't model them with a nice closed 2D-surface sitting in 3D space. In any case, taking the case of flat space, the Freedman-Robertson-Walker model tells us that space is basically an infinite plane (again, no edges and nothing you can meaningfully call a center). In this case, the best way to imagine the expansion of space is to imagine letting raisin bread rise. The raisins are like the galaxies in space. When the bread rises, each piece of dough expands, so the distances between all the raisins expand uniformly (ideally). For any particular raisin, it appears that all raisins are moving away from it and it is the center of the expansion. If the bread had no edges, like space, there'd be no meaningful way to say the expansion had a center.

If we imagine videotaping this expansion in either case, then when we run the recording backward things will get closer and closer together until eventually they're right on top of one another. That instant is called the big bang. Just as the expansion looks the same at every point in space, this instant looks the same at every point in space. In the case of the spherical universe, this happens when the radius of the sphere has decreased to zero. Thus, the big bang didn't happen at any particular point in space. It happened everywhere in space simultaneously. Or, if you like, you could say that at the instant of the big bang all points in space were right on top of one another, so talking about different points in space doesn't even make any sense in that context.

Re:Don't hold your breath

[IWannaBeAnAC]

Thanks, that mostly makes sense. Except, doesn't the universe have a well-defined diameter, which is given by the age of the universe since the big bang?

Re:Don't hold your breath

[IWannaBeAnAC]

Right, but you are talking about models. Models are great because you can actually calculate things using them. But a model is not going to correspond to reality in every possible detail (otherwise it wouldn't be a model - it would be a theorem!). I don't care whether it is convenient to model the universe as an infinite (nearly) flat plane or not, I'm asking whether it is an infinite (nearly) flat plane. You seem to be confusing the case of an infinite universe with that of a finite and closed curved universe, or maybe your terminology is just confusing me. If the universe is positively curved, then it is surely also finite. To take your example of reduced dimensions and embedding the 2D surface of a sphere in 3-space, the sphere still has a well-defined radius. The 2-sphere is not, in any sense of the word, infinite. Even if it is negatively curved, then it can still be finite, in the sense of having a well-defined maximum distance between two points that were initially close to each other at the big bang.

Re:Don't hold your breath

[fatphil]

You think that the twin who heads off with velocity V and comes back with velocity -V defines an intertial reference frame?

Did you not notice the change in velocity?

Re:Don't hold your breath

[fatphil]

The last figure I saw from NASA (linked to from the previous /. story about it) was that EC was *likely* to supernova within 3000 years. It's I'm sure defined by a statistical model, and a PDF. PDFs have tails.

Re:Don't hold your breath

[IWannaBeAnAC]

You think that the twin who heads off with velocity V and comes back with velocity -V defines an intertial reference frame?

No, I can't see anything in my post that even suggests I think there is an inertial frame for the two twins. What makes you think that? I said "Even with the twins `paradox', for each twin separately, there is surely a consistent timeline." That is, for each twin separately, I made no claim that there would be a consistent common timeline for the two twins!

All I am saying is that one twin would be able to use general relativity to calculate the timeline from the point of view of the other twin. Isn't that in fact obvious?

Re:Don't hold your breath

[IWannaBeAnAC]

Well, I'm not an astrophysicist - all I can do is quote from people who are. The current article says

So Eta Car is ticking bomb. It could go off tonight, or in the year 3000 (did Futurama ever cover this?), but it wont be much longer than that.

So, maybe saying it will happen within 1000 years is a stronger statement than is warranted, but do you really care?

Re:Don't hold your breath

[Ambitwistor]

If space is finite, you can define its size, which can be interpreted as a "diameter" if it is (hyper)spherical.

However, this size is not given by the age of the universe — that would only hold if the universe expanded at a constant speed equal to the speed of light, giving a linear relationship between size and age, which is not the case.

Re:Don't hold your breath

[IWannaBeAnAC]

Of course, the universe doesn't need to be expanding at the speed of light, or even at a constant speed, for there to be a functional relationship between the age of the universe and the diameter. What about Hubble's Law?

Re:Don't hold your breath

[fatphil]

If you're not in an inertial reference frame, then your phrase "precise timeline" isn't particularly meaningful. If it means anything at all it's vapid.

Imagine the travelling twin (at c/2) is sent monthy food parcels (at 3c/4). On his way out he receives those at one frequency (one every 3 months), but on the way home he receives them at a different frequency (one every 18 days). If he tears off pages of his calender based on those food parcels, he's suddenly going to have trouble when he changes direction. I view that as imprecision in his timeline. All clocks in all inertial frames are clocks in all other intertial frames. That I view as having precision in your timeline.

If all you meant was "all signals that arrive at observer's time t arrive at observer's time t", then I guess all I can do is shrug and say "yeah, whatever".

Re:Don't hold your breath

[IWannaBeAnAC]

You seem to be confusing 'non-uniform' with 'imprecise'. Of course, if the twin is receiving food parcels that were sent from Earth at regular times, then he will actually get them at irregular intervals because of his motion. You call this 'imprecise', but that isn't good terminology: if he keeps a record of his motion via an accelerometer on his spaceship, then he can calculate precisely when the next food parcel will arrive, based on his motions relative to the Earth. You certainly don't need to be in an inertial frame to do this, you just need to be good at solving horrendous non-linear differential equations ;-)

Re:Don't hold your breath

[Ambitwistor]

Of course, the universe doesn't need to be expanding at the speed of light, or even at a constant speed, for there to be a functional relationship between the age of the universe and the diameter. Of course. Expansion at the speed of light is only necessary for the "radius" (in lightyears) to equal the age (in years). But in general, there is always some (nonlinear) relationship between size and age.

What about Hubble's Law? Hubble's law is an approximation. For an exact solution you need to look at the Friedmann equation.

Re:Don't hold your breath

[internic]

Right, but you are talking about models. Models are great because you can actually calculate things using them. But a model is not going to correspond to reality in every possible detail (otherwise it wouldn't be a model - it would be a theorem!). I don't care whether it is convenient to model the universe as an infinite (nearly) flat plane or not, I'm asking whether it is an infinite (nearly) flat plane.

Models, theories, are what science deals in. In reality we can never say exactly what nature is like, we can only offer the model that best corresponds to the data we have and entails the fewest or simplest assumptions. Our cosmological models are based on General Relativity and the assumptions that the Universe is homogeneous and isotropic if you look at it on a large enough scale. Our models for the Universe do not have edges because GR doesn't really provide for the existence of edges, we don't really have any idea what that would mean or how it would behave, and we have never observed any such thing. Therefore, Occam's razor mandates that our models have no edges. It require additional, unnecessary assumptions.

You seem to be confusing the case of an infinite universe with that of a finite and closed curved universe, or maybe your terminology is just confusing me. If the universe is positively curved, then it is surely also finite.

I'm not sure exactly what part of my earlier post confused you, so let me restate as clearly as I can. The Friedman-Robertson-Walker model of the Universe (which proceeds from GR and the assumptions mentioned above) says that at any instant the spacial extent of the universe is a 3D hypersurface of constant curvature (and no edges). If it has positive curvature, then it must be a hypersphere, which certainly does have a finite size. If it has negative curvature, then it is infinite in extent (it is the 3D analog of the pseudosphere). If it is flat, then the Universe is simple a Euclidean plane (hyperplane, if you like) which is, again, infinite. One can also think of this as the limiting case of the spherical universe where the radius of the sphere is taken to infinity.

And as I said before, there is no unique center to the Universe or center to its expansion in the FRW model, regardless of the spacial curvature.

Re:Don't hold your breath

[Anonymous Coward]

There's no 'surely' about it. Stop spreading misinformation. Since you're being a bit pedantic here, check out definition no. 3 for the word, surely. Language has moved on from your Fowler-centric viewpoint, and there's surely nothing wrong with the original poster using surely in that context :)

Re:Don't hold your breath

[Ambitwistor]

That's a pretty juvenile vendetta there, mod. Did you really blow all your mod points in a pointless exercise to downgrade as many of my posts as possible? Did you really think anyone is going to not read those posts because of it? Or that my karma is going to be significantly affected?

Re:Don't hold your breath

[xaonon]

General relativity tells us that the passage of time depends on your movements in space, but it doesn't forbit the presence of some 'special' reference frame in which one can consistently give an age on events that happen in the universe. That special reference frame would be the one based on the center of the universe - in effect, the center of mass frame. Actually, that's exactly what it forbids. There are no privilaged frames of reference. It is often convenient to use as a baseline the reference frame which is stationary with respect to the cosmic microwave background (the co-moving frame), but this is merely a useful convention. It has no special physical significance.

Re:Don't hold your breath

[IWannaBeAnAC]

What? Of course it has special physical significance, it is the uniquely defined frame that is stationary with respect to the cosmic microwave background! Just because it doesn't appear as a fundamental entity in relativity, but is instead an emergent property of our particular cosmology, doesn't make it any less special. In some sense, that makes it even more special: in some other universe, different to ours but still allowed by general relativity, such a frame might not exist!

Re:Don't hold your breath

[xaonon]

What I mean is, it's not special in terms of physical law. It's certainly unique and useful, but there is nothing in physics that makes that frame of reference fundamentally different than any other. It's merely convenient.

Re:Don't hold your breath

[IWannaBeAnAC]

Well, we could go back and forth on this all day. But unless I was asleep while the rest of the class learned the definition of 'unique', I would say that being 'unique' is exactly what makes that frame of reference special. Note that the word word I have consistently used is 'special', I have never referred to it as 'fundamentally different', you are trying to put words into my mouth. Indeed, I even agree with you that

it doesn't appear as a fundamental entity in relativity

You started off saying I was wrong:

IWannaBeAnAc: General relativity tells us that the passage of time depends on your movements in space, but it doesn't forbit the presence of some 'special' reference frame...

xaonon: Actually, that's exactly what it forbids.

You now seem to be backing away from that statement and instead simply saying that "there is nothing in physics that makes that frame of reference fundamentally different than any other". But that is still not correct. The fact that such a reference frame exists is not implied by general relativity, but is apparently a consequence of our particular cosmology. Whether it is some random chance the universe ended up this way (which is what string theory rather vacuously implies), or whether it is a natural consequence of some deeper physical law, is an interesting question. But the fact that it exists is most definitely a special property of our universe.

Gamma Rays

[turgid]

So, do I need to build a lead-lined concrete bunker in my garden?

Re:Gamma Rays

[kungfoofairy]

According to TFA, it's tilted 40 degrees away from us so we won't get hit.

Re:Gamma Rays

[drinkypoo]

According to TFA, it's tilted 40 degrees away from us so we won't get hit.

I don't understand that. Aren't stars more or less spherical? Or is this some kind of vindication for the radial explosion added to the death star in the remake?

Re:Gamma Rays

[niceone]

So, do I need to build a lead-lined concrete bunker in my garden?

You don't have a lead-lined bunker in your garden already? You must be new around here.

Re:Gamma Rays

[PieSquared]

Stars rotate on an axis. I'm not an astrophysicist, but I'd assume that most of the radiation and gasses would go either in the direction of the axis or in the plane perpendicular to it. I mean, there is a *huge* amount of angular momentum that has to be preserved when you consider mass and the speed of rotation.

So yea, kinda like the death star explosion in the remake. Or maybe perpendicular to that. Once again, not an astrophysicist.

Re:Gamma Rays

[spun]

I'm no astrophysicist, but from what I understand, because of the magnetic fields most of the dangerous crap exits from the poles.

Re:Gamma Rays

[Anonymous Coward]

What's the 'kill zone' for a nova pointed at you? I thought I remembered hearing 10,000 light years someplace, but I can't recall for sure. Any Astro guys out there know?

Re:Gamma Rays

[kenaaker]

The lobes in the picture show the path followed by the material from previous outbursts. That material is guided by the magnetic field around the star, to the axis of rotation of the magnetic field, which generally lines up with the axis of rotation of the star. Because of the angular momentum of the star, it should maintain that orientation and any new outbursts should go in the same direction as the previous burst.

Re:Gamma Rays

[Intron]

Note that the lobes appear to be tilted away from us by about 40 degrees or so. That's a good thing. When stars like Eta Carinae explode, they tend to shoot of beams of energy and matter that, at its distance of 7500 light years, could kill every living thing on Earth. But since it's pointed away from us, all we'll get is a spectacular light show.

Matter won't get here for quite a while, but the X-Rays, etc. will get here at the same time as the pretty light. For the energy to be enough to kill us at 7500 light years, and the inverse square law to be in effect, that means the energy density at the star's surface would be ... hmmm ... fairly large.

Re:Gamma Rays

[rubycodez]

but it is funny how astonomers say the explosion will "probably" go along the axis of rotation as the previous 19th century "belch" did (see wikipedia or nasa's web page). If "probably" is true, then things outside our atmosphere get fried, like sattelites, astrounauts on missions, etc. No big deal. But suppose that thing blows spherically, then the gamma dose will be many times greater and you'll be wanting a lead jock strap if you're male.

Re:Gamma Rays

[Control Group]

For the energy to be enough to kill us at 7500 light years, and the inverse square law to be in effect

That's kind of the point: the inverse square law isn't in effect, because the energy isn't radiated in all directions. This star is of a type that, when it goes nova, tends to emit its energy in a couple of highly directional beams.

Re:Gamma Rays

[flyingfsck]

Yup, be sure to build it right under your pyramid and keep wearing that armadillo hat and asbestos underwear... :)

Re:Gamma Rays

[secPM_MS]

There is good reason to believe that eta carniae will emit a powerfull gamma ray burst when it collapses. Since the axis of rotation is not pointed anywhere near us, we are at no risk from the gamma beam. It is also possible that it is massive enough to suffer a pair creation supernovae. A recent supernovae of this type in a presumed LBV (luminus blue variable) was ~ 100 X brighter than most core collapse supernovae. Regardless, it is to far away from us to create any type of radiation hazard or even cause problems with perturbing the day - night balance.

Re:Gamma Rays

[IWannaBeAnAC]

But the inverse square law still applies, because the beams still spread out with a diameter that is proportional to distance. This applies even to the best focused laser beams; although then the spreading of the beam is very small, it is not zero and the energy density still follows the inverse square law.

Re:Gamma Rays

[Anonymous Coward]

Eta Carinae shot first?

Re:Gamma Rays

[Anonymous Coward]

The inverse square law is always in effect. Lasers dissipate over distance just like sunlight - you can focus a laser down to a tight beam, but it still covers some number of microsteradians of spherical angle. So the area covered will increase as the square of the distance, so the energy per unit area goes as the inverse square.

Re:Gamma Rays

[The Bad Astronomer]

There are several forces that direct the outflow of an explosion. In this case, it's the rotation of the star coupled with its magnetic fields. When the core collapses, it forms a black hole. The inner parts of the star collapse down too, forming a flattened disk around the BH. The disk rotates quickly, and has ferocious magnetic fields. It's also incredibly hot. This forces material outward, along the poles of the disk. Two beams of energy and matter erupt out, forming what we call a gamma-ray burst. We're pretty sure this will be along the same axis as those two lobes which blew out in the 1800s. So they'll miss us. If the star explodes as a regular old supernova, it's too far away to do any damage; they have to be withing about 100 light years to harm us. I have references for all this, but I won't list them here. I'm writing a chapter in my next book about it... :-)

Re:Gamma Rays

[geekoid]

Scientist are always conservative when they talk publicly, it's the nature of the business
Now, get them to talk over a beer and pizza, it's a different matter.

Re:Gamma Rays

[QuoteMstr]

Holy cow, I didn't know you read Slashdot! I'm impressed, sir. :-)

Re:Gamma Rays

[The Bad Astronomer]

Oh, I prefer vodka or tequila, but the point is still true. :) It's not so much that we talk conservatively, as it is that people tend to tale whatever small thing you say and run with it. At least in my case that's true! I try to lay things out pretty clearly if I can. I think Eta has maybe a few hundred years left before it blows, tops, but others might give it longer. The point is, *we don't know*. But it'll be cool when it does explode. Woohoo!

Re:Gamma Rays

[Surt]

I wouldn't bother, as the sterilized soil and oceans means you're screwed in the long run.

Re:Gamma Rays

[monopole]

Damn, gotta build a lead Dyson sphere right now soon!!!

Re:Gamma Rays

[htaedtnelis]

Na, you just need to wear lead-lined pants until it's over. If you want to have kids that is.

Re:Gamma Rays

[fucksl4shd0t]

I'm no astrophysicist either, but I know that in an explosion, the center of mass is still in the same place it was before the explosion, and the center of mass of this thing is rotating around something (center of the galaxy?), so the entire explosion will continue to translate in that direction. At some point it will break up as gravity from other sources influences the particles, but the explosion itself will still be spherical, but continue in the direction it's going (assuming the center of the explosion is at the center of the star, otherwise you have to consider the masses of the chunks, but that should be irrelevant to what direction the particles travel immediately after the bang).

Re:Gamma Rays

[Jbcarpen]

He's a NERD! why wouldn't he?

Re:Gamma Rays

[fatphil]

Stars are spinning fluid systems. They have angular momentum, poles, and equators. I.e. radial symmetry. Anything that involves flinging part of their mass into space is also going to have radial symmetry, but not necessarily spherical symmetry. Beams from the poles, and disks from the equator are two typical shapes. If the beams spread out after ejection, then you can get dumbbells/hour-glasses.

Re:Gamma Rays

[fatphil]

Hoorah! This is so often overlooked.

All that changes with a supposed beam is a multiplicative constant.

One is led to enquire quite how wide the gamma ray beam would be at our distance. I.e. what is the multiplicative constant?

Re:Gamma Rays

[Z00L00K]

Well... If you want to keep safe you will probably need more than thin sheets of lead, you will probably need rather thick lead walls as well as being submerged in a deep lake or in the ocean. And don't forget to stack up with food for at least a year together with seeds to plant.

You will also need radiation detectors to make sure it's safe to come out.

A supernova is different from a nuke in the way that a nuke provides a short flash of radiation while a supernova's radiation is hard and stretches over days. This means that if we get a direct hit by the radiation from a supernova the current earth will end as we know it. It may be as bad as the end of the dinosaurs. Greenhouse Warming is nothing compared to this.

And anyway it's not even sure that a shelter will protect you against the radiation. It may only prolong the inevitable.

However - there is no need to panic - it doesn't help. Just realize that the world we live on is fragile and that we can't expect to have a resolution ready for everything. But this doesn't exclude the fact that we still should be trying to protect us. All those petty indifferences about religion are insignificant on the cosmic scale.

Re:Gamma Rays

[avtchillsboro]

Three quarters of the planet will be cooked--sunny side up!

Re:Gamma Rays

[rubycodez]

We're "pretty sure"


heheh, like I said. And an "average" supernova might be dangerous to 100 light years, but this particular star is abnormally huge. And let's not forget evidence of mass extinction and embedded meteorites in mammoth tusks from a supernova 250 light years away. Now suppose Eta Carinae does something unusually when it goes.....

Relative Time

[profplump]

Apparently da4 discovered some new non-relative timescale that's consistent throughout the universe without respect to position or velocity. That seems much more noteworthy than this supernova thing.

Re:Relative Time

[brunascle]

i was thinking the same thing, but actually kdawson added that little tidbit, not d4a :)

Re:Relative Time

[profplump]

My apologizes to d4a.

Re:Relative Time

[Tatarize]

Hm. If such a thing is constant then that star blew up years ago. It's seven thousand years away after all.

Re:Relative Time

[wsherman]

Apparently da4 discovered some new non-relative timescale that's consistent throughout the universe without respect to position or velocity.

It's an interesting point that an entity in a different frame of reference would not have quite the same ideas about space-time coordinates of this supernova happen but when you're reading an article written on earth for an entirely earth-based audience then it's pretty clear that the article is using space-time coordinates relative to the earth's frame of reference.

Also, aside from gravitational effects, how is space-time dependent on position?

Re:Relative Time

[IWannaBeAnAC]

I wouldn't give him much credit for the discovery. The timescale doesn't need to be consistent throughout the universe, just between Earth and Eta C. And that is no problem - it is precisely analogous to communication over a slow medium (say, a war zone where your only communication from the frontline is a runner that takes half an hour to travel the distance. If you get a note saying "help, we are going to be annihilated in 10 minutes", then you don't need to use general relativity to figure that that they died already 20 minutes ago). Unless Eta C is moving at a huge velocity relative to us (ie. something close to the speed of light), the relative motion is not important. Even if Eta C WAS moving at a huge velocity, then it would still be possible to calculate the timeline accurately, you just need to be more careful about it - and it will be a slightly different timeline for a different observer.

Re:Relative Time

[Anonymous Coward]

... But that's not the same as Eta Car's frame. An expression like "it happened 7,500 years ago there" is very poorly defined. We travel on a number of acceleration vectors, our own spin, orbit around the sun, orbit around the galactic core, while Eta Car differs on all of those.

Even in special relativity those effects are important

http://en.wikipedia.org/wiki/Relativity_of_simulta neity

Re:Relative Time

[profplump]

Both your battlefield parties are in more or less the same frame of reference as they are only separated by a few miles; their limitation in communication speed is artificial and *not* related to some fundamental physical limit like the local speed of light in a vacuum. That's not the case with light coming through space from a very distant object. The timescale is different because of the distance itself, not just our relative speed.

Re:Relative Time

[profplump]

If Eta Car is in our frame of reference then the explosion happens more or less when we see it, by definition. If Eta Car is not in our frame of reference then the comparison is not so simple.

Re:Relative Time

[wsherman]

But that's not the same as Eta Car's frame.

That's definitely an interesting point. Without knowing Eta Carinae's relative velocity and acceleration, it's possible that from Eta Carinae's perspective (frame of reference), the earth will observe the supernova 6,000 years after it happens but from the earth's perspective (frame of reference), the earth will observe the supernova 7,000 years after it happens.

I suppose that from a scientific perspective, there is a certain appeal to choosing a frame of reference relative to the event (Eta Carinae) rather than the observer (earth). On the other hand, I still think that, given the intended audience of the article (people on earth), the times are clearly being expressed relative to the earth reference frame.

An expression like "it happened 7,500 years ago there" is very poorly defined. We travel on a number of acceleration vectors, our own spin, orbit around the sun, orbit around the galactic core,...

And yet, somehow "we" (people on earth) manage to define the passage of time down to a very very small fraction of a second. While it is interesting to consider other perspectives, the summary in question was clearly referring to the frame of reference used to define the standard passage of time on earth (accelerations and all).

Re:Relative Time

[IWannaBeAnAC]

I think you are wrong here; you are thinking of time dilation effects, but unless the objects are moving very quickly with respect to each other then they are more or less in the same inertial frame of reference and there is no time dilation. The distance per se has nothing to do with it. Of course, if Eta C is moving at close to the speed of light relative to us, then it is a different story.

Re:Relative Time

[wsherman]

If Eta Car is in our frame of reference then the explosion happens more or less when we see it, by definition.

Well, we would still take into account the speed of light and the distance to Eta Car (relative to our reference frame). If Eta Car is 7,000 light years away (relative to our reference frame) and we observe the explosion now then, in our reference frame, the explosion happened 7,000 years ago.

There are standard definitions of the passage of time on earth so the time is not a problem, specifically. The tricky bit is that our notions of the distance to Eta Car may fluctuate a bit as we accelerate toward and away from Eta Car on our orbit around the sun. With a bit of care, though, we could probably average these fluctuations out - although that may not be strictly kosher from a relativistic point of view.

Re:Relative Time

[Torvaun]

Lightyears, not years. Years are just time, and it's quite a bit more than 7,000 of those away if you decide to jog it instead.

Re:Relative Time

[Anonymous Coward]

Dialation has to do with my timescale compared to that of others that are spacially local to me. I'm not talking about time being "slower" or "faster"; that effect would change the frequency of the observed waves, regardless of the distance between the objects.

I'm saying that moment A at Eta C -- the moment of the supernova -- doesn't occur at the same time at all points in space. Given our knowledge of the speed of light we can calculate that an observer local to Eta C would have seen the supernova long ago, but that's not the same as the light itself being very old.

Re:Relative Time

[Tatarize]

Well, relativistically speaking, there's no difference between seven thousand years and seven thousand lightyears when talking about distance away in spacetime. If I were traveling at the speed of light, I would be there in no time (literally no time), though when you arrived it would be 7000 years later.

I stand by my comment. Eta Carinae is seven thousand years away.

Ummm...

[TheSHAD0W]

All I can say is, if you see Al Gore, Michael Moore and Noam Chomsky wearing robes and riding camels... run like hell.

Re:Ummm...

[rossz]

That was funny. If I had any moderation points left I would have given you one.

Re:Ummm...

[EricTheGreen]

Shouldn't we do that anyway, supernova or not?

When will it explode?

[dfn5]

they really mean it probably exploded 6,500 to 7,500 years ago and we're awaiting the news.

When?
Now.
Now?
Now.
I can't
Why?
We missed it.
When?
Just now.
When will then be now?
Soon!

Re:When will it explode?

[flyingfsck]

You missed 'now now' and 'now then', but you already scored 10 bonus points for the use of 'just now'. :)

Re:When will it explode?

[fucksl4shd0t]

Ah hell, give the guy full credit just so people who have the vaguest slightest notion won't get a curve. Everytime I try that joke people just stare at me blankly or try to say I'm doing who's on first.

Define "soon"

[ducomputergeek]

As in we'll get to see the bang in a year? A decade? A Century?

A hundred years is a blink of the eye to the universe.

Re:Define "soon"

[Goaway]

A hundred years is a blink of the eye to the universe.

Yes, you're getting it now.

Re:Define "soon"

[Sponge Bath]

...blink of the eye to the universe.

And humans are... eye crust?
Bummer.

Re:Define "soon"

[Spudtrooper]

Now you tell me. I've been sitting outside with my shoebox pinhole camera for like 2 hours!

Re:Define "soon"

[Brad1138]

How to correlate "soon" in respect to the universe with a Slashdotter.....? Ah...

How soon will you get laid? Should be similar.

Re:Define "soon"

[Anonymous Coward]

That reminds me, I had a dream last night that I spoke to God.

I said, "God, a billion years is like a second to you, huh?"

He replied, "Yes."

I continued, "And a billion dollars is like a penny to you."

"Again, yes."

"So, can I have a penny?"

"Of course you can...in a second."

Neutron emissions

[Weaselmancer]

IIRC, one of the ways that life could be wiped out on this planet is if a nearby star goes supernova and bakes us with the neutron output.

Obviously, this isn't the case with this star or people would be emptying their IRAs and going to Rio - but I have to wonder. Will there be any impact here on Earth from the explosion?

Re:Neutron emissions

[Mattintosh]

Will there be any impact here on Earth from the explosion?

Doubtful. Stars contain little or no solid matter, and the likelihood of a cosmic cueball (planet chunks, anyone? let's hope it's not kryptonite, I'd rather "kryp" tomorrow) coming our way is roughly zero.

Perhaps you meant "effect" rather than "impact". In that case, yes. We will recieve a tiny slice of its output of visible-spectrum radiation, an infintesimally small amount of "harmful" radiation, and some good scientific fodder. Oh, and if Hubble's still up, some awesome desktop pictures.

Re:Neutron emissions

[Kagura]

I don't think it's the neutron output, rather it's the energetic gamma rays that do you in. Maybe your shield's flux capacitor needs to have its polarity reversed.

Re:Neutron emissions

[WrongMonkey]

Note that the lobes appear to be tilted away from us by about 40 degrees or so. That's a good thing. When stars like Eta Carinae explode, they tend to shoot of beams of energy and matter that, at its distance of 7500 light years, could kill every living thing on Earth. But since it's pointed away from us, all we'll get is a spectacular light show. It could potentially wipe out life on Earth, but its pointed in the wrong direction...hopefully.

Re:Neutron emissions

[Torvaun]

Impact in that context did not mean collision. Nice explanation, though.

Re:Neutron emissions

[wildsurf]

It could potentially wipe out life on Earth, but its pointed in the wrong direction...hopefully.

Ahem, I would humbly opine that it is pointed in the RIGHT direction... :)

Re:Neutron emissions

[nih]

It could potentially wipe out life on Earth, but its pointed in the wrong direction
great, looks like i have to go to work on Monday after all :(

Re:Neutron emissions

[Mattintosh]

Unfortunately, Tom Brokaw has convinced a great many people that something can "impact" you and yet not physically hit you. Don't believe his hype.

Something can impact you only if it hits you. Something can have an impact on you (note the posessive form) without hitting you, in which case it affects you (non-posessive form, equivalent meaning). And it gets worse day by day. The nearly braindead local news feebs latched onto the phrase and things lately have become "impactable" (vulnerable to an effect), or worse, "impactful" (full of impact? I'm not sure...). In the past tense, things have been "impacted"... like a wisdom tooth, I guess. No? You mean they were affected? Strange... I could've sworn someone said "impacted".

I blame Tom Brokaw for the mispronunciation of Missouri, too. It's not Misour-ee, it's Misour-ih (or if you're lazy, Misour-uh). Misery loves company, and Tom Brokaw says I live there.

Language changes and all, but sometimes it's a bit ridiculous. I still chuckle about "impactful". Yikes.

If we detected it today. . .

[Platupous]

What would be the repercussions for earth? Since the lobes are pointed away, we don't seem to be in danger, but surely there would be some effects, what exactly would they be? (Besides "Good show"!)

What if the lobes were pointed this way, what exactly could we expect? (Besides "Bad!")

Re:If we detected it today. . .

[moore.dustin]

How thinned out would the lobes be? Probably nothing major by the time it got here? Assuming it spreads out to infinity in all directions. I would think that our magnetic field could handle it by the time it got here. Just a guess of course, perhaps someone can chime in with some knowledge.

Re:If we detected it today. . .

[Anonymous Coward]

what exactly could we expect?

Half the face of the earth being wiped off the face of the earth, followed by the survivors banding together and developing spaceships, stations, and moon bases for the purpose of defending the solar system and Earth from the debris that would arrive centuries later.

Ultimately, the plan will be successful thanks to a couple of genius school kids and a giant robot.

Re:If we detected it today. . .

[brunascle]

my guess is, if you need a telescope in space to see it, you'll be fine.

Re:If we detected it today. . .

[SpryGuy]

A few nights of having a star in the night sky that is brighter than the moon, perhaps?

And lets not forget all the religious fanatics taking it as a sign, and panicking, and causing social unrest or upheaval around the globe.

Re:If we detected it today. . .

[pauljuno]

Did you see the series finale of the Sopranos? Yeah, kind of like that.

Re:If we detected it today. . .

[0p7imu5_P2im3]

Didn't that happen once in the dark ages: a major supernova had people thinking Christ had returned or Satan was reigning, or something?

Re:If we detected it today. . .

[Anonymous Coward]

I think the main worry is the gamma rays creating NOx and stripping away our ozone layer, leaving us no protection from UV radiation.

Re:If we detected it today. . .

[AxemRed]

I have read about this star before as well as other supernovas or stars that are likely to turn into supernovas soon. From what I remember, a supernova poses no threat unless the poles of the star are pointed towards us. It just makes a really bright "star" in the sky for a short amount of time. If one of the poles of the star is pointed at us, we get hit by a burst of gamma rays. The gamma rays destroy the ozone layer, and then the sun's UV kills large amounts of life on Earth.

Re:If we detected it today. . .

[hyperstation]

you're thinking of 1054, and yes, it would have been a seriously badass event to see. http://en.wikipedia.org/wiki/SN_1054

Re:If we detected it today. . .

[Anonymous Coward]

This just in...

NASA Bans All Mix Tapes Containing 'Journey' Songs
No Reason Given By Officials

Re:If we detected it today. . .

[Chris Burke]

You may be thinking of SN 1006, the brightest supernova in recorded history. It was significantly brighter than Venus, though not as bright as the moon. It was bright enough to be easily seen during the day, and was bright enough to read by at night. This event was documented in Chinese, Egyptian, Middle Eastern, Swiss, and even North Americans records, as one would expect of something so amazing. Yet it is conspicuously absent from any other European writings, and the common story (i.e. i can't coroborate at all, may be apocryphal) is that the Church and their "perfect unchanging universe" doctrine made it heresy to even acknowledge that the thing was even there.

Or, maybe you're thinking of SN 1054, which according to Wikipedia may have been described by Irish monastic monks, but was later corrupted into a story of the Antichrist.

Re:If we detected it today. . .

[Anonymous Coward]

causing social unrest or upheaval around the globe.

Just like they do when there's a comet - because as you know, our civilizaton collapses every time a comet flies by.

Oh wait, it doesn't. So I guess you're wrong.

Re:If we detected it today. . .

[Attila]

And lets not forget all the religious fanatics [...] panicking, and causing social unrest or upheaval around the globe What? Just for a change, you mean?

Re:If we detected it today. . .

[Glowing Fish]

Where was it positioned in the sky? It might have been below the southern horizon in Europe. China, North America, Egypt and the Middle East are all south of Europe. Beijing (in the far North of China) is south of Rome, or Madrid. So maybe that is why no one in Europe knew about it.

Re:If we detected it today. . .

[Chris Burke]

It would have been low in the southern sky, but it was visible from Switzerland for certain because they have recorded observations, so it should have been visible from most of Europe. Certainly from the Vatican. Which, if the story is true that the lack of recorded observations is due to Church doctrine, would have made for some awkward services with people piously refraining from looking to the south.

Re:If we detected it today. . .

[Anonymous Coward]

What would be the repercussions for earth?

We are all going to die.

Re:If we detected it today. . .

[Bramantip]

Yet it is conspicuously absent from any other European writings, and the common story (i.e. i can't coroborate at all, may be apocryphal) is that the Church and their "perfect unchanging universe" doctrine made it heresy to even acknowledge that the thing was even there.

What a bunch of nonsense.

SN 1006 was observed by Hepidannus, who happened to be a monk of St. Gaul. So not only was he Catholic, but a member of a religious order (that is, the clergy). He died in A.D. 1088 Quotation:

Nova stella apparuit insolitae magnitudinis, aspectu fulgurans et oculos verberans non sine terrore. Quae mirum in modum aliquando contractior, aliquando diffusior, etiam extinguebatur interdum. Visa est autem per tres menses in intimis finibus Austri, ultra omnia signa quae videntur in caelo. (Hepidanni Annales breves, in Duchesne, Historiae Francorum Scriptores, t. III 1641, p477.

Also a reminder that Copernicus himself was a Franciscan monk and priest.... and that the author of the 'Big Bang' theory was himself a Catholic priest.

Perhaps the lack of European observations might simply be because the black death had taken much of the European interests away from the sky and to things more pressing. In any case your 'theory' about the Church is really just nonsensical.

Re:If we detected it today. . .

[Bramantip]

Small error - I should not have said that he 'observed it' but rather 'recorded it'. He was writing a chronicle, not his own observations. In any case that only proves that someone did indeed observe it and wrote it down before he compiled his chronicle.

JJ +

Re:If we detected it today. . .

[mapkinase]

Sheesh! Thank you, /., for not moderating the parent down. Perfectly informative and on subject reply was completely overlooked and ignored by moderators, because it does not fit into "religion is evil" concept reigning at /.

Yeah, yeah, mod me down for my trolling, flaimbaiting and off topic remarks.

Re:If we detected it today. . .

[Chris Burke]

St. Gall being in Switzerland, yes, that makes sense. It also makes sense that a monk would be more interested in intellectual pursuits than most. I don't see how the rest of Europe could have failed to record it due to lack of interest, though. This wasn't just astronomy, it was a suddenly appearing day-time-visible star, and surely had to be taken as a portent of some kind.

It's not my theory, it's a theory I've heard from several other people and which, as I noted, could easily be aprocryphal.

What's the relevence of Copernicus and Lemaitre when they came over 4 and 9 centuries later, by the way? If you thought the underlying thesis of my post was "the Catholic church has hated astronomy at all points in history with no change" then you were wrong.

Re:If we detected it today. . .

[Bramantip]

I don't see how the rest of Europe could have failed to record it due to lack of interest, though. This wasn't just astronomy, it was a suddenly appearing day-time-visible star, and surely had to be taken as a portent of some kind.

True enough. It is curious that there are few records of this 'new star' in European writings - but then again, how many chronicles do we have of the 11th century? And how many of these chronicles have actually been read? It is perhaps a little over-zealous to conclude that people were to be condemned for astronomy simply from a lack of witnesses to one event.

For what concerns LeMaitre and Copernicus, these were just examples. One could cite works from St. Augustine (died 430), Thomas Aquinas (13th century), Albert the Great's commentary on de Caelo et Mundo - there is an enormous amount of work on astronomy from the beginnings of our era throughout the Middle Ages. Astronomy was a chief subject of study throughout the middle ages, forming part of the Quadrivium. Copernicus didn't just invent his theories of a sun-centered system and changes in the heavens, he inherited them and simply had the observation data to prove its correspondance.

I merely cited these two examples as simple counterexamples to the claim that the Church hated astronomy. The opposite is rather the case - in fact, since the Christians pray to 'Our Father who art in heaven', the heavens were of profound interest to them. Thus I would say that the story you heard was more than just apocryphal - it is just plain wrong.

But of course that wasn't the object of your post. It is curious though why there are not so many witnesses in Europe - but then again, how many do we have from China? I could only find one through Google, so perhaps the Chinese also have an aversion to astronomy....

Re:If we detected it today. . .

[SpryGuy]

That's a fair cop.

anywhere from today while i am typing to 10M yrs

[Anonymous Coward]

Anyway since many observatories have to spend time looking at other crap .. I think we should have a telecope permanently aimed at Eta Carinae taking pictures in succesion (aka video).

Let's see .. we need about initially $40K ($25K for a phat telescope +computer, rest for the housing of it etc.)

Hmm actually make that ($40K x 4 = $160k) because I think we'll need eastern hemisphere coverage and there should be two sites in each hemisphere to reduce the chance of being screwed over by cloud cover.

Safety first - Keep those lobes pointed down

[Anonymous Coward]

From the article:

> Note that the lobes appear to be tilted away from us by about 40 degrees or so. That's a good thing. When stars like Eta Carinae explode, they tend to shoot of beams of energy and matter that, at its distance of 7500 light years, could kill every living thing on Earth. But since it's pointed away from us, all we'll get is a spectacular light show. If you're keeping score at home, gamma-ray burst aimed at you = bad, pretty supernova with no accompanying high energy radiation = good.

Who new the universe was such a dangerous place? Time to move to a safer neighborhood.

Preview

[tygt]

Maybe we should be keeping our eyes open for a blast of tachyons ahead of the light show ;)

I hope no one died.

[0p7imu5_P2im3]

I just hope that any local civilizations had advanced far enough to escape that horrible fate.

At the rate we're going, what with news of Congress living up to their name (opposite of progress) with regard to exploration the exploration of Mars, we won't escape the fate of our solar system.

Re:I hope no one died.

[spun]

Eta Carinae is so large, it is almost too big to be a star. It has been blowing itself apart every now and then since it was born. I find it unlikely in the extreme that any life could have developed nearby. I doubt the system even has planets.

Re:I hope no one died.

[The Real Nem]

I'm not sure how fast this "force" thing moves, but no one seems to have felt a great disturbance in it yet...

Re:I hope no one died.

[toganet]

I just hope that any local civilizations had advanced far enough

As an antiteleologist, I take offense at this statement.

Re:I hope no one died.

[Chris Burke]

I'm not sure, but I think that according to Star Control II that Eta Carinae did have planets, and at least some of them hosted alien life forms.

Re:I hope no one died.

[iHasaFlavour]

Gas giants are a possibility, since they can formn very rapidly

See the following

www.gps.caltech.edu/~gab/ge128/lectures/boss_jupit er.pdf

As to lifespan of these gas giants, I have no idea.

Re:I hope no one died.

[lawpoop]

Unless that type of life is unlike what we know as life, and arose in the energy the star was throwing off, perhaps feeding off of it, like green plants feed off energy our star throws off.

Re:I hope no one died.

[Anonymous Coward]

Don't you know that the blasts of gas are the last ditch attempt of an alien civilization to jet their entire solar system away from some EVEN WORSE catastrophe?

Re:I hope no one died.

[Reality Master 101]

I just hope that any local civilizations had advanced far enough to escape that horrible fate.

Don't worry, the probability of other intelligent life in this galaxy is pretty much zero.

At the rate we're going, what with news of Congress living up to their name (opposite of progress) with regard to exploration the exploration of Mars, we won't escape the fate of our solar system.

Several things to say about this:

1) Colonization of other planets in this solar system will NEVER happen. And I mean never. Because a) Environmentalist scientists will convince government to never allow the unique environments to be spoiled, b) once people get over their romantic notions of living on other planets, they will realize they are cold, ugly, radiation-infested, inhospitable rocks, and very few people will want to live there. Proof? How many people want to live in Antarctica? And Antarctica is an order of magnitude more hospitable.

2) The future of space colonies is very large cities floating in space. You can get earth-like gravity (via spinning0, earth-like green environments, and all the romanticism of "living in space". There is still the radiation problem, though.

3) If we do have space colonies, Congress *certainly* won't be the one to build them. It will be private people wanting to make a buck on tourism, and later mining, that will establish the permanent colonies.

4) People on Mars is a total waste of money. If we were dedicated (and killed the space shuttle), we could send 1,000 probes for what we waste on sending humans, and get far more science.

(I realize this post is a little aggressive on opinions, but I'm in a naivete-busting mood today. :D)

Re:I hope no one died.

[hyperstation]

goddammit, you just like, blew my mind...

Re:I hope no one died.

[WhiteWolf666]

Local civilizations?

Err... Buddy?

That's us.

In the cosmic scheme of things, 7500 ly is not far. Think of it this way; if we're wrong, and something bizarre happened, and one of the "gamma ray bursts" is aimed at us rather than another direction, by the time we visually see the hypernova we'll be dying and/or dead.

As it is, assuming that the gamma ray blasts follow its rotational axis, we'll be fine on the planet, but anything we've put into space has a good chance at being toast.

The unfortunate part is that the killer won't be a superheated cloud of gas travelling at .1 c . It's going to be a burst of gamma radiation, so by the time we sense it, we're dead.

Re:I hope no one died.

[geekoid]

don't open your mind so much that your brains fall out.

Re:I hope no one died.

[halcyon1234]

Yes, but the Star Control II Eta Carinae isn't the same star:

Defined long ago by Chenjesu stargazers, the constellations are now accepted by all Alliance races as the standard. Due to the great difficulty in pronouncing the Chenjesu language, each race has translated the names into their own tongue. When it came time for Earth to adopt this system, the United Nations decided to use traditional astrological designations, assigned at random. This has caused some confusion, but it is considered preferable to the suggested alternative: using the names of past politicians.

- The Star Control II Map

Map can be viewed here

Re:I hope no one died.

[lawpoop]

Hey, energy beings don't have brains ;)

Re:I hope no one died.

[Chris Burke]

Heh. I also like the part about "The positions are based on HyperSpace coordinates, which may be unsettling to some students of TrueSpace astronomy". All in all a humorous way to account for taking our section of the galaxy and making it 2D, and a joke I didn't appreciate having only played the Ur-Quan Masters OSS version of SC2.

Re:I hope no one died.

[spun]

Come on, we have one data point to go on vis a vis life in the universe. He's right, life could be anything. But at the same time, until we have more data points to go on, or at least some way to test them, speculations such as that are kind of pointless. We should focus on looking for the kind of life we know can exist in our universe. And we ain't finding it around Eta Carinae, that's for sure. Have you seen those animations of that thing blowing up? And supposedly it does that again and again because it is so big and hot that the internal radiation pressure is greater than the force of gravity holding the thing together. I doubt even lawpoop's energy beings could live in a place like that. But it's all just speculation, not even an educated guess. Even if we figure out some kind of TOE, there will still be so much we don't know about the specific emergent properties of our universe. Until we get out there and look.

Re:I hope no one died.

[Anonymous Coward]

Don't worry, the probability of other intelligent life in this galaxy is pretty much zero.

It seems to me that the fact that extraterrestrial civilizations haven't contacted us is the strongest evidence in favor of their existence.

Re:I hope no one died.

[rholland356]

At the rate we're going, what with news of Congress living up to their name (opposite of progress) with regard to exploration the exploration of Mars, we won't escape the fate of our solar system.

Oh, you'll have to explore a lot further away than Mars to escape the fate of our solar system. Trouble is, after Mars, there is nothing worth reaching for unless it is beyond our solar system. So, sinking effort into Mars and the Moon is dead-end thinking.

And investing--now--in habitats and space trucks is a waste of effort and resource. Skip the transport of wetware completely and focus effort on development of robotics, nanotech, AI and propulsion. Master every corner of this solar system, without any human presence at all. Solve the tech problems here on earth, then export solutions--not problems--to other regions.

And while you wait--free rides in the vomit comet for everyone!

Re:I hope no one died.

[Torvaun]

Type of life unlike any we already know. Feeds off of energy. If it kills people through total blood clotting, and later mutates to eat polymers, then Crichton will have to rename his book to the Eta Carinae Strain.

tinfoil will save ya

[wwmedia]

time to go up the attic and find my trusted tinfoil hat

Re:anywhere from today while i am typing to 10M yr

[stoolpigeon]

And what do we do if the star just vanishes from view in an instant?

Re:anywhere from today while i am typing to 10M yr

[Joseph_Daniel_Zukige]

Anyway since many observatories have to spend time looking at other crap .. I think we should have a telecope permanently aimed at Eta Carinae taking pictures in succesion (aka video). Let's see .. we need about initially $40K ($25K for a phat telescope +computer, rest for the housing of it etc.) Hmm actually make that ($40K x 4 = $160k) because I think we'll need eastern hemisphere coverage and there should be two sites in each hemisphere to reduce the chance of being screwed over by cloud cover.

If you're thinking to try to get a bunch of astronomy geeks to dedicate the lens, camera, and computers to this project, why post AC?

A little late??

[Berserker76]

..so Slashdot is reporting as news an event that happened an estimated 6,500 to 7,500 years ago. Would we file this under current??

Thanks Slashdot!

Re:A little late??

[Anonymous Coward]

Well, it's not likely to be a dupe...

Re:How fast are the gamma rays moving?

[spun]

Let me introduce you to a thing called the Internet. You can use it to look up facts and dispel ignorance. Well, I can use it that way, anyhow. Evidently you can't. Here you go: http://en.wikipedia.org/wiki/Gamma_radiation

In short, gamma radiation is light. Just very, very high frequency light.

It's all Carter's fault

[FrostedWheat]

"You know, you blow up one sun and suddenly everyone expects you to walk on water."

Re:i've been

[MobileTatsu-NJG]

"...rubbing my dick on pictures of bob saget, and i'm ready to explode real soon now, too." ... and the name of this show, The Aristocrats!

Real Soon Now

[Jugalator]

Keep in mind that on a cosmolical scale, that could be within 10,000 years or so, a few nuclear wars and greenhouse disasters later. ;-)

The problem with suprnova's...

[cadu]

...is that they disappear misteriously after a brief period.

Re:The problem with suprnova's...

[HeadlessNotAHorseman]

I wish more women were like that!

Guuys.. anyoone?!

[nlitement]

Does this mean that we're gonna die soon?!?! :'(

Re:Guuys.. anyoone?!

[geekoid]

only the southern hemisphere ;)

Re:Guuys.. anyoone?!

[tizan]

Yup...you are going to die. That is a certainty...

May be tomorrow may be in 60 years...may be because of a supernova or old age

But on a lifetime of a star its soon.

And if you man humanity...we are gonners by either our stupidity or by the planet or evolution getting rid of us...100000 years ago we were bumbling idiots...and in 100000 years we are extinct or evolved into something less idiotic...so yes we are gone.

How to figure out which star you are looking at?

[Bender Unit 22]

I know this is offtopic but hoping for some answer. How can I figure out which star I am looking at.
If I am herelooking South(a bit east) and can see a very bright star in the early evening way before all the others?

Are there a online version of a starmap where you can type in your location, date and the direction or something?

Re:i've been

[R00BYtheN00BY]

I agree with the OP.

And the scream...

[Evil Attraction]

...of trillions of aliens can be heard approx. 7500 lightyears away. In all directions. Aaaaw.

--
So be it!

Seeing Eta Carinae for yourself

[spaceyhackerlady]

The southern hemisphere sky has lots of goodies that us northern types don't get to see, and the Eta Carinae region is one of them. The nebula is slightly larger than the Orion Nebula as seen from Earth, but slightly dimmer. To me it looks like a flower blooming in space. It is accompanied by zillions of other nebulae and star clusters.

The Milky Way through Centaurus and Carina is why astronomers often go to places like Australia for their vacations. I've taken a telescope to Costa Rica several times myself, and while the view isn't as good as it is in Australia, it's a lot less travel. The only thing we really miss out on from Costa Rica are the Magellanic Clouds, which look far better from New South Wales than they do from Guanacaste. The vague smudges down at the Tico horizon are detached pieces of the Milky Way in the Aussie country sky.

My first view of the Eta Carinae region was with binoculars from St. Kilda Beach in Melbourne. It's not something one quickly forgets.

...laura

MOD PARENT UP - Author of TFA, smart guy

[halcyon1234]

I don't normally MPU, but I'm out of mod points, and the above post is kinda buried-- and kinda informative.

Re:How to figure out which star you are looking at

[tqft]

http://heavens-above.com/

or stellarium if you want an excellent downloadable app

Re:anywhere from today while i am typing to 10M yr

[gardyloo]

I think we should have a telecope permanently aimed at Eta Carinae taking pictures in succesion (aka video). No way! We'll get arrested for felony wiretapping if we do that.

Re:How to figure out which star you are looking at

[Platupous]

Try: http://www.fourmilab.ch/yoursky/

Re:How to figure out which star you are looking at

[V1b3s]

These days, the brightest thing in the evening sky to the south-south-east is the planet Jupiter (get a pair of binoculars, at least 50mm, and you'll be able to see the disc and tell that it's not a star... maybe even make out some of the four Gallilean moons).

It could be one of a couple of other stars, but I'd put money on your bright "star" being Jupiter.

Hubble image of nebula

[novus ordo]

I was looking for a nice desktop image and happened to come upon this panorama of Carina Nebula. This supernova is clearly visible(not fake colored x-ray) in the image, it is about 1/4 from the left side and in the middle of the picture just left of the big blob of dust. Curiously it has some sort of crosshairs on it, probably an optical illusion but nontheless interesting.

Re:Hubble image of nebula

[NormalVisual]

Eta Carinae's not a supernova yet. :-) The crosshairs you're seeing are called "diffraction spikes", and are caused by the diffraction of light around the secondary mirror supports in the telescope. Reflecting scopes with two or four vanes supporting the secondary mirror will result in 4 spikes, and three-vaned scopes (like mine) will give you six spikes. Refractors, Schmidt-Cassegrains, and other scopes without support vanes aren't prone to the issue.

Re:How to figure out which star you are looking at

[majiCk]

Check out Stellarium, a cross-platform OpenGL application that takes your coordinates and gives you a realistic 3D night sky, with optional star names, constellation names, constellations, and all kinds of other nifty features. It's perfect for a night of stargazing.

In that case

[PingPongBoy]

probably exploded

Ergo, nothing to see here, please move along

Bipolar Symmetric Objects

[pln2bz]

There's something that doesn't quite follow with this article. The article states that we are only in danger when the bipolar configuration faces us. However, when the bipolar morphology faces us, it will look just like a sphere. The other lobe will be obstructed by the one closest to us. Somebody please correct me if I'm wrong, but how often do we see spherical objects in space as being identified as a bipolar configuration pointing at us?

Couldn't a person make a pretty convincing argument that the bipolar configuration is in fact the primary configuration of all such objects, and that anything that looks like a sphere to us is in fact just the bipolar configuration pointing at us?

Re:Bipolar Symmetric Objects

[Anonymous Coward]

Um...no. Assume a random angular distribution and the integrated probability of something pointing sufficiently toward us to simply look like a sphere is vanishingly small. Sure, there are things in the sky that must be pointing at us in this way, but making the argument that "anything that looks like a sphere to us is in fact just a bipolar configuration pointing at us" is tantamount to declaring that the Earth is the center of the universe, since it depends on every object aligning itself with Mecca.

Re:Bipolar Symmetric Objects

[The Bad Astronomer]

That's an astute question. Perfect spheres are hard to come by in astronomy, though they're out there (Abell 39 is probably the best example: http://antwrp.gsfc.nasa.gov/apod/image/0101/abell3 9_wiyn_big.jpg). The famous Ring Nebula (http://antwrp.gsfc.nasa.gov/apod/ap060625.html) is an object that people thought was a ring, but it turns out to be barrel-shaped and pointed at us. That happened a lot. Bipolar objects are very common, since lots of objects either spin or have disks, which shapes the outflow into two lobes of some kind.

"Soon"

[Alsee]

Just to clarify for everyone, this supernova is "soon" as in (quoting Dubya Bush) "I'd like to get our troops out as soon as possible. But the definition of 'as soon as possible' is depending upon victory in Iraq".

-

Re:"Soon"

[Anonymous Coward]

doesn't this sentence make any sense to you? are you another moronic college graduate who should have never passed 10th grade english?
 
he's saying that the troops should be pulled asap but he acknowledges that it's not possible to leave while there is turmoil.
 
or are you one of those fucking idiots who can't see the harm in leaving the country in a power vacuum? you know, that's what happened in a little place called afghanistan. or do you really want our troops facing a well organized, trained and established islamic front? do you really want militant muslims in control of a country that can make or break the economies of most of the first world nations? you know, things aren't going so well for the saudis either, if you'd care to pay attention.
 
i know all of you fucktards like to think that bush is going to be the downfall of the us, and he certainly has done his part but it's very clear that you guys are trying to help to rush it along. this is a critical time and the next century of global power is going to be won or lost in the next decade. this is no time to fuck around.

Re:"Soon"

[Alsee]

Hi there Mr. Anonymous Coward, did you eat paint chips as a child? God you're brain damaged. I fully understood what Bush said, and I can't imagine what sort of brain damage you have that made you think I didn't. But gee, thanks for "explaining" what Bush meant for me, I feel so much better having a random anonymous retard confirm that Bush did in fact mean exactly what I already understood him as meaning.

I'll try to put this into small direct words for you. I said both the nova and "Bush's victory in Iraq" will happen in the same "soon", as in some random year probably before 3000.

he's saying that the troops should be pulled asap but he acknowledges that it's not possible to leave while there is turmoil.

Yup. If we stay, the turmoil will end some time "soon".
If we pull out, the turmoil will also end some time "soon".

or are you one of those fucking idiots who can't see the harm in leaving the country in a power vacuum?

I guess you're one of those idiots that can't see that the damage is done. Bush drove this car right off a cliff. Turning the steering wheel now isn't going to fix anything, and keeping the steering wheel "Stay The Course" straight ahead sure as fuck isn't going to fix anything. Bush has this car airborn and going 200 MPH - a vertical 200 MPH downwards. Pulling the troops out will make things worse. Leave the troops there, and they will keep dying and keep dying, and their very presence in Iraq is going to make things worse as a despised PERMANENT OCCUPYING INVADER FORCE.

But thanks for your paint-chip-eating insight. Have a nice day.

-

Re:"Soon"

[Anonymous Coward]

No, I drank the tangy liquid found in thermometers.

Verb Conjugation and Time Travel

[Stormy Dragon]

>Of course when astronomers say it's "about to explode," they really mean it probably exploded 6,500 to 7,500 years ago >and we're awaiting the news So it's "about to will have had been exploded"?

Where's the Kaboom?

[Anonymous Coward]

There was supposed to be an earth shattering Kaboom!

My Illudium Q-36 Explosive Space Modulator! That creature has stolen the space modulator!

Re:How to figure out which star you are looking at

[Bender Unit 22]

Thanks, we have a pair of binoculars, I'll see if they are any good. :)

Re:How to figure out which star you are looking at

[Bender Unit 22]

Excellent, there's a Mac version too, I'll check it out. thanks.

Eta C is not 7500 light years away for me

[benhocking]

I'm traveling close to the speed of light, you insensitive clod! In fact, I'm traveling so fast, that the Lorentz contraction has resulted in Eta C being only a light day away. Ergo, it is very unlikely that in my inertial frame of reference that it has already gone supernova! That was the point that the GP was trying to make. Also, it's special relativity that tells us how the passage of time depends on your velocity in space, whereas general relativity also tells us how it is affected by acceleration and gravitational fields.

Re:Eta C is not 7500 light years away for me

[IWannaBeAnAC]

No, even in that case Eta C has already gone supernova. It might only take you one day to get to Eta C in your frame of reference, but in the frame of reference of Eta C (or the frame of reference of the Earth, for that matter) it will take very close to 7,500 years. Since it already went nova at least 6,500 years ago, you will be at least 14,000 years too late if you wanted to see it up close.

Re:Eta C is not 7500 light years away for me

[Surt]

* Interstellar travelers who want to see SuperNovae up close are advised to bring Sunglasses and Sunscreen.

Re:Eta C is not 7500 light years away for me

[VendettaMF]

And a surfboard with a portable black hole heatsink.

Re:How to figure out which star you are looking at

[Bender Unit 22]

Cool, by looking at the search result, combined with another answer I got, I think it must actually be Jupiter. So it's a planet. :)

Thanks.

What makes you tick, pln2bz?

[spun]

You know, I've read your Electric Universe arguments here many times before, and I'm curious. What's your background? What drew you to the EU theory?

I'll tell you the problem I have with the theory, it's the whole, "There is no fusion in stars, it's all electric!" thing. Certainly we don't know everything there is to know about plasma, and certainly the mainstream theories do not have everything nailed down, but come on! The science behind star fusion is so interwoven with all of modern knowledge and technology that if something as major as EU were true, almost everything else we know would have to be false, and all our technology would be very different.

The thing is, the Electric Universe folks make an extraordinary claim. Extraordinary claims require extraordinary proof. If anyone in the EU community had that proof, they would be world famous rather than the marginalized outcasts they are. It's not like there haven't been MAJOR scientific revolutions in the past, it's just that THOSE guys had incontrovertible hard data to back them up.

At first I thought you might just be a clever troll, but your tenacity on this subject goes far beyond the casual interests of a troll. I think you really believe all this, and rather than make me think you are an idiot, which you clearly are not, it makes me very curious about what makes you tick.

Re:What makes you tick, pln2bz?

[pln2bz]

Hey, it's my old friend! The memories ... ;)

The real issue at hand here is that the mainstream astrophysicists and enthusiasts today refuse to seriously consider the legitimate issues that Electric Universe Theory proposes. There is so little awareness on the mainstream side that the group as a whole is completely oblivious when an EU Theory is even validated -- which happens far more often than is being accepted. In order to confirm or deny a theory, it's important to first fully digest it. Even if the materials do not meet your typical requirements for mathematics, that does not necessarily imply that they are inherently false and unworthy of consideration. They are still ideas.

This constant insistence on peer review studies is a bit of a cop-out. It is really more of an excuse to prevent consideration of the theory by people who have come to depend upon the status quo. There are plenty of rather simple laboratory experiments that can validate the concept of electrical terra-forming -- especially with respect to Mars. I can go through the list, but few mainstreamers want to even hear about it.

The theory of uniformitarianism is slowly trending out of fashion. It's becoming increasingly acceptable within mainstream geology and archaeology circles that some sort of violent process could have occurred within human history. In other words, catastrophism is gradually being co-opted by the mainstream -- but without any consideration of plasmas, contacting plasma spheres or electrical interactions. It's generally thought that impacts are really just physical collisions, which lead to explosions. But there have been few attempts to actually demonstrate this by inducing an impact of some sort. The one attempt at an impact that has occurred -- the Deep Impact mission -- seemed to suggest a pre-impact flash that would correspond with the conjunction of two plasma spheres. But since other explanations exist, the mainstream astrophysicists gravitate to those other explanations. Rather than follow the anomalous data in an objective manner, they spend more time attempting to conform the data to mainstream theories.

If EU Theory wasn't true, then it would eventually become clear during the course of researching it. However, the sheer number of supportive details suggests that it likely is true. The more I read about it, the more this picture gets filled in. There are certainly gaps in the understanding and mathematical clarity, but there are no anomalies in EU Theory as there are within the mainstream circles. You will surely argue that this is because it's not a mature theory at this point in time, but that's not the point. The theory as a whole works quite well -- oftentimes better than the mainstream theories. There are actually many things that EU Theory explains that the mainstream theories avoid like the plague.

The idea that EU Theory says that there is no fusion occurring on stars is btw false. From http://www.electric-cosmos.org/sun.htm:

The z-pinch effect of high intensity, parallel current filaments in an arc plasma is very strong. Whatever nuclear fusion is taking place on the Sun is occurring here in the double layer (DL) at the top of the photosphere (not deep within the core). The result of this fusion process are the "metals" that give rise to absorption lines in the Sun's spectrum. Traces of sixty eight of the ninety two natural elements are found in the Sun's atmosphere. Most of the radio frequency noise emitted by the Sun emanates from this region. Radio noise is a well known property of DLs. The electrical power available to be delivered to the plasma at any point is the product of the E-field (Volts per meter) times current density (Amps per square meter). This multiplication operation yields Watts per cubic meter. The current density is relatively constant over the height of the photospheric / chromospheric layers. However, the E-field is by fa

Re:What makes you tick, pln2bz?

[Cheapy]

"Extraordinary claims require extraordinary proof."

I think any theory on the universe's nature would require extraordinary proof. My theory? Turtles, man. Turtles all the way down.

Re:What makes you tick, pln2bz?

[Short Circuit]

If fusion occurs where and how your sources says it is, it should be a simple matter to perform a laboratory-condition demonstration of this effect. If you can demonstrate fusion without the temperatures found at the center of the sun, I might be less disinclined to believe the EU concept.

Don't tell me none of the labs will touch it, though. At the very least, The EU folks should be capable of annoying "mainstream" scientists enough that some mainstream scientist would perform the experiment. Quantum mechanics annoyed Einstein and other physicists sufficiently that they came up with a thought experiment intended to discredit QM.

If such a thought experiment can be turned in favor of QM because of QM's merit (see a Slashdot article from last week or the week before about "spooky action at a distance"), then surely, if EU has merit, experiments intended to disprove EU can be turned in EU's favor.

Come back when that happens. If it already has happened, provide links to and/or names of actual papers, not more sites that describe the theory in layman's terms. Basing arguments on layman's terminology is disingenuous; An analogy can never be more true than the evidence.

Re:What makes you tick, pln2bz?

[Hognoxious]

Extraordinary claims require extraordinary proof.

I suppose you have some evidence to back that up?

Re:What makes you tick, pln2bz?

[pln2bz]

There are lower fruits to pick than the fusion experiment you discuss. All we have to do is take a look at the pictures that our probes are returning. As is, NASA demonstrates far more interest in the observations that confirm their current theories. There are in fact some very startling images coming back from Mars. Now that they've been placing many of these image databases online, it has really opened up the amount of geologic evidence for Electric Universe Theory within the solar system. Nobody has a monopoly on interpreting these images and I know for a fact that there are qualified geologists who are aligned with the EU group at this point in time that can technically analyze the observed surface features as well as any other mainstream uniformist geologist might. The EU Theorists have all sorts of supporters and researchers, some of which work at prestigious organizations. The problem is that very few of them can attribute their names to their analyses, for doing so would in many cases cause them to lose their jobs. This is no joke. It's a very delicate situation. You have no idea how much hostility exists towards any discussion of electrical terra-forming of planetary bodies. This is not an environment that's conducive to getting at the truth.

So, when you discount the www.thunderbolts.info Picture of the Day's as not meeting the expectations of a peer review process, you incorrectly presume that there is little technical skill available to the theorists. Some of the images that are being studied by the EU Theorists actually have no non-electrical explanation. We can see rilles on numerous planets that follow the topography both up and down. This singular fact should be sufficient to cause alarm for mainstream theorists, and yet, they are satisfied to completely ignore it. There is no tweaking of any mainstream theories that will allow rilles that violate gravity. It should be completely impossible by their own standards.

But more than this, the EU Theorists are having great success right now with reproducing our observations of Martian geology using plasma guns and very simple lab setups. A handful of papers have been published and are in the process of being published right now. Some of these experiments have been extremely low budget. It has been discovered, for instance, that the infamous Martian Spiders can be reproduced simply by dusting fiberglass onto an old VGA monitor and repeatedly discharging the screen with a finger. This process creates the precise morphology of the Martian Spiders down to a very fine level of detail. My understanding is that this paper has been submitted to IEEE, but I do not know if they will accept it.

There are also papers being published in a new emerging field called "plasma mythology". People on Slashdot will of course scoff at any attempts at developing a science of mythology, and it is a real shame because dramatic breakthroughs are occurring in this field. These guys are having some impressive successes in understanding ancient astronomical records, ancient texts and ancient mythologies by going back and re-interpreting everything within the context of a plasma cosmology. It turns out that there are amazing similarities in the descriptions of what ancients saw in the sky across all continents, and the things that they all describe, as if with one voice, are not possible within the context of a gravity-centric universe. They *only* make sense if electricity is playing a bigger role in the universe than is currently thought. And not only that, but they are different than what we see in our current sky -- implying that diffusion of ideas could not have possibly been the cause of the correlation between multiple, distant cultures, for it does not explain things that can be refuted merely by looking up into the sky.

One book in particular, God Star, by Dwardu Cardona, took 40 years to write and includes around 2,000 references. Dwardu's book started out as a bet 40 years ago that the Saturn Theory was so absurd that he woul

Re:What makes you tick, pln2bz?

[pln2bz]

"Extraordinary claims require extraordinary proof."

How would any of you possibly know that that proof has not been made? None of the skeptics here have actually read "The Electric Sky", "The Electric Universe" or "God Star". At most, the Slashdot crowd has only read a handful of Thunderbolts.info Picture of the Days. At least EU enthusiasts are aware of what both theories say. That's an important starting point for deciding which to believe.

Also, it's worth noting that there are numerous extraordinary claims made within astrophysics that never met the burden of extraordinary proof. The incredibly fast rotation of neutron stars; the concept of a black hole has had to change so many times that very little of the original theory is even left; the consensus that Venus is experiencing a runaway greenhouse effect; the idea that the cosmic microwave background represents the aftermath of an explosion; the idea that all redshift is the result of a doppler effect and the idea that quasars must be at the edge of space due to their unusual redshifts; the idea that planets and stars form by gravitational accretion ... None of these incredible assertions have met the standard of extraordinary proof, and yet consensus exists within the mainstream community on all of them. In order for us to meet the burden of extraordinary proof, we at a minimum must investigate alternative explanations of these phenomenon one at a time. But what actually happens is that much of what we believe about these things was formulated because no alternative was thought to be possible. EU Theory provides an alternative way of explaining all of these things and involves no invisible particles or forces. All that is necessary is to imagine that plasmas in space have a finite electrical resistance in space just like they do within the laboratory. Plasmas that contain less than 1% ionization will conduct electricity very well. That people would prefer to believe in invisible particles rather than a phenomenon we can characterize within the lab is pretty surreal. It's testament to the power of public relations. I guess the EU Theorists would have to cede that public relations is probably the most significant force within the universe.

Re:What makes you tick, pln2bz?

[Anonymous Coward]

As far as looking for an experiment with electricity, z-pinch fusion that actually supersedes the alleged core of the suns temperature by around 290million degrees..

Look no further then the Z-machine..

Which uses electricity, alot of it... to discharge through a barrel of wires, tungsten, steel, titanium etc... which turns them into a plasma and creates a Z pinch.. That pinch has fusion going on at the core for a brief time and temperatures exceed 300 million degrees, the fusion stops however, as the current that powers the pinch also stops.

I always laugh how people scoff at electricity's role in the universe, when any time they do anything related to actually duplicating the effects we see in space, they use massive amounts of electricity...

The mainstream is not objective?

[mangu]

they stack the cards very heavily in favor of mainstream theories. There is absolutely no attempt at objectivity.

So, you think that theories that are widely accepted by the experts in the field are less objective than those theories that are accepted by their creators alone? An interesting definition, I wonder what would you call a "subjective" theory...

Theories are not evaluated on the basis of their merit alone, but rather how well their creators can withstand a relentless series of withering attacks.

Psst, I have some bad news for you. The "merit" of a theory could be very well *defined* as how it can whitstand a relentless series of withering attacks. If it cannot do that, it has no merit. Any scientist pretty much expects to have every word he publishes put in doubt, tested, and re-tested. Every number he writes will be measured again and again by people all over the world who will refuse to accept his word for it.

In fact, the worst that can happen to a scientist is publishing a work about which no one expresses any doubt, because this would mean it's considered irrelevant. A relentless series of whithering attacks is what keeps any *true* scientist alive. Only crooks fear being put to test.

This is a trend that I believe was started back in the day of Carl Sagan

Ah, no, it's much older than that! This trend dates at least to Isaac Newton.

Re:The mainstream is not objective?

[pln2bz]

I was really trying to speak specifically about the atmosphere of BAUT. It is an extremely hostile environment. That is perhaps one way to get at the truth, but it presumes that mainstream astrophysicists are infallible. EU Theorists propose that mainstream astrophysicists have been improperly educated about plasmas. In that situation, the hostility is really just a barrier to objective consideration of their arguments.

But more than that, the EU Theorists are proposing a whole new approach to understanding the universe. They propose that any attempt to understand the universe must by definition be multi-disciplinary. All sources of information must be treated equally rather than as a hierarchy -- as the status quo does -- with astrophysicists at the top. The hierarchy might not be such a bad idea actually if it wasn't the case that astrophysicists have increasingly found themselves behind desks and at computers rather than in laboratories. But since this isn't the case, the hierarchy has become destructive. Now, it is considered normal for people that only do computer simulations and fiddle with numbers and equations to dictate to the experimenters what reality is. That's a mistake.

Another problem with this approach where we attack the argument instead of the idea is that it tends to favor smart people with mediocre ideas. Sometimes, in fact, mediocre people come up with some pretty smart ideas. We see this all the time in the technology world too.

Re:The mainstream is not objective?

[Anonymous Coward]

>they stack the cards very heavily in favor of mainstream theories. There is absolutely no attempt at objectivity.

So, you think that theories that are widely accepted by the experts in the field are less objective than those theories that are accepted by their creators alone? An interesting definition, I wonder what would you call a "subjective" theory...

>Theories are not evaluated on the basis of their merit alone, but rather how well their creators can withstand a relentless series of withering attacks.

Psst, I have some bad news for you. The "merit" of a theory could be very well *defined* as how it can whitstand a relentless series of withering attacks. If it cannot do that, it has no merit. Any scientist pretty much expects to have every word he publishes put in doubt, tested, and re-tested. Every number he writes will be measured again and again by people all over the world who will refuse to accept his word for it.

I know nothing about EU, but your attitude is exactly what he is talking about. It doesn't matter if the theory is accepted by others, it needs to be judged on merits. And it needs to be continued to be judged on merit just in case someone judged it wrong initially, or did not have enough data initially.

In the second part of your answer, you subtly switch from 'the ability of a creator to withstand an attack' to 'how well a theory can withstand an attack'. There is a big difference between those two and that was exactly what he was talking about.

It's about merits of scientific theories. It is not about scientists, their merits or their eloquence.

Re:The mainstream is not objective?

[hardburn]

I was really trying to speak specifically about the atmosphere of BAUT. It is an extremely hostile environment. That is perhaps one way to get at the truth, but it presumes that mainstream astrophysicists are infallible.

Nay, the whole scientific method is there to help remove human fallibility from the process.

Sometimes, in fact, mediocre people come up with some pretty smart ideas.

And "mediocre" people also come up with endless streams of perpetual motion machines, which are rapidly torn apart by properly applying the scientific method. Part of a good scientific education is to stop you from going down useless paths.

Re:The mainstream is not objective?

[Short Circuit]

The hierarchy might not be such a bad idea actually if it wasn't the case that astrophysicists have increasingly found themselves behind desks and at computers rather than in laboratories. And who do you think writes the simulations that they use? Simulations are procedurally-codified theories about how something works. Astrophysicists take a theory, write a simulation taking into account all the known variables, run it through the computer for a few days, look at the results, then try to find matching conditions using telescopes. If they find matching conditions, then they have evidence that their theory is correct. If they don't, then they have evidence that their theory is incorrect.

Their laboratory is the sky itself, and the telescopes they use. One of your posts talks about absorption lines. If you're going to make arguments based on absorption lines of stars, then you are implicitly accepting the same laboratory astrophysicists use, because you're accepting the same data astrophysicists use.

Now, it sounds like some of you are actively taking your theories and looking for relevant data. That's a good thing, just be willing to accept if/when some of your base assumptions turn out to be false. That's something "mainstream" science has had to deal with since the days when alchemists (Then "mainstream" scientists) believed that there four elements, two of which were different kinds of bile.

Take a look at the scientific process...it was described millennia ago, and has served up some kick-ass results. It doesn't really sound to me like you have a problem with the scientific process, but with astrophysicists specifically. If that's the case, ask yourself why. Does it have something to do with the fact that their theories can't be proven on a workbench and on a human timescale? How would EU, or any other theory at that scale, be any different?

Sometimes, in fact, mediocre people come up with some pretty smart ideas. Never, ever use that as an argument, justification, evidence or anything else. Those statements come across as pity pleas. Most of your complaints center around the perception that EU doesn't get any respect. Those complaints may or may not hold water, but then you turn around and come back with statements like this one.

You can have respect, or you can have pity. You can't have both. Respect gives your arguments life, pity leads people to ignore you.

Re:The mainstream is not objective?

[pln2bz]

Nay, the whole scientific method is there to help remove human fallibility from the process.

I'm curious which part of the scientific process is it that causes EU advocates to lose their jobs within the fields of astrophysics, plasma physics and geology when it's discovered that they are doing work that supports EU theory?

And "mediocre" people also come up with endless streams of perpetual motion machines, which are rapidly torn apart by properly applying the scientific method. Part of a good scientific education is to stop you from going down useless paths.

I suppose you believe that laboratory plasma physics is a "useless path"? You seem to be unaware that the EU Theorists are proposing that plasma phenomenon that we observe within the lab scale up to galactic scales. In the laboratory, plasmas are electrical phenomenon. The only thing standing in the way of space plasmas being electrical too are the astrophysicists themselves. They've been taught to believe in magnetohydrodynamics that nearly all space plasmas can instantaneously neutralize any charge imbalances and have frozen-in-place magnetic fields. They completely ignore the fact that sustained magnetic fields, in every other field of science, require the presence of an electric current. They treat magnetic fields as if they are separate entities that can store energy.

Rather than accepting the notion that the interstellar magnetic field, for instance, is being caused by an interstellar current, as Maxwell's Equations demands, the mainstream astrophysicists would prefer to invent an invisible particle called dark matter to explain galactic rotation curves. We can explain those curves using nothing more than electrical plasmas in plasma physics. This is not even an inherently testable theory. It's not good science, and mainstream astrophysicists have surprisingly few successful predictions to point to that can validate their theories. They completely ignore the fact that Wallace Thornhill correctly predicted nearly all of the results of the Deep Impact mission to Comet Tempel 1 -- results which continue to baffle NASA scientists. It's not possible that he could have so accurately predicted those results by accident. The prediction was far too detailed.

Re:The mainstream is not objective?

[pln2bz]

Their laboratory is the sky itself, and the telescopes they use. One of your posts talks about absorption lines. If you're going to make arguments based on absorption lines of stars, then you are implicitly accepting the same laboratory astrophysicists use, because you're accepting the same data astrophysicists use.

The fact remains that 99.99% of all visible space consists of matter within the plasma state. If you want to understand the universe, therefore, it makes complete sense to study plasmas within a real laboratory where we can create controls. EU Theorists have no problem with some of the incredible technologies that have been developed for observing space phenomenon. The problem has been the interpretations of space observations, which consistently categorize electricity in space as a second-order phenomenon -- little more than a side effect of other processes happening. And yet, each time we build new probes and telescopes, we continue to make observations that support the notion that electricity in space *is* doing things of great importance.

Mainstream astrophysicists aren't even aware, for instance, that the bipolar symmetric morphology is the classical z-pinch electrical plasma morphology. We see this shape in various manifestations time and time again, and there is rarely any realization that plasma physicists have no problems generating them in the lab. We observe jets of matter that appear to be light years in length coming out of black holes. We see numerous rilles on planets that follow the topography of the land both up and down, in defiance of gravity. We see electrical torus rings surrounding the equators of pretty much all bodies in space. We see cloud movement on planets that is far too fast and much too far from the Sun to be explained by solar heating. We now see upper atmosphere lightning here on Earth, which suggests that lightning is a part of a much larger solar system circuit. We see a stream of protons and electrons moving into both poles of the Sun. We see dust devils on Mars that have lightning bolts at their cores, and we now have images of the edges of Martian dust storms that demonstrate that those dust storms are actually armies of dust devils. We can replicate the precise morphology of Io's plume in the laboratory with a plasma gun, and pictures that have been returned of Io are absolutely indistinguishable from Kristian Birkeland's old terrella experiments. The solar wind continues to accelerate as it moves past the planets and the Sun's corona is around 100 times hotter than its surface. We can explain pretty much the entire HR diagram in terms of laboratory plasma physics. Comet researchers have had virtually zero success in finding traces of volatiles on the surface of comets, and the streams of apparent OH coming off of them can be easily explained with electric machining of oxygen atoms off of the comet, which then combine with Hydrogen protons from the solar wind. There are currently discussions within EU circles about the Aether Physics Model, whose creator has successfully predicted all of the electron binding energies for the entire periodic table based upon an aether theory that is compatible with EU Theory. I haven't even started talking about all of the advances that have been made in understanding ancient astronomical records, ancient texts and ancient mythologies. When re-interpreted within the context of a plasma cosmology, many of these writings formulate a single, coherent story that spans multiple continents and describes a sky that looks nothing like the one we see today.

Actually, it's quite clear that people will argue against Electric Universe Theory regardless of what it says or what evidence supports it because people refuse to read what it says.

Different perceived orders cannot affect causality

[Dogtanian]

Does that mean that cat I ran over last night in my car was not necessarily born yet so I didn't really run over it ? Phew, I was having a bit of a guilt trip.... Disclaimer: IANAP (I am not a physicist; in fact I'm very, very far from being one).

My understanding is that according to the theory of relativity it's perfectly feasible for two separate events to be seen occurring in different orders, depending on where they were viewed from.

Why doesn't this affect causality, nor apply to your cat? Because this can only happen in cases where neither event could have caused the other. Nothing can travel faster than light, including the effects of a given event. And in such cases, regardless of the perceived order of events, the distance between them is too great for the effects of the "first" to reach the position of the "second" before that happens.

So, you're probably thinking "Which one *really* happened first?" But there's no absolute "correct" answer. A viewer at one point may have seen "A" before "B"; someone at another viewpoint may have seen "B" before "A". Relativity tells us that there is no "correct" frame of reference and that both perceptions are equally valid. I assume that this is what the GP meant by there being no universal timeline.

Relativity is cool. :-)

Re:How to figure out which star you are looking at

[Bender Unit 22]

Yet another place. cool :) thanks!

Re:Different perceived orders cannot affect causal

[ozzee]

Relativity is cool. :-)

What do you think the probablility is of photons showing up soon will describe Eta C. blowing up ?

That's not a star . . .

[StefanJ]

It's a very, very large gamma ray laser, created by a very patient race with an enemy living in a globular cluster whose orbit around the galaxy will take it into the path of the polar emission stream.

The other pole's stream will be redirected with a vibrating unobtanium mirror and used to paint advertising slogans in a gas cloud on the edge of the Lesser Magellanic Cloud.

As any good astronomer knows...

[rholland356]

...you can make a career out of predicting the death of one particular star...

Be glad to. You see, you're confused...

[msauve]

because the sun doesn't rise, the horizon sets. HTH! HAND!

Re:Be glad to. You see, you're confused...

[Doctor Memory]

I know! Let's stand him on his head!

There, you see — it's morning!

Effect on Climate?

[tjstork]

There are some climate theories that argue that the driver behind our climate change is that the solar wind is shrinking up, allowing more cosmic rays in and effecting cloud formation. What happens if this star blows up and we get the shock wave from it? Could there already be nebula on its way to us to choke our solar system with so much cosmic dust?

I negelected to mention I was travelling that way

[benhocking]

Although it's only a light day away from me, I'm traveling in the opposite direction. So, you see, it won't go supernova for a long, long time.

Speed of causality

[Roger W Moore]

After all, the speed of light is really just the speed of causality.

No, the speed of light is the MAXIMUM "speed of causality". A causal connection between events can happen at less than the speed of light. A simple example is hearing thunder sometime after seeing the lightning strike in a thunderstorm. The connection between the two events (lightning flash and the thunder) propagates at ~330 m/s (the speed of sound in air). All relativity tells you is that the connection between two events cannot propagate FASTER than light i.e. you cannot detect any effect of the lightning before it is visible.

Re:Speed of causality

[Short Circuit]

you cannot detect any effect of the lightning before it is visible. Nitpick: "Visible" is not the correct word here. There is electric current flowing before the air becomes hot enough to be incandescent.

Of course, now we're talking about predicting an event based on timely evidence strongly correlated to its occasion.

Re:Speed of causality

[Roger W Moore]

However that is not what creates the "bang" so it is not the event that we are interested in (as you point out). However there is a nitpick you could have had: the speed of light in air is slightly slower than the speed of light in vacuum (by a very small amount) and so theoretically you could transmit a signal that would arrive slightly before you can see the lightning since it is only the speed of light in vacuum that is fundamental.

Re:Speed of causality

[Short Circuit]

I would argue that, in this scenario, the heat generated by the electric current is the instigator for both the bang and the flash. The bang doesn't arise from the incandescence, but from the increased air pressure derived from the heat. The incandescence also derives itself from the heat.

We're not talking about a chain of events, but a tree. The pressure increase and incandescence are independently caused by the heat. One doesn't cause the other, they're both symptoms of the same underlying phenomenon.

But enough nitpicking. There's plenty of other interesting conversation attached to this article. :-)

Re:anywhere from today while i am typing to 10M yr

[Maserati]

That's a fun read. Hamilton writes excellent technothrillers and there are some very neat concepts in that one (and the one sequel). He also has some of the best set-piece action scenes in contemporary fiction. I liked the Night's Dawn series more, but this one is still a damn good read.

Re:anywhere from today while i am typing to 10M yr

[stoolpigeon]

I've really enjoyed everything of his that I've read so far. I have not read the sequel yet to Pandora's star. The endings are the only thing thats not on the same level as the rest.

Re:How to figure out which star you are looking at

[Platupous]

Bender Unit 22,

You are uncommonly friendly for a bending unit, have you an emotion chip installed?

Or maybe you just want to get close enough to steal my wallet ehh?

One close call!

[Anonymous Coward]

When stars like Eta Carinae explode, they tend to shoot of beams of energy and matter that, at its distance of 7500 light years, could kill every living thing on Earth.

Wow... talk about a close one

Stellvia of the Universe indeed! @_@

Uh, end of the world?

[trawg]

I thought this was interesting, at the end of the article:

When stars like Eta Carinae explode, they tend to shoot of beams of energy and matter that, at its distance of 7500 light years, could kill every living thing on Earth. But since it's pointed away from us, all we'll get is a spectacular light show. If you're keeping score at home, gamma-ray burst aimed at you = bad, pretty supernova with no accompanying high energy radiation = good. Little bit scary to think about!

Re:Uh, end of the world?

[Anonymous Coward]

well, the accompanying burst of energy and matter would arrive only 7500 years later at best, so we won't be here to witness it anyways.

We're all going to die!

[Anonymous Coward]

If a pole is pointed this way. Which it might be, if it has precessed.

Or will it just be everyone and everything in the southern hemisphere who dies?

Re:anywhere from today while i am typing to 10M yr

[Maserati]

Nobody who complains about the ending to Night's Dawn has a better idea :-)

This new series has a better ending though.

Don't you watch movies?

[Anonymous Coward]

This thing already exploded in 1977. That's when Alec Guiness felt a great disturbance in the force. It was actually a red star by the time it exploded because Superman arrived a few years later...

Re:How fast are the gamma rays moving?

[grikdog]

To answer the original question: Yes, at the speed of light, but presumably any gamma radiation reflected off gas clouds on the side of Eta Car farthest away from Earth will appear a bit red-shifted. This is left as an exercise for the reader.

oblig. futurama quote

[holywarrior21c]

freeze!! i am gonna microwave a whole bag of popcorn with aluminum foil seal!!

Scientists generally do resist novelties

[jenik]

and sometimes the new findings win the majority over and we have a paradigm change and sometimes they are just ignored. See T.S. Kuhn's Structure of Scientific Revolutions. P.S. I am a scientist.

Ob

[edittard]

they really mean it probably exploded 6,500 to 7,500 years ago and we're awaiting the story on Digg/Ars Technica

Fixed.

No guarantee it'll miss us entirely

[Anonymous Coward]

We're pretty sure this will be along the same axis as those two lobes which blew out in the 1800s. So they'll miss us.

I hope that the book has a LOT more coverage on impact assessment than that, or it'll be saying pretty much nothing.

The fact of the matter is that nice tidy geometrical explosions are almost never seen, and despite the preferential directions, real supernovae have pretty messy burst lobes. I hope that a representative set of known explosion patterns are analysed to give an idea of the range of possibilities, and not just the single "we appear to be safe" scenario. Statistically, it's not that clearcut at all.

Re:Different perceived orders cannot affect causal

[Dogtanian]

I've absolutely no idea.

No. If you'd review your time travel verb tenses

[ElboRuum]

You'd see that in this case, you need to use the future past perfect subjunctive, which would be:

"The star is about to will had haven been exploding."

Damn good thing too

[Archtech]

You do not want to be anywhere near something like this:

http://www.nagt.org/files/nagt/jge/abstracts/Dutch _v53n1.pdf

Re:anywhere from today while i am typing to 10M yr

[stoolpigeon]

oh yeah - i couldn't do a better job with any of it. and as things built up I was wondering all the time, "How is he going to resolve all this?" so you have a very good point - I guess it just bugged me more after I read Fallen Dragon and ran into the same thing again - basically. But I think Hamilton is an incredible writer with amazing ideas that are really quite fresh and original - not just retreads of what was already done before.

Except that...

[Anonymous Coward]

How about this: even though this expected supernova happened thousands of years ago, for all causal purposes, it won't have any effect upon us until we can see it. After all, the speed of light is really just the speed of causality.

So, in a local causal sense, it hasn't happened yet. The distance just means that if we thought to have any influence on it before it happens here, we'd have to have done something thousands of years ago or longer to exert a causal influence.

The light from the supernova hasn't reached earth yet, and yet the supernova explosion has ALREADY had a causal impact here. I mean, it's already spawned a slashdot thread. Spooky!

Mentioned by Carl Sagan in Cosmos

[localroger]

Leading to the memorable line: "An Age is not Dark because there is no light, but because we refuse to see the light."

Re:Mentioned by Carl Sagan in Cosmos

[Bramantip]

The worst darkness is ignorant of history, and to calumniate one's ancestors. If we know more now, it is only because we build upon the achievements of the past. The theories of Isaac Newton would not have been possible if it were not for such men as Bernard of Clairvaux, Anselm of Cantebury, Thomas Aquinas, and a host of persons who lived in the so-called 'dark ages'. Even Aristotle, so vilinised by Sagan actually predates Galileo's theory of inertia by 1800 years. Quotation:

Further, in point of fact things that are thrown move though that which gave them their impulse is not touching them, either by reason of mutual replacement, as some maintain, or because the air that has been pushed pushes them with a movement quicker than the natural locomotion of the projectile wherewith it moves to its proper place. But in a void none of these things can take place, nor can anything be moved save as that which is carried is moved.

Further, no one could say why a thing once set in motion should stop anywhere; for why should it stop here rather than here? So that a thing will either be at rest or must be moved ad infinitum, unless something more powerful get in its way. (Physics IV, 8)

Carl Sagan actually wrote a lot of science fiction, which have little or nothing to do with reality but one's own dreams. Often one doesn't see the light simply because one prefers one's own dreams instead of reality.

Short Story

[lymond01]

I forget who wrote it, but there was this short story about a prediction in the 15th century of a particular star who's supernova light would reach Earth in a certain year in the 20th century. The astronomers would go out night after night trying to find it. Then, past midnight, one person says, "Is it getting warm?" Meanwhile a huge glowing object comes up over the horizon, practically turning night into day. "Is that it?" one asks. "No...that's the Moon. It is the hour and minute of her rising."

And then it begins to get very warm. They begin to realize that this incoming supernova's energy will surpass the Sun. They retreat indoors and, as their side of the Earth revolves to face the supernova, it rises as a furnace to our planet, twice as large as our sun. Anything flammable combusts, oceans grow turbulent as they begin to evaporate, anyone not reaching some sort of shelter dies in the street. Even those that do make it indoors cannot survive for long the 180 degree air. One scientists survives until nightfall where the temperature drops to 140. He muses on what life will survive this on our planet. It won't be humans.

Time Ordering of These Events is Subjective in SR

[internic]

First, let me say that there's really no problem with the statement that the star has probably already gone supernova and we just haven't seen it yet. That's a perfectly reasonable thing to say that refers to things according to the time and space coordinates of our frame of reference here on Earth.

However, it is true that according to special relativity, this is a subjective statement. An observer moving relative to us in the right way would disagree. In his frame of reference the supernova explosion has not happened yet by the time this story went up on Slashdot. This is because the two events, the story being posted on Slashdot and the star going supernova, are space-like separated, which is to say that you'd have to go faster than light to be present at both events and one cannot directly influence the other. When two events in spacetime have space-like separation, they don't have an objective ordering in time, observers in different reference frames may disagree about which happened first. Any statement about the timing of such events is a subjective statement that depends on the observer's frame of reference. If the events had a time-like separation (like any two events that affect one another) then their time ordering would be an objective fact that all observers could agree on.

For more detail on this topic, please see my articles on relative simultaneity and the light cone of an event (where I try to explain this clearly) or consult a book on Special Relativity. General relativity probably isn't very relevant here.

Re:i've been

[MobileTatsu-NJG]

"...rubbing my dick on pictures of bob saget, and i'm ready to explode real soon now, too." ... and the name of this show, The Aristocrats!

I really can't believe how contraversial that post was.

Re:Time Ordering of These Events is Subjective in

[IWannaBeAnAC]

Are you confusing observation of events (which in general different observers will disagree on which happens first), with proper time in an inertial frame?

Firstly, the case of Earth and Eta C is special because they are (approximately) not moving relative to each other and are therefore in the same inertial reference frame. Since this is an inertial frame, we would we able to observe a clock on Eta C going at exactly the same rate as a clock on Earth, just 7500 years slow.

An observer moving relative to us in the right way would disagree. In his frame of reference the supernova explosion has not happened yet by the time this story went up on Slashdot.

That statement is really weird. For a start, on Earth we have not yet observed the supernova explosion, so I'm not sure what the disagreement is supposed to be. Secondly, an observer wouldn't have to be moving relative to us in order for him to observe the explosion before observing this slashdot story, he would just need to be in a different location. 1000 light-years away from us in the direction of Eta C would be plenty - he would have seen the explosion already but he won't see the slashdot story for another 1000 years. But in all cases, any observer would be able to say with certainty that in the inertial frame of the Earth and Eta C, the supernova happened before the Slashdot story, even if they observe them in a different order. In the case of the spaceman 1000 light-years away from us, his reasoning would be (at time 1000 years in the future, when he observes the slashdot story), "I just saw a new slashdot story was posted about Eta C. The message has travelled 1000 light-years, therefore the Slashdot story was posted 1000 years ago. But 1000 years ago, I saw Eta C go supernova. Eta C is 6500 light years away, therefore Eta C went supernova 7500 years ago.". Note that an observer on Earth, 1000 years in the future, would come to exactly the same conclusions - namely that the slashdot story was posted 1000 years ago and Eta C went supernova 7500 years ago! To emphasize, this is possible only because Earth and Eta C are in the same inertial frame.

Re:Time Ordering of These Events is Subjective in

[internic]

Are you confusing observation of events (which in general different observers will disagree on which happens first), with proper time in an inertial frame?

I am talking about when things actually happened according to observes in different inertial frames. I'm not talking at all about when they were observed. Note that we're talking about coordinate time in a particular reference frame not the proper time (which means something particular in SR), so let's not get further confused there.

...on Earth we have not yet observed the supernova explosion, so I'm not sure what the disagreement is supposed to be. Secondly, an observer wouldn't have to be moving relative to us in order for him to observe the explosion before observing this slashdot story...

Again, I'm not talking at all about when things are observed. I'm talking about when they actually happened according to various observers (which they would deduce from when they observe something, how far away it is, and the speed of light).

But in all cases, any observer would be able to say with certainty that in the inertial frame of the Earth and Eta C, the supernova happened before the Slashdot story, even if they observe them in a different order.

Everyone will certainly agree on what the time ordering is in a specific frame of reference. What I said is that someone in a different frame of reference will say that, according to his own time keeping, the Slashdot story was published before Eta C went supernova. It is not just that he will observe them in this order, he will say (according to the time in his frame of reference) that they actually happened in this order. One such observer would be someone in a space ship passing by Earth at the instant the story was published moving at 0.99c away from Eta C. You can verify this using the Lorentz transformations.

Relative simultaneity and these related concepts are highly unintuitive and often difficult to understand at first. A common misconception when learning about SR is that it's all just about when things were observed not about when they actually happened. Like I said in the GP post, I wrote some articles that I hope might clear this up a little, or you can read a physics book that treats SR (some are listed at the end of those articles).

Re:Time Ordering of These Events is Subjective in

[IWannaBeAnAC]

Note that we're talking about coordinate time in a particular reference frame

Right - here the obvious reference frame is the inertial frame in which both the Earth and Eta C are stationary.

Again, I'm not talking at all about when things are observed. I'm talking about when they actually happened according to various observers (which they would deduce from when they observe something, how far away it is, and the speed of light).

Exactly. We're on the same wavelength here.

Everyone will certainly agree on what the time ordering is in a specific frame of reference. What I said is that someone in a different frame of reference will say that, according to his own time keeping, the Slashdot story was published before Eta C went supernova. It is not just that he will observe them in this order, he will say (according to the time in his frame of reference) that they actually happened in this order. One such observer would be someone in a space ship passing by Earth at the instant the story was published moving at 0.99c away from Eta C. You can verify this using the Lorentz transformations.

This is where we have a fundamental disagreement. When the observer calculates the time at which Eta C went supernova, he would of course take into account the fact that he is moving away from it at 0.99c (ie, he would calculate the proper time in Eta C's frame of reference). It doesn't make any sense to do otherwise. Suppose, for example, there is an observer on Eta C. In 7500 years he will observe the Slashdot story and, simultaneously (as in at the same coordinates in spacetime, so everyone can agree it was simultaneous) the space ship passing by. Now suppose that 10 minutes later, the observer on Eta C sees the space ship blow up. Now, given that the observer on Eta C has seen 10 minutes elapse, how long was the spaceman travelling for since he left Earth? The answer is of course much less than 10 minutes, it is about 1.4 minutes.

The fundamental point, which you seem to be missing, is that Earth and Eta C are both in the same inertial frame, and within an inertial frame simultaneity is well defined. If some other observer is flying past in his spaceship, he can still determine whether the two events are simultaneous or not because there is a unique inertial reference frame in which both objects are stationary, he just has to do a Lorentz transformation into that frame. In other words, a clock on Earth will move at exactly the same rate as a clock on Eta C, so the time difference between an event happening on Earth and an event happening on Eta C is well defined, and everyone will be able to agree on what it is (after they do a Lorentz transformation to the common inertial frame).

The case where simultaneity is not well defined is when the Earth and Eta C are moving relative to each other. In this case, the spaceman flying past cannot determine an inertial frame that is common to both objects. He could choose a frame in which Earth is stationary, or he chooses a frame in which Eta C is stationary, but neither is any help in answering the question of whether the events were simultaneous.

Don't do this around astronomers

[Tablizer]

http://nedmartin.org/amused/pics/son-of-a.jpg

Since when si one novel "a lot?"

[localroger]

Carl Sagan actually wrote a lot of science fiction

Sagan wrote exactly one fiction novel, Contact. He was a pure research scientist who published peer-reviewed papers, and a popularist who wrote essays and nonfiction books and produced a wildly successful nonfiction PBS series.

Might want to check out that log in your own eye, etc.

Re:Since when si one novel "a lot?"

[Bramantip]

Carl Sagan's gift was for the popularizing of science, not so much for actually doing science himself.

True that the book "Contact" is the only ostensibly science fiction work, nonetheless I would classify his many musings on intelligent life on other worlds as part of science fiction as of yet there is absolutely no evidence for it - observable and repeatable experimental data as being one of the criterion for true science. Thus most of his work would be classified as non-scientific in this sense.

Here is a list of his published works that I have found. Almost all of them concern 'personal refections', 'speculations', 'vision of human future in space', etc. This is not science, but personal reflection, even fiction.

One quote gathered from google says that he wrote some 600 peer-reviewed papers, but I have yet to find a single one available on the internet.

Uh, Clem?

[msauve]

Did you break the president?

Re:anywhere from today while i am typing to 10M yr

[SEWilco]

As this star is already emitting nitrogen, if it vanishes from view then someone has built a bomb casing.

Re:anywhere from today while i am typing to 10M yr

[SEWilco]

Don't forget to broadcast the images live toward other stars, in case we're wrong about the radiation blast not hitting us. Maybe someone else will be able to watch what happened just before the telescope, camera, transmitter, power lines, and the power plant generating its electricity, melted.

mod parent down

[Anonymous Coward]

Uh... I see why the GP post was moderated funny. Why was this one? Even to the point of +5.

His specialty was planetery atmospheric science

[localroger]

Surely you remember the worries about nuclear winter? He was the S in the TTAAPS paper that started that.

And musings are not fiction. This is a musing:

Aliens probably exist out in the universe; let me tell you why I think so.

This is fiction:

I was abducted by an alien the other day. It had one I, one horn, it could fly and it tried to eat me.

See the difference?

Re:Time Ordering of These Events is Subjective in

[internic]

The fundamental point, which you seem to be missing, is that Earth and Eta C are both in the same inertial frame, and within an inertial frame simultaneity is well defined.

I'm certainly not missing that. I never claimed otherwise. I only said that in the coordinate time of another frame the time ordering would be different. The rest frame of Earth and Eta C is, according to relativity, in no way special and the time ordering in that frame is no more the "correct" time ordering than is that observed in my hypothetical rocket ship's frame. That is certainly the way relativity is understood among physicists, which you can verify by looking at basically any book on relativity. But anyway, this now becomes a semantic point that's not worth debating. Finally, I'll point out that, like most celestial objects, Earth and Eta C actually have some nonzero velocity relative to one another, so there actually exits no mutual rest frame (however, if one were intent on trying to pick some "special" frame of reference, one could, I suppose, pick the center of mass rest frame).

Re:Different perceived orders cannot affect causal

[Man Eating Duck]

it's perfectly feasible for two separate events to be seen occurring in different orders

For a simple explanation with animations of one such case, check this: http://www.puttypeg.com/train.html
It's a perfect link to send to someone in response to "Physics? But that's boring!" :)