Astronomer Discovers the Most Distant Stars Ever Observed From Earth

Cryolithic writes to tell us The Vancouver Sun is reporting that a University of B.C. astronomer recently used NASA's Hubble telescope to see a cluster of stars one billion light-years from Earth, the farthest stars ever observed from Earth. From the article: "That's interesting, he explains, because given that light travels at a finite speed -- 300,000 km a second -- the light emitted from the star cluster he and Kalirai saw was emitted one billion years ago. That means the cluster as it appeared to them two months ago was the way it looked one billion years ago. In other words, they were looking one billion years back in time."

Comments

Looking back in time.

[Anonymous Coward]

"In other words, they were looking one billion years back in time."

So, when I look at the sun, I am actually looking back in time 8 minutes?

Deep.

Re:Looking back in time.

[User 956]

So, when I look at the sun, I am actually looking back in time 8 minutes?

Yes, and apparently, 8 minutes ago hurts like a motherfucker.

Re:Looking back in time.

[Gospodin]

When you read Slashdot, you are looking back in time approx. 1.7e-9 seconds*, assuming you sit about 50cm from your screen.

* May be more if you're reading a dupe.

Re:Looking back in time.

[Anonymous Coward]

Brought to you by: http://www.google.com/search?hl=en&q=50cm%20/%20c

Re:Looking back in time.

[Abcd1234]

And you know what's really weird? If the Sun just winked out of existence right this minute, the Earth would continue in it's orbit for 8 minutes before flying off into space. Why? Because gravity also propagates at the speed of light.

Re:Looking back in time.

[Enzo the Baker]

Anyone who has ever watched a Roadrunner vs. Wyle E. Coyote cartoon knows this.

Re:Looking back in time.

[Goaway]

Yeah, no, maybe. Depending on how fast you're moving. And stuff. Relativity is tricky. Even something as simple as this causes your everyday intuition to fail.

Re:Looking back in time.

[Goaway]

No. Because you can't send it quick enough.

Re:Looking back in time.

[Doc Ruby]

I'm not sure that the "gravitons" postulated to execute that lightspeed limited coupling have been proven to exist. I know it was a subject of much speculation late at night while I was in college in the late 1980s.

If gravity also travels at lightspeed, I wonder whether space would "unwarp" around the Sun instantly. Or whether there's some "viscosity", with the Sun's gravity well taking some time to "snap" into an undeformed, thereby gravityless, shape in 3D (4D) around the Sun. Probably it's instantaneous, but we don't know that much about the "void medium" in which these fundamental forces act. At least I don't know that much :).

Re:Looking back in time.

[G00F]

That is not fact. It is unknow if we are orbiting where we see the sun, where the sun truely is, or something in between.

It's speed is unknown, its fast/instant, but nothing can be faster than C (the speed of light) so it must match that? Or maybe it is a little slower.

We are still trying to figure out gravity and it's effects on light, time, and other objects. It's harder to test than light because you will always have gravity, no matter how small. Can't just set up a spinning mirrior on a remote mountain and beam a light at it.

Re:Looking back in time.

[The_Wilschon]

Because gravity also propagates at the speed of light.

We don't know this. Sure, it is predicted to be the case by GR (I think. High energy physicists don't have to know much about GR, and I don't.), but we have not measured the speed of gravity in any sort of reasonable experiment. Clifford Will, at Washington University in St. Louis, says that we need to detect gravity waves before we have any sort of reasonable measurement of gravity's propagation velocity.

From the bottom of the linked page:

The real way to measure the speed of gravity is to detect and study gravitational waves. By comparing the arrival of a gravitational-wave signal with that of an electromagnetic signal from an astrophysical source, one could compare the speed of gravity to that of light to parts in 10^(17).

Of course, I don't know Dr. Will personally. I merely turned up his page via Google, but WashU is certainly a respectable physics school, and I am inclined to trust what their faculty say about matters which are in their particular area of expertise and out of mine.

Re:Looking back in time.

[Abcd1234]

It's simple: as far as I know (and feel free to correct me if I'm wrong), instantaneous gravity would allow instantaneous transmission of information. This directly contradicts relativity, and so I think it's pretty presumptuous to assume that gravity propagates faster than c.

Re:Looking back in time.

[Abcd1234]

We don't know this.

*sigh* Yes, I know, I was simplifying things. The current thinking is that, odds are, gravity propagates at the speed of light. It may propagate slower. It almost certainly does not propagate faster (lest our current cosmological theories fall flat on their face, as they make the fundamental assumption that information can not travel faster than c), and *that* is, I think, the real brainf*ck for most people.

Re:Looking back in time.

[Doc Ruby]

I don't know how it might relate to gravity, or that it in any way demonstrates "instantaneous gravity", but quantum entanglement suggests (even demonstrates) that some info is transmitted faster than lightspeed. That's one reason Einstein called it "Spooky Action at a Distance", and one reason he rejected all quantum mechanics as a fallacy. Even if its model has proven more accurately predictive of phenomena than relativity, AFAIK.

Re:Looking back in time.

[Abcd1234]

but quantum entanglement suggests (even demonstrates) that some info is transmitted faster than lightspeed

No, it doesn't. There is a No communication theorem, which basically outlaws the possibility of transmitting *any* information (instantly or otherwise) via QE.

Re:Looking back in time.

[mikael]

Some inventors have proposed creating communication systems using gravity waves. Such a system only requires a large weight to be shifted according to sound vibrations. Detecting the resulting gravitational wave is the hard part.

Re:Looking back in time.

[axllent]

After you pissed off Jack Bauer...

Re:Looking back in time.

[Doc Ruby]

No, that's Anonymous Coward "quicquid mechanics", not the precisely predictive QM.

Re:Looking back in time.

[Doc Ruby]

Yet QE has been demonstrated to sync distant particles faster than lightspeed communication would allow. I'm illiterate in the math in that Wikipedia page, but how does it account for the measured results?

Re:Looking back in time.

[usmc1944]

You didn't know that? I don't know in the U.S. but I learned that in 2nd grade in Italy, so I find the above line in the article to be a little too "obvious"

Re:Looking back in time.

[Abcd1234]

Incidentally, feel free to read about the EPR Paradox, which essentially precludes instantaneous communication thanks to QE.

Re:Looking back in time.

[Doc Ruby]

No, I'm asking critical questions from what I do know, despite my ignorance, which I have expressly stated. That's "science".

I asked you to explain how recent demonstrations of QE are explainable despite the "No Communication" theory you offered. I don't think you've explained that, even in that last message, which just seems to deny that the QE was demonstrated. Which counters the reporting I've read, even though it's been in layman's terms.

If you don't want to talk to people who have some degree of ignorance, but want to understand what you claim to know, then you're not cut out for science. You should look into blogging.

Re:Looking back in time.

[IngramJames]

When you read Slashdot, you are looking back in time approx. 1.7e-9 seconds*, assuming you sit about 50cm from your screen.

What are you, a creationist? You haven't factored in the time it takes for the packets to travel from the server to my PC! That increases the timescale orders of magnitude! You can get, TCP/IP fossils in that time, no problem!

Re:Looking back in time.

[vindimy]

No. Because you can't send it quick enough.

Why not, because you said so?

Read about the latest advances and theories in quantum physics and stop relying on Einstein. this is so last century! What else you're going to say, we can't fly 'cause we're heavier than air??? In his times, so many things were considered impossible that we're now taking for granted. Like, quantum physics and the latest advances and theories ;).

Peace out and keep your eye on this.

Re:Looking back in time.

[Xamataca]

"e pour se muove"

Re:Looking back in time.

[dangitman]

Except you aren't traveling. You haven't gone anywhere or anywhen. You also aren't even observing the past, you are observing the present - the light waves as they are currently striking your eye. Just because they traveled for a while doesn't mean you are seeing the past.

It's like saying if someone visits me from China, I have traveled back in time the 12 hours that it took for them to reach me. In other words, it's total nonsense.

Re:Looking back in time.

[LionMage]

Nobody's denying that Quantum Entanglement happened. The denial is of the interpretation that you seem to insist is the only valid interpretation of the experimental evidence.

Being able to flip the state of a particle at location A and observing a corresponding state-flip of an entangled particle at location B doesn't mean that meaningful information has been transmitted, despite what your intuition might tell you.

In other words, the measured results (which, by the way, you failed on 3 occasions to provide a citation for) do not mean what you think they mean. So for you to ask, "I'm illiterate in the math in that Wikipedia page, but how does it account for the measured results?" is kind of problematic from a couple standpoints. First, math is the language of science, and if you can't understand the math, you haven't a prayer of fully appreciating any answer that anyone could provide you with. Second, you've made an intrinsic assumption that you understand what the "measured results" of these Quantum Entanglement (QE) experiments are, and what these results mean.

So I would ask that you provide specific links to the specific experiments to which you are alluding, rather than making vague hand-waving references to "reporting [you've] read." You're not really asking critical questions based on what you know, you're asking critical questions based on what you think you know, and the only way for us to directly address this and answer your questions is for you to do us the courtesy of being as specific with us as we are with you. Getting petulant isn't going to gain you any satisfaction.

Based on the No-communication theorem (linked previously), we know that statistically, it's impossible to distinguish between an intentional state change at the receiving end and a random state change. We also know from Heisenberg's uncertainty principle (which I'm sure you've read about somewhere) that measuring any state of an entangled particle with any degree of precision will modify other quantum state information in unknowable ways. In addition, the state of the complementary particle in the entangled pair gets modified as well.

Because of this "noise," the best you can hope for is a statistical understanding of what's going on. Statistics is based on aggregate behavior (averaging over time, or averaging over many members of a population, for example). Any "signal" that might be there will be drowned out by noise.

It's worth noting that if you follow Wikipedia links, you'll eventually wind up at articles about quantum cryptography and the EPR paradox. The quantum crypto article is interesting because it directly addresses some of the questions you have, since quantum crypto can be made to rely on particle entanglement... which would seem to bolster the interpretation that you favor, but read closer: Even though you don't have 100% confidence in the "signal" that is being sent from location A to location B because of the statistical issues previously raised, you can have a greater-than 50% probability of correctly deducing the state of the "sender." An eavesdropper will reduce this probability below the 50% threshold, in such a way that the eavesdropping is detectable. And even saying all this, I've actually somewhat mis-stated how this is supposed to work in an effort to simplify it. It's not so much that someone is twiddling particle A and someone else is measuring particle B; it's more like someone is making measurements of particle A, and someone else is measuring particle B, and because of entanglement, those measurements are going to correlate some percentage of the time...

Re:Looking back in time.

[FormOfActionBanana]

Detecting is the COOL part, because mass (like oh, the Earth) doesn't shield the waves. In addition, you can make a focused beam by moving the impellor along only one axis.

I think there's a possibility that if you can shake the weight quickly, like femtoHz or something, detection is feasible with a small needle.

Re:Looking back in time.

[Goaway]

Faster-than-light communication would create paradoxes if it happened in this universe. No new development is going to change that. General relativity is a completely different and totally groundbreaking theory when compared to Newtonian mechanics, but apples still fall like they always did even though we discovered relativity. New theories only create new effects in borderline cases - high velocities and long distances for relativity, small scales for quantum theories.

We actually know very well where the current theories do not work and new ones will be needed. But no matter what those new theories are, the old ones will still hold true in those areas where they've been thoroughly tested. And you can rely on the fact that this means there will be no superluminal communication. Unless you can somehow construct a universe that allows causality paradoxes.

Re:Looking back in time.

[Abcd1234]

It's not so much that someone is twiddling particle A and someone else is measuring particle B; it's more like someone is making measurements of particle A, and someone else is measuring particle B, and because of entanglement, those measurements are going to correlate some percentage of the time...

Which brings us back to quantum cloning. *If* you could clone a quantum state, particle B could be cloned. Then, if the waveform of particle A is collapsed, one could measure B and all of it's clones, and based on statistics deduce whether or not particle A had been "twiddled" (since >50% of the clones would collapse to the same state, due to the entanglement with A). Unfortunately, the No Cloning theorem (which I also linked to) makes this impossible.

So you're left with a single particle B who's state you measure. But because of good ol' Heisenburg, there's no way to deduce if the state of B after the waveform collapses is due to manipulation of particle A, or simply random.

Re:Looking back in time.

[Abcd1234]

If you don't want to talk to people who have some degree of ignorance

I have absolutely no problem with that. My problem is that, despite providing you with a number of references which should help enlighten you, you persist in your beliefs. You continue to deny everything I'm saying, rather than reading the literature.

To start off, I'm not denying that QE exists. It does. It's been demonstrated. What I'm trying to explain to you is that it cannot be used to send a signal. Now, from the sounds of it, your entire understanding of QM is based on popsci articles (this isn't a slight... this is the case for most people, myself included, to some degree). Unfortunately, these articles are notoriously inaccurate, and typically simplify things to the point of non-sense.

For example, you seem to think that, given two particles A and B which can represent two states, 0 and 1, if Alice measures A, then particle B immediately changes. This is not the case. It works like this: A and B exist in a superposition of states 0 and 1. When Alice measures A, A takes a definite value randomly, either 0 or 1. Later, when Bob measures B, it will take on the same value.

The key here is that Bob must measure B. But there is a problem: there is no way for Bob to tell if the value of B is a result of Alice performing a measurement, thus causing the waveform to collapse, or because Bob's measurement is the one which caused the collapse. Consequently, there is no way to pass information from Alice to Bob instantaneously, as Bob cannot deduce if Alice has measured A.

And this is why I brought up quantum cloning. *If* you could clone particle B multiple times, such that all the clones are entangled with A, then one could communicate as follows: Alice measures A, causing the waveform to collapse. Bob then proceeds to measure B and all the clones. If Alice was the one which caused the waveform to collapse, then Bob would observe the clones as having the same value. However, if Alice did not collapse the waveform, then the clones would each take some state randomly. The problem is that, as per the article, quantum cloning is not possible.

So does that make sense?

Re:Looking back in time.

[Abcd1234]

Personally I think gravity is instantaneous

Oh, well if *you* say so... I take it you're perfectly happy with violating causality, then?

Re:Looking back in time.

[(negative video)]

Yet QE has been demonstrated to sync distant particles faster than lightspeed communication would allow.

Not quite. There are several possibilities. One is that the particles do actually exchange information using particles that travel faster than light. This information creates the statistics when the experiment is repeated several times, but cannot be directly observed or used to transmit tangible information. I consider this unlikely, because it just moves the wrinkle in the rug to the faster-than-light particles, which cannot even be observed.

A second possibility is that the particles have complex internal states that affect their statistics, but which cannot be directly observed. The internal states are synchronized when they are entangled, after which they evolve independently without further communication. For example, the universe could be a cellular automaton and the particles persistent digital excitations; entanglement would be some sort of partial cloning of the digital state. (In terms of the EPR paradox, this is a non-local hidden variable approach.) This theory is also unsatisfying, because nothing suggesting this has been observed, and observing it would probably be damn difficult. On the other hand, it does explain how particles could exhibit randomized behavior that can only be desribed statistically (imagine encrypted messages for which you know neither the algorithm or the key).

A third possibility is that when particles are entangled, they still remain in contact in some geometric sense. For instance, time is stopped in a photon's frame of rest, so its origin and destination are in one sense located at the same point in space. This seems like a reasonable starting point to me: one of the rules of quantum mechanics is that if you add up the likelihood of finding a particle over all points in the universe, you always get exactly 100%. But how do you define a continuous sums-to-100% process over the entire universe, when there's a speed limit? In some sense, a single particle is already pulling an everywhere-at-once trick. Entangling two particles isn't really much of a leap.

Re:Looking back in time.

[vindimy]

Sorry, but you sound like you've built the universe. How can you say that nothing can move faster than the speed of light with such a certainty when we only know something about a billionth of a billionth of a percent about our universe? For example, do you know what's going on in the center of a black hole? None of the theories that we are aware of right now can give answer. What about dark matter? Shape of the universe? The origins of it? The last thing we can be is certain about something as huge as universe when we are so small that we can't even see where it ends.

Re:Looking back in time.

[Goaway]

Don't project your own ignorance onto others. We know a whole lot about the universe, and claiming otherwise is quite frankly rude to those who dedicate their lives to studying it.

Re:Looking back in time.

[vindimy]

No, I wasn't trying to discredit anyone's work, and I think their (scientists') dedication will keep us moving forward. Of course we know a lot more about the universe than we knew not so long ago, but all this knowledge is relative - it's like having a hamster who knows every corner of the box that it lives in, while its goal is to learn about a solar system. I just think that there are some things that the human mind is not equipped for, just like you can't teach calculus to a dog.

Re:Looking back in time.

[The_Wilschon]

Well, fair enough. To put myself at further risk of being overly pedantic, you might have just said that gravity propagates at no more than the speed of light. Then I probably wouldn't have nitpicked at all. I'm glad that you know what you're talking about, but I really am overly picky when it comes to physics, and I hate to think of other people getting the wrong idea from something like that. Sorry.

Re:Looking back in time.

[Tired and Emotional]

Doesn't matter. Its classical - it comes out of the General Relativity equations. You don't need to postulate gravitons for gravity to travel at the speed of light.

Re:Looking back in time.

[pnewhook]

You also aren't even observing the past, you are observing the present - the light waves as they are currently striking your eye. Just because they traveled for a while doesn't mean you are seeing the past. It's like saying if someone visits me from China, I have traveled back in time the 12 hours that it took for them to reach me. In other words, it's total nonsense.

No, you are completely missing the concept.

When you see something you are always seeing the past - what that object looked like when the light left it.

Think of it this way... when you see our sun, you are seeing how it looked 8 minutes ago. If the sun blew up right now (ignoring all the other issues associated with the sun exploding), you wouldn't see the explosion for another 8 minutes even though it already happened.

Re:Looking back in time.

[pnewhook]

No, I understand the concept perfectly. I just don't agree with it.

Actually it is quite clear from your responses that you do not understand.

Yes, but you are still observing the present moment. Just because the light reaches you later doesn't mean you are observing the past.

Actually you are observing light from the past at the present moment. Note the subtle but important difference from what you said. The fact that the light has been altered is irrelevant.

Re:Looking back in time.

[x2A]

Occording to relativity, anything travelling at the speed of light doesn't age, which means that the light doesn't age between it leaving its source and reaching you, which means that it is the same light as the past, so you are observing the past - in the present.

To use your china analogy, it's more like, if someone came from china, bringing a photograph they took before leaving, then when they show it to you, the photograph does show what things were like those 12 (or whatever) hours ago. The photograph itself might be in the present, but it's content - what you're looking at - are of the past. This is the same as looking at light from the past; the light may have reached the present, but we're not looking at the light, we're looking at the image carried in the light, which is from the past. Disagree all you want, you'll find you're in the minority opinion.

Re:Looking back in time.

[dangitman]

Actually it is quite clear from your responses that you do not understand.

Why not? If it's so clear, why don't you point it out? We are always observing the present moment. End of story. Even if the light is from the past, it's still in the present moment that we are perceiving it.

Re:Looking back in time.

[Fyz]

Gravitons or no gravitons, general relativity states that gravity will propagate at the speed of light. (Indirect) measurements of gravitational radiation from (among others) the double pulsar PSR1913+16 indicates this.

Re:Looking back in time.

[locofungus]

However, (and not that I'm not the grandparent poster), I've long asked myself: How do we even know superposition exists? You can't measure it, since doing so will cause the particle to take on a state.

In order words: How do you differentiate between the case where particles A and B exists, with the same state, and the case where A and be are in a superposition, quantum entangled?

As a start, consider a source of entangled particles that sends one to A and one to B.

There are two possible measurements that A and B make, I'll call them % and & and they are conjugate operators - i.e. measuring % destroys all knowledge of & and vice versa.

% has results 0 or 1
& has results + or -

Now the clever bit: A and B set it up so that A takes measurements just before B (e.g. put them 100m apart with the source 49m from A and 51m from B) but their measurements are so close in time that no lightspeed communication can take place between A and B before B has completed the matching measurement to A. (the choice of which measurment to make also has to be left to the last possible instant)

A and B each (independently) make a random choice whether to measure & or % for each particle and record all their results.

Each find that the results are random - 1/2 of the % measurements have 0, 1/2 have 1. Likewise for the & measurements. (assuming both measurements are equiprobable there will be 1/4 for each of the four possible results)

Now they get together and compare their results and find something remarkable: every time that A and B randomly decided to make the same measurement they find that if A got 0, B got 1; if A got +, B got -. (Again assuming both measurements are equiprobable then this would occur 1/2 of the time)

So the particles, despite behaving randomly for both A and B are clearly correlated.

The first guess would be hidden variables - the results of both the possible measurements are 'known' to the particles when they're created - google for Bell's inequality for how this possibility can be eliminated.

The problem with this 'simple' experiment is that in any practical setup there's a lot of noise obscuring the results. It's also necessary for A and B to only decide which measurement to make just before the particle arrives, otherwise there's time for the measuring equipment to communicate - either with the source or with each other. Assuming that our particles are travelling at the speed of light and 100m is about the limit of separation (we're talking about ultra stable controlled laboratory conditions here) we're talking about having equipment where we can change what we want to measure in around 100ns.

Tim.

Re:Looking back in time.

[TigerTim]

I certainly think that you're right about "looking into the past" is a cliche. So maybe this analagy might clear things up: You're at Bristol Temple Meads Station and the 10:52am from London Paddington comes in (it started in London at, say 8:30am). You rush up to the inspector and have a conversation: You: "What's going on in London right now?" Inspector: "Well I can tell you what happened this morning; I had a good breakfast!" You: "But I want to know what's happening now!" Inspector: "I can't help!" The Inspector can't help because his knowledge about where he started is confined as it were, to when he left. He can tell you nothing about London as it is now, nor is it correct to say that his information comes from the present just because you're receiving it now! It is I think, quite incorrect to suggest that you're somehow "seeing the present". This claim defies special relativity because it would imply that the information has travelled instantaneously. If you know any special relativity, you'll probably recognise that the idea of a "present" is not well defined in any case! And what do you mean precisely by "its appearance is altered on the trip, for example by traveling through the Earth's atmosphere". You can get coherent photons that have travelled from precisely this sort of system that will interfere. You need to be rather precise about what you mean.

Re:Looking back in time.

[T1nuz]

The analogy doesn't prove your point. You're saying that looking at a photograph is nothing like looking at the person with your own eyes. That's just because the information your eyes are receiving is constantly being updated. Indeed, alot of information is being lost and distorted, but that is simply because you perceive more information than can be contained in the photo. And even if this was so, the light has to be altered before is reaches your eyes, so that is still in the past.

Re:Looking back in time.

[greylion3]

Because gravity also propagates at the speed of light.
Wrong.
The speed of gravity hasn't been measured yet, so it is still in dispute.
http://wugrav.wustl.edu/people/CMW/SpeedofGravity. html

If you ask me, the speed of gravity is far higher than the speed of light.
Also, black holes are really MECO's:
http://en.wikipedia.org/wiki/Magnetospheric_eterna lly_collapsing_object

Re:Looking back in time.

[kmac06]

Well it works out just fine with mass distorting spacetime through general relativity. But gravitons are a quantum particle, so general relativity can't really describe them.

Re:Looking back in time.

[dkf]

That's (part of) why Quantum Gravity is a hard and unsolved problem...

Re:Looking back in time.

[x2A]

No, you're just being arsy because you think it sounds clever. It doesn't. Just because some of the light might get absorbed by dust/atmosphere between you and the source, does not mean that what gets through is not from the source. The event that cause the photon to be released happened in the past, and you receiving the photon means you know that the event must have happened. The act of intercepting the photon is known as "looking", therefore receiving photons generated in the past is looking at events that occured in the past, thus, you are looking at something in the past. Of cause things will be different if you go right up to it, because the photon spreads out it you view it from further away, and so the amount of receive will obviously be less. And yes, if it passes close to a planet or something, it can squash the beam, but the information is not lost, and it's still the same light. You can drop words like "philosophical" in all you want, but it's just pseudoscience because you don't understand the reality of it. Don't make the mistake of thinking the universe bends because you lack proper understanding of it or what people are doing.

"Once upon a time, the majority believed the Earth was flat"

This is actually much debated. People used to believe that the earth was center, with the sun/moon going around it, but there's huge evidence showing that the idea of everyone (or even most people) believing the world was round is flawed. Evidence includes discovery of coins with king and globes on them (showing people high up believed it to be round, not just some heretic in some village), people realising that for ships to disapear over the horizon must mean there was a curve (otherwise they would keep getting smaller, not disapear). Right back to Eratosthenes, who devised the system of latitude and longitude, and calculated the circumference of the earth around 220BC with an error of around 15% (measuring difference in angles of shadows cast from the sun in Aswan and Alexandria). Early models of the solar system showing the sun/moon going around the earth clearly shows the earth as a ball (makes sense, to believe the sun goes around something implied the something must be round).

Err, I'm getting carried away, was just a little impressed with what people managed to work out 2000+ years ago, distroyed by rumour created by people trying to show "the light" by showing how barbaric and misinformed people in the past were. If only the earth was at the end of the telescope, maybe we could see what really went on.

Re:Looking back in time.

[somersault]

So basically, you're perceiving something that happened quite a while ago. Funnily enough, that is you basically looking back in time, even if you didn't go there. The present state of the sun is not the state that you can currently see, so basically you are looking back in time, even if the light is presently entering your eye. Everyone that knows about the light taking a while to reach us knows that they're not travelling through time, but they also know that they are not watching what is currently happening, hence looking into the past. That's me trying to point it out. What's the point in saying that we are only perceiving it in the present moment, apart from the very good point that there really isn't such a thing as 'time', that we are always in the present and all the theoretical wormhole stuff therefore seems like BS.

Re:Looking back in time.

[RancidBeef]

Bah! You're both right. Just a difference in semantics.

Re:Looking back in time.

[rubberbando]

I wonder what would happen if we placed a rather large mirror far out into space that we could look at via telescope...

Would we see into our own past?

Re:Looking back in time.

[bdonalds]

Oh, well if *you* say so

Dude, it's clearly stated right there in the Bible!

Re:Looking back in time.

[AndersOSU]

Alright, I don't think anyone has it quite right (and there is a very good chance I don't either), but while it is true that the photons you are seeing left the sun eight minutes ago, for all intents and purposes you are still seeing the present when you look at the sun. This is because even if the sun blew up "now" not only is there nothing we could do about it, but the fact that no information could reach us means that it doesn't happen until we can see it happen.

It is all about simultaneity and relative time. To steal (and badly mangle) a vaguely remembered example from my college physics text imagine a cosmic horse race. If you are standing at the betting window all bets will be closed the moment that the information that the race has started reaches the window, not the moment the information reaches the window minus the distance divided by the speed of light (which would require knowledge of future events). The fact that that information reached someone standing closer to the track is irrelevant, because he can't act on it and place a bet before the window closes.

So in summary my understanding is that just because everyone sees the sun blow up at a different time doesn't mean that it isn't blowing up in the present for everyone.

Re:Looking back in time.

[Luyseyal]

The fundamental problem is that the sender cannot specify what state the sender photon goes into (otherwise, the entanglement drops out).

Example:
You define spin up as 1 and spin down as 0. You attempt to set the state to "spin up" to send a 1. Entanglement drops out. Local particle goes spin up, remote particle goes random.

What actually works:
You don't define anything because it's pointless. You gently observe the sender particle. It goes into a random state. A remote observer will observe the same random state.

Not very helpful is it?
-l

Re:Looking back in time.

[Talahaski]

Sure, its possible to see our past. I'm not sure about being able to send a mirror far enough out there. The best chance we have would be to find some way of capturing reflected light and interpreting it. So light leaving the Earth might reach many light years away and then his some large planet with good light reflective attributes, thus bouncing the light back towards us. Granted with the movement of the universe, solar system, and Earth itself, it would be be unlikely that any reflected light from that far away would make its way back to Earth's current or future location.

Re:Looking back in time.

[p3d0]

You also aren't even observing the past, you are observing the present - the light waves as they are currently striking your eye.

This is not the way the rest of us use the term "see". When light waves reach my eye after bouncing off a dog, I say that I see the dog, not that I see the light waves. Same with a star: when light reaches my eye after being emitted from a star, I say that I'm seeing the star.

Since the light left the star N years ago, I'm seeing the star the way it would have looked to a local observer N years ago. This part is not a matter of opinion or of semantics. If you accept that the light has traveled for N years, then it is a fact.

Re:Looking back in time.

[beckerist]

Considering there ARE mirrors on the moon, and the light takes approximately 2.5 seconds round-trip, you ARE seeing the same photons you'd sent 2.5 seconds ago. So to answer your question: yes. In reality, you would never receive an "image" back, as with every particle between here and there (ie: our atmosphere) will reflect, refract, and otherwise distort the "image" (read: combination and organization of sent photons), making it return as a set of seemingly random photons.

...of course we COULD get into the math behind deciphering Gravitational Lenses, but yeah, maybe another time :-).

Re:Looking back in time.

[beckerist]

Not exactly. Neither are necessarily "right" as it's entirely due to perception. Then we get into subjective metaphysics, and I'm not touching that. I recommend reading the differences between absolutism and relationalism.

Re:Looking back in time.

[pnewhook]

Ok, lets do this another way. Think of a lightning strike - because of the finite speed of light, when you see the flash the lightning has already occured so you are seeing something that has already happened - the past. But accorning to your logic, you are seeing the present, not the past, since you are perceiving it in the hear and now.

Now, several seconds later you hear the thunder. That sound is also from the past, from the same exact event in time as the flash of light. But according to your logic that sound is happening now. Therefore the only conclusion you can make with your logic is that the sound and light are two separate events since you perceived them at two different times.

Re:Looking back in time.

[ebatsky]

i have 0 clue about quantum mechanics etc (comp sci major).

however, would this be possible:

bob tells alice that he will send a signal to her as follows:

at exactly 1 hours, 23 minutes, 33 seconds, 50 milliseconds... (whatever time precision you want to use) bob will change the state of particle A.
at 1 hours, 23 minutes, 34 seconds and 50 milliseconds... bob will change the state of particle B.
then continue for as many particles as you wish.

if all these changes take place and assuming relatively perfectly synchronized clocks, would that not mean that there is a high probability that bob did, indeed, send a message? also increasing the number of particles and the precision of time would increase the degree of certainty, as far as i can see anyway.

again all i know about quantum physics is popular literature so i have no idea if this is anywhere near the realm of possibility, but im simply curious why it wouldnt (or would) be.

Re:Looking back in time.

[Abcd1234]

It's an interesting idea, but the problem is that when Bob makes his observations, the values the particles take are entirely random. Remember, Bob doesn't get to select the values. It is simply that whatever values his particles take will be reflected on the other entangled particle in the pair when an observation on that particle is performed.

*However*, what this *is* useful for is generating a one-time pad. Suppose you have Alice and Bob wishing to communication 100% securely. You take a source of, say, entangled photons and send them to Alice and Bob. Alice then observes the particle at time t, generating some random value x. Bob, at time t' > t then performs an observation on his particle, and gets the same random value x. Meanwhile, Alice takes a bit from the message she wishes to encrypt, XOR's it with the value x, and sends it to Bob, who then performs the same operation. Voila! Bob has the message. And because of the observer effect and the no-cloning theorem, there is no way for Eve to gain access to the pad.

Note, there was no FTL communication, here. The information to be communicated is in the message itself, which can only be transmitted in a classical sense, limited to the speed of light. What QE allows is for two individuals to have a synchronized source of random data.

Sounds familiar...

[__aaclcg7560]

In galaxy far, far away...

Re:Sounds familiar...

[ArcherB]

More accurate to say:
A Long Time Ago in a Galaxy Far, Far Away...

Close though.

Re:Sounds familiar...

[__aaclcg7560]

I had a catastrophic brain fart trying to get my mind wrapped around the idea of a billion light years. Still trying to recover from the idea that Andromeda is a million light years wide. When you thought the cosmos is a small place, it's getting larger.

Re:Sounds familiar...

[doti]

I had a catastrophic brain fart trying to get my mind wrapped around the idea of a billion light years. Douglas Adams prediced that:

Space," it says, "is big. Really big. You just won't believe how vastly hugely mindboggingly big it is. I mean you may think it's a long way down the road to the chemist, but that's just peanuts to space.

What is this light speed thingie?

[Sadko]

Considering this is /., the article quote seems a bit redundant -Cheers,

it travels as fast as it travels

[User 956]

That's interesting, he explains, because given that light travels at a finite speed -- 300,000 km a second

...in a vacuum. When not in a vacuum, light can travel at a fraction of the speed of light.

Re:it travels as fast as it travels

[Capt'n Hector]

gosh, to bad there's no vacuum out there, especially in space...

Re:it travels as fast as it travels

[User 956]

gosh, to bad there's no vacuum out there, especially in space...

For a complete vacuum, it certainly has a lot of stuff in it to look at.

Re:it travels as fast as it travels

[symbolset]

So... what is the speed of light in, say, lead? and...

who's got a billion light years long spool of fiber optic cable anyway?

Re:it travels as fast as it travels

[Dunbal]

For a complete vacuum, it certainly has a lot of stuff in it to look at.

      Someone forgot to clean out the filter? My vacuum filter always gets full of gunk after a while...

Re:it travels as fast as it travels

[heinousjay]

I always assumed that whatever speed light traveled at was the speed of light.

Re:it travels as fast as it travels

[honkycat]

It's pretty darn close to a perfect vacuum... according to Wikipedia (and my recollection), the average density of the universe is less than 1 atom per cubic meter. That includes all the pretty things out there to look at...

Re:it travels as fast as it travels

[kfg]

...in a vacuum. When not in a vacuum, light can travel at a fraction of the speed of light.

Well no, not exactly. When not in a vacuum it takes rest stops which reduce its average speed, but when not taking rest stops it travels at the designated finite speed; because that's the only speed at which light can travel. There was this Maxwell guy who 'splained it.

You know about the pony express? Well, they had posts along the way to change horses. Let's say, for the sake of simplicity, that these posts were 15 miles apart and that the horses traveled at a finite speed of 15 miles per hour. When the horse is moving it is always going 15 miles per hour, but the average speed of the horses over a full day is 13 miles per hour because of the time it takes for the rider to change them on an hourly basis.

Light is like the Pony Express, only without the horses, which wouldn't be like the Pony Express at all, would it? That would just be some guy taking a walk.

Nevermind.

KFG

Re:it travels as fast as it travels

[gstoddart]

...in a vacuum. When not in a vacuum, light can travel at a fraction of the speed of light.

They're in luck. This light travelled through space ... and therefore, a vacuum!!

Oh those wacky astronomers for actually using c correctly. :-P

Cheers

Re:it travels as fast as it travels

[kfg]

Well now I'm all confused about whether I'm a wave, a particle, or a horse, so I'm just going to cheese out and post a reference:

http://www.glenbrook.k12.il.us/gbssci/phys/class/r efrn/u14l1c.html

KFG

Re:it travels as fast as it travels

[kitsunewarlock]

"My secretary sent me light-speed and I didn't get it for 3 days. That's because the vacuum is clogged."

Re:it travels as fast as it travels

[jgoemat]

Even space isn't a perfect vacuum. There are a few hydrogen atoms per 10 cm^3 even in deep intergalactic space.

Re:it travels as fast as it travels

[Arthur Dent '99]

Perhaps the universe uses a Dyson vacuum, so there are no filters to replace! Then, perhaps, would a Dyson sphere simply be a huge dust bunny formed by centrifugal particle separation? :-)

Re:it travels as fast as it travels

[AusIV]

What do you mean by "a fraction?" That's an incredibly vague term that tells absolutely nothing about how fast the light is traveling. 999/1000 is a fraction, as is 1/1000, yet there's a lot of variance in between (especially when dealing with the speed of light.

Sorry, it just bugs me when people use the word "fraction" that way.

Re:it travels as fast as it travels

[IngramJames]

...in a vacuum. When not in a vacuum, light can travel at a fraction of the speed of light.

When not in a vacuum, light can travel at a fraction of the speed of light in a vacuum.

Thank you, fans, I shall collect my analanity award later.

Re:it travels as fast as it travels

[IngramJames]

What do you mean by "a fraction?" That's an incredibly vague term that tells absolutely nothing about how fast the light is traveling. 999/1000 is a fraction, as is 1/1000, yet there's a lot of variance in between (especially when dealing with the speed of light.

Sorry, it just bugs me when people use the word "fraction" that way.

Parent poster was correct, in this case. The fraction of c which light will travel at through air is *different* to the fraction of c that light will travel through water, mist, heavy cloud, or hamsters. Without knowing the medium through which light is travelling, "a fraction" is an accurate description; it will never *exceed* c, but you cannot tell how how fast it *will* be going.

Re:it travels as fast as it travels

[Samah]

Is that average taken from the bounded universe or from the space available?
Given that the universe is still expanding (for the time being), the bounding box (sphere?) would be increasing. Since matter/energy cannot be created nor destroyed (screw you, creationists) we have the following formula, where m represents the number of whole atoms in the universe (ignoring subparticles for now), d represents the amount of 3d space in metres^3 currently used by the universe's bounding box/sphere/whatever, a represents the density of the universe in particles per cubic metre and t represents light years since the big bang:
a = m / d

If we assume that the universe was originally a point entity of 0 size and the universe will eventually stop expanding and contract for the big crunch, we can plot a graph of time by density with 2 vertical asymptotes at t = 0 and t = (life of the universe), and a horizontal asymptote at a = 0.

This means that when the universe gets middle-aged, two things will happen:
-- the density of the universe will reach a trough approaching 0 (the universe will make itself scarce by going down the pub on Fridays),
-- the universe will begin contracting again, increasing the density once more (the universe will stay at home more incase the wife finds out it's been giving one-liners to the hot blondes at said pub).

only 1 billion ly?

[Gospodin]

I RTFA, but it didn't discuss why 1 billion ly was such a big deal. Don't we look at stars (albeit clustered into galaxies) that are much farther away than that all the time? Is this a record for looking at individual stars?

Re:only 1 billion ly?

[Harmonious Botch]

"I RTFA, but it didn't discuss why 1 billion ly was such a big deal. "

Didnt seem like a big deal to me either. Ok, you can see stuff that is older, but until you quantify what you are seeing, it's not hard news. Now if they find different composition of stars, or different than expected output, then that is news.

Re:only 1 billion ly?

[MindStalker]

Yea the visible universe is some 46 billions light years. They are referring to detecting individual starts a billion light years away whereby normally you would only see a galaxy with non identifiable individuals stars at such a distance.

Re:only 1 billion ly?

[somepunk]

Yeah, the summary is bogus (surprise, surprise). The big news is that this is the furthest cluster of stars yet observed, a confusion not encountered in TFA.

Re:only 1 billion ly?

[Ignorant Aardvark]

Might want to research some physical cosmology ... the universe has expanded faster than the speed of light.

Re:only 1 billion ly?

[maird]

That is something I just don't understand. In simple terms, I believe the universe grew from a point source. If we take your comment at face value (I have no knowledge that permits me not to) then, also in simple terms, 46 billion light years worth of distance are visible (presumably 23 in any direction). If we are looking "back in time" to the time of emission when observing light from a remote source then, if nothing can travel faster than the speed of light, how can the age of the universe be estimated at 13 billion years or so? Surely, no thing in it could be further away from any other thing in it than "age of the universe" light years. To do so would require two objects to have a relative speed exceeding the speed of light I believe. IOW, if the universe is 13 billion years old then how can I see something 23 billion light years away, it's light would have to have been emitted before the universe existed which, in my crude understanding, is meaningless. I suppose I can almost believe the idea that the observable universe cannot exceed the age of the universe light years in any direction. Even that gives me problems but this point has worried me for years, I'd really be interested in an authoritative source.

Re:only 1 billion ly?

[maird]

I never knew what question to ask before reading this branch of the discussion. Whether or not it is accurate is beyond me but, I think I can feel good about this: http://en.wikipedia.org/wiki/Expansion_of_the_univ erse

Re:only 1 billion ly?

[shawnce]

From Observable universe:

For example, the cosmic microwave background radiation that we see right now was emitted about 13.7 billion years ago by matter that has, in the intervening time, condensed into galaxies. Those galaxies are now about 46 billion light-years from us, but at the time the light was emitted, that matter was only about 40 million light-years away from the matter that would eventually become the Earth. See comoving coordinates.

Re:only 1 billion ly?

[MindStalker]

star sorry that T sneaked in there somehow.

Re:only 1 billion ly?

[Nimey]

Maybe. One model uses inflation in the moments after the Big Bang to explain certain things. That's a model. Scientists may think it's a pretty good one, but it's not the actual item and could be completely wrong.

Re:only 1 billion ly?

[Bucko]

Maird,
It's not quite right to think that the universe "grew from a point source." There was nothing (no physical matter or information) that went from point A to point B faster than light. Think of it like the surface of a pond freezing out. It can do so everywhere at once, with out something moving from one side of the pond to the other. Remember that Einstein's famous limit on the speed at which something can travel applies only to stuff that has mass (=energy) or carries information. The line you draw with your mind from the tip of your finger to the edge of the universe can go from one side of the universe to the other as quickly as you can swing your arm, but the end point of that line is not violating relativity. Stuff is moving through space, and space itself is expanding independent of that movement. Those are two separate things.

Re:only 1 billion ly?

[coastwalker]

I'm just making a guess here but it goes something like

we get the age and size from the frequency of the microwave background radiation.

The background is measured at 3.5 kelvin (degrees above absolute zero) which relates to the microwave frequency by wiens law (sorry very rusty on the details, frequency of the light given off by an object at a certain temperature is defined by the laws of thermodynamics, the hotter it is the shorter the wavelength).

when the big bang occurred particle physics can give a value for the temperature of the universe.

When you look at the oldest light it came from the glow of the universe at that temperature - and it started out with a wavelength related to that temperature.

That oldest light has been stretched by the red shift by the expansion rate of the universe and is now at a very long wavelength which we see as the microwave background radiation in every direction in space.

we can measure the rate of expansion of the universe by looking at standard candles (supernova which pop with the same brightness - so we know how far away they are by their brightness) and measure their red shift. So we know how much red shift occurs for a certain distance.

so if we look at how much red shift the oldest light has suffered from its original high frequency we can work out how far away it comes from - or how old it is - because it has traveled to us at the speed of light 3*10exp8 m/s.

The figure that comes out of this pile of logic is apparently around 13 billion years. Maybe someone can verify or correct that this is the logical linkage used in the calculation.

Re:only 1 billion ly?

[Anonymous Coward]

This has nothing to do with inflation. Units for the expansion of the universe are m/(m*s), or just 1/s. Units for the speed of light are m/s. So you can't compare the two. What you can ask is whether there exist two points of the universe that are expanding from each other faster than c, and the answer is probably yes, even today (not just moments after the Big Bang).

Wait...

[Draconix]

Ric Romero is submitting articles to Slashdot now?

paraphrasing Douglas Adams

[Ubergrendle]

Yet more evidenence that mankind cannot truly comprehend the vastness of space. Travelling 1 billion years at the fastest possible speed known to science doesn't even get us to the edge of the universe.

I remember a highschool experience. A teacher had a record, put it on the table. "Ok, see the hole in the middle? That's the sun. Track 1 is approximately where the earth is located. The outer edge might be pluto's orbit. Heliopause? That's probably in the teacher's parking lot. Ok, so the next closest galaxy is Alpha Centauri, so that is approximately...well, Hamilton." (We were in Toronto, Hamilton is 100km+ away).

Re:paraphrasing Douglas Adams

[Neeth]

closest galaxy? You mean the closest star. I wonder where, on your scale, the closest galaxy would be. Maybe the sun?

Re:paraphrasing Douglas Adams

[Dunbal]

Travelling 1 billion years at the fastest possible speed known to science doesn't even get us to the edge of the universe.

      Ahh, but the beauty of it is that if you _DID_ travel at or near the speed of light, one billion years would not seem like such a long time at all - certainly doable within a lifetime! So if you asked those photons how old they thought they were, you'd be surprised at the answer... so the photons aren't really that old at all! Confused yet?

Re:paraphrasing Douglas Adams

[Rob T Firefly]

You kids and your fancy record albums! In my day, it was explained to me that the Sun was the hole in the middle of a gramophone cylinder, and the Earth was the trunk in my room at the orphanage in which I kept my knickerbockers, and the farthest planet Neptune would probably be down by the paper mills where all us kids would look for work. Now get off my lawn!

Re:paraphrasing Douglas Adams

[vindimy]

Whoever didn't get this, give yourself a hand and read Wiki's Time Dilation topic. Save yourself some embarrassment from typing nonsense questions and arguing.

Re:paraphrasing Douglas Adams

[silentounce]

That's a rather humancentric way of looking at it. Do photons really "age"?

Re:paraphrasing Douglas Adams

[vindimy]

Specifically, from Wiki:

Time dilation would make it possible for passengers in a fast moving vehicle to travel further into the future while aging very little, in that their great speed retards the rate of passage of onboard time. That is, the ship's clock (and according to relativity, any human travelling with it) shows less elapsed time than stationary clocks. For sufficiently high speeds the effect is dramatic. For example, one year of travel might correspond to ten years at home. Indeed, a constant 1 g acceleration would permit humans to circumnavigate the known universe (with a radius of some 13.7 billion light years) in one human lifetime. The space-travellers could return to earth billions of years in the future (provided the Universe hadn't collapsed and our solar system was still around, of course)...

Re:paraphrasing Douglas Adams

[Kjella]

Ahh, but the beauty of it is that if you _DID_ travel at or near the speed of light, one billion years would not seem like such a long time at all - certainly doable within a lifetime! So if you asked those photons how old they thought they were, you'd be surprised at the answer... so the photons aren't really that old at all! Confused yet?

Not until you got back... Most people feel lost after a few decades, after a few billion years I bet your first two questions would be "Where's earth?" and "Where's the humans?" and I doubt you'd recognize either even if they were right where you left them. Also, massless waves are a wierd bunch, even if they go through glass or water slowing them down to less than c I doubt they age in any meaningful sense.

Re:paraphrasing Douglas Adams

[smoker2]

A teacher had a record, put it on the table. "Ok, see the hole in the middle? That's the sun. Track 1 is approximately where the earth is located. The outer edge might be pluto's orbit.

So your teacher used to play his records backwards ? Any cryptic messages come through ?
(hint - track one starts at the outside edge)

Re:paraphrasing Douglas Adams

[wanerious]

Nope. If you travel at the speed of light, then nothing ever happens.

Re:paraphrasing Douglas Adams

[Tyler Durden]

The best page I ever saw describing what near c travel would be like is The Relativistic Rocket. It details what would happen if one were to travel for extended periods of time in a ship with constant acceleration. (Preferrably at 1g).

It provides equations giving the velocity and distance travelled by the ship in terms of time as viewed from where the rocket was launched and within the rocket itself. That and the explanations are definitely worth a read.

Re:paraphrasing Douglas Adams

[CrimsonAvenger]

I remember a highschool experience. A teacher had a record, put it on the table. "Ok, see the hole in the middle? That's the sun. Track 1 is approximately where the earth is located. The outer edge might be pluto's orbit. Heliopause? That's probably in the teacher's parking lot. Ok, so the next closest galaxy is Alpha Centauri, so that is approximately...well, Hamilton." (We were in Toronto, Hamilton is 100km+ away).

Hmm, your teacher scalig is a bit off, eh? Hole in record is about 1/4". If that represents the diameter of the sun (about 1.4 Gm), then the Earth's orbit is about 27 inches away from the hole in the middle. Pluto's orbit is about 80 feet away. Alpha Centauri (which is certainly the nearest star, but isn't a galaxy at all, much less the nearest one) is about 120 miles away, so nearly twice as far as Hamilton.

No comment about the Heliopause, since I don't know how far out your teachers' parking lot is. But it isn't so far beyond Pluto as is implied by this example. Maybe three times as far out as Pluto.

Re:paraphrasing Douglas Adams

[Ubergrendle]

doh! you're right. i meant solar system.

and you're right the next closest galaxy probably IS the sun...

Re:paraphrasing Douglas Adams

[HappyEngineer]

But photons only travel at c when travelling in a vacuum. Do they "experience" time when they travel through air at a speed less than c? Does this question even make sense? Photons don't have a persistent state that can change over time, so there's no way to tell how old one is.

Re:paraphrasing Douglas Adams

[wanerious]

Well, I was being a little flippant. In a medium, photons travel at c between interactions with the electrons in the medium, so the average speed of photons through a medium is weighted down by these "collisions". Since they're bosons and indistinguishable, there's really no way to tell one that has been absorbed and emitted from one that has had no interactions.

Re:paraphrasing Douglas Adams

[Coucho]

so the next closest galaxy is Alpha Centauri I thought Alpha Centauri was a star system? IIRC the closest galaxy to the Milky Way is Andromeda.

Re:paraphrasing Douglas Adams

[Anonymous Coward]

Bah, you kids and your heliocentric model of the solar system! Back in my day, the Sun rotated around the Earth and the stars were simply holes in a table cloth, and that's the way we liked it! And if you said otherwise you were labeled a witch and burned at the stake...both ways! Now get off *my* lawn!

Re:paraphrasing Douglas Adams

[hjo3]

>> I wonder where, on your scale, the closest galaxy would be. Maybe the sun?

Assuming it was a 12" record, Andromeda (the nearest galaxy) would be about 4.1 AU (~381 million miles) away. This is roughly the distance from Earth's orbit to Jupiter's orbit, or about four times the distance between Earth and the sun.

Re:paraphrasing Douglas Adams

[dangitman]

Ok, see the hole in the middle? That's the sun. Track 1 is approximately where the earth is located. The outer edge might be pluto's orbit.

That doesn't make any sense. On a record, track 1 is at the outer edge of the disc, not closest to the hole.

Re:paraphrasing Douglas Adams

[hjo3]

Woops! Before anyone corrects me, Andromeda is the nearest spiral galaxy. There are some closer galaxies, but they're irregular, dwarf, or elliptical. Andromeda's the closest thing to us that's on par with the Milky Way in terms of size.

Re:paraphrasing Douglas Adams

[lawpoop]

Neptune?! Why, in my day, we only had Uranus!

Re:paraphrasing Douglas Adams

[TexVex]

If a photon is absorbed by an electron and re-emitted, is it really the same photon?

If you say yes, then what about when one photon is absorbed and two are subsequently emitted?

Re:paraphrasing Douglas Adams

[tm2b]

Bah.

In my day, Pluto was a full planet.

Re:paraphrasing Douglas Adams

[1u3hr]

he best page I ever saw describing what near c travel would be like

And the best fictional treatment of this is Poul Anderson's Tau Zero.

Re:paraphrasing Douglas Adams

[PadainFain]

Indeed. And as the great Carl Sagan pointed out in Cosmos it would only take a device accelerating at a constant 1g to be able to travel to and return from the Andromeda Galaxy in a human lifetime. Only problem... about 3 million years would have passed on earth.

A quick back of an envelope calculation shows that at 1g you would reach relativistic speeds inside 4 years with that acceleration. Of course you have to decelerate for half the journey. So 8 years 'wasted' but the rest of the journey experiences significant time dilation. And the longer the journey the more extreme the time dilation. Travelling to the centre of the galaxy and back would take a relatively huge one-third of the time of the journey to Andromeda for the voyager, but a mere 1% of the time would have passed back on Earth.

*All numbers subject to change due to memory loss or changes to the rules of Physics.

Re:paraphrasing Douglas Adams

[coastwalker]

Its not quite that simple though is it? Because to maintain your 1 g acceleration up near relativistic speeds the ship would start accumulating mass in an exponential fashion requiring unbelievable quantities of energy to maintain the acceleration.

So you would probably only get to 50% light speed before any conceivable stock of propulsion energy would become exhausted. you would get far less time dilation and maybe you would need significantly more than a single lifetime to get to Andromeda.

Re:paraphrasing Douglas Adams

[PadainFain]

It's a thought experiment but it's not totally inconceivable. There were plans for spacecraft not so far removed from this idea drawn up in the 70's. Technically they're possible but practically they're too expensive!

Anyway, the point is that the asymptotic approach to the speed of light with a constant acceleration, or even with a constant force, produces results that boggle the mind.

The Lorentz factor at 2c/3 is only 1.34, at 99.97c/100 it's ~40. At 99.9997c/100 it's ~400. Not as large as you'd think for being within 0.0003% of c.

And think... to go from 99.9997% of c to 99.9999997% only requires an increase in velocity of 1000m/s, 100 seconds under 1g at rest mass. Through this velocity your Lorentz factor mean is ~7000, so it'd take a mere 700000 seconds. A mere 8 days or so, during which nearly a thousand years passes on earth.

Re:paraphrasing Douglas Adams

[PadainFain]

Sorry, Missed a factor of ten. It'd be about 80 days on the craft, 10,000 years on earth.

Re:paraphrasing Douglas Adams

[wanerious]

Well, of course they're indistinguishable only if the emitted radiation is the same wavelength as the absorbed. If two are emitted, then they must have different energies than the original.

Can you say that again?

[chill]

I don't get the whole "back in time" thing. Saying it 3 different ways in a 3 sentence blurb isn't quite enough. Is this, like, before the Great Flood? :-)

Re:Can you say that again?

[gstoddart]

I don't get the whole "back in time" thing. Saying it 3 different ways in a 3 sentence blurb isn't quite enough. Is this, like, before the Great Flood? :-)

Assuming you're not being flippant ..... (in which case I'm being pointlessly pedantic)

Since the light took 1 billion years to reach us, it's, well, "old light" that occured in the past. We're not seeing those objects as they exist today, we're seeing them as they existed 1 billion years ago. Hence, we're looking into the past. We have no idea what they look like today -- they could have all gone nova 500,000,000 years ago. But, we won't know for another 500,000,000 years that it has happened.

And, yeah, way before the great flood. ;-)

Cheers

Age

[Dr. Cody]

In other words, these pictures are one billion years, two months old.

Re:Age

[dangitman]

Daddy, I'm 1 billion and one sixth! Can I finally get a pony now?

Surprisingly enough

[darjen]

A speck of light created a billion years ago looks exactly the same as it does today. Astonishing!

Re:Surprisingly enough

[vindimy]

The light has traveled through an unimaginable distance, and you expect it to look the same? Where did you get this silly idea anyway? Were you there 1bln years away and see this light yourself so you have something to compare to? Man, only on Slashdot I can find... Oh wait.

Re:If only there was a galaxy sized mirror near it

[LiquidCoooled]

No you missed the point.

6000 years is about the time anything lasts for.
It just so happens that there are LOTS of things in the universe that were in their ~6000 year window for us to see.
In another 6000 years the entire universe will have changed beyond our imagination.

Re:Does it count...

[Anonymous Coward]

That's like asking "Is it one billion light years from New York or one billion light years from Chicago?"

Is that really the farthest?

[PurifyYourMind]

I know, the article probably only refers to visible light, but note that we've detected things as far away as 12 billion light years: http://hypertextbook.com/facts/1998/JiYoungLee.sht ml http://en.wikipedia.org/wiki/Quasars

Re:Is that really the farthest?

[Abcd1234]

No, they mean the largest individual star cluster. We've imaged galaxies and quasars *much* farther out, but individual clusters of stars? That's much more difficult.

Re:Is that really the farthest?

[pln2bz]

Quasars are only really far away so long as you ignore the research of Halton Arp, like the rest of astronomy does these days. Arp has imaged quasars that are either connected to or in front of spiral galaxies with much lower redshifts. Their redshifts appear to have non-cosmological components that change in discrete quantized amounts as the quasars move away from their parent galaxies. It was previously argued that his statistics were flawed, but a study has come out recently that supports the correlation between quasars and spiral galaxies. Then, astronomers released a study declaring that the redshifts were not in fact quantized. But in fact, Arp was arguing that there is an inherent component of redshift that is quantized -- not the raw measured value. The desire to discredit Arp has always superseded the desire to maintain objectivity in doing so ...

NGC7603:
http://www.thunderbolts.info/tpod/2005/arch05/0502 11thirtyyears.htm

NGC7319:
http://www.thunderbolts.info/tpod/2005/arch05/0506 10arptest.htm

Quasar as Proto-Galaxies:
http://www.thunderbolts.info/tpod/2005/arch05/0501 06universe-arp.htm

The Fingers of God:
http://www.thunderbolts.info/tpod/2004/arch/041018 fingers-god.htm

And of course, Seeing Red by Halton Arp.

Re:If only there was a galaxy sized mirror near it

[Dunbal]

God only made the EARTH 6000 years ago

      No. It was the Flying Spaghetti Monster, not God. Ask the Midgit, he knows.

1 billion light years?

[snowleopard10101]

Sometimes I think they are just pulling those numbers out of their behinds. Is there any solid evidence to prove it? I know they probably use parallax for measurement. But further away the star is from earth less apparent is the shift in position, which means lesser accuracy of determining the distance from earth.

Re:1 billion light years?

[greenrom]

This is a really good question. How do they know the distance? I don't think parallax would work. I would think the difference in angles would be way too small to measure for something 1 billion light years away. Maybe they estimate the distance based on how bright the light is with an assumption about the light output from the star??? Can someone who knows something about astronomy can explain where that 1 billion number comes from?

Re:1 billion light years?

[wanerious]

For galaxies out to about 100 million light years, we can use a well-known relation between the pulsations of bright stars and their luminosities to get a pretty accurate distance. Beyond that, the simplest measure is the cosmological redshift of the light. If the redshift is, say, 10%, then we use the Hubble relation (speed / Hubble constant = distance), where (speed = redshift * speed of light) to get an estimate. We can then independently calibrate this with Type 1a supernovae, which all go off with roughly the same brightness. This is only really useful for smaller redshifts and distances, since asking for the distance of an object with a significant redshift is sort of ambiguous. Do you mean how far is it "now"? How far away was it when it emitted the radiation? But the above is the simplest answer to your question.

Re:1 billion light years?

[exp(pi*sqrt(163))]

Parallax? Dude! Are you crazy? I think there should be a rule on /. Anyone who's going to talk about figures should at least do an order of magnitude calculation on their calculator first. In fact, forget order of magnitude, just order of magnitude of the order of magnitude should be enough to tell you that using parallax to measure the distance of something 10^9 light years away is completely insane. You don't even need a calculator. google will tell you the parallax angle we might get from viewing this cluster from opposite sides of the Earth's orbit.

Re:1 billion light years?

[drpimp]

Agreed. And apparently also light properties have not changed in 1 billion years either, which is amazing to me considering almost everything as we know it exists in some sort of cycle of change/evolution. What's even more particular to me is the fact that we can see 1 billion years ago from some far off star, now as most may see this as some kind of insight to what this star was like so long ago, I for one could only hope to see these far off places in the current time we are in. Unfortunately I don't see this happening, at least with the current technology, guess we can wait 1 billion years to see.

Re:1 billion light years?

[wanerious]

Sure, but those who know the word "Cepheid" probably also know what they're used for. Just thought it would rock to be a little descriptive.

Re:1 billion light years?

[Artifakt]

There is a class of variable brightness star called a Cepheid, because the first example of the class was Delta Cephei.
The pulse rate of these stars is very tightly correlated with their absolute luminosity. A three-day period Cepheid has an absolute luminosity about 800 times the Sun. A thirty-day period Cepheid is about 10,000 times as bright as the Sun. The scale has been calibrated much more precisely than those approximations, using nearby Cepheid stars, where the distance can be determined accurately from parallax observations.
      Minor variations in rate are closely connected to certain metallic ions found in these stars in various proportions, and this can easily be determined as well for new Cepheids, by spectroscope. True Cepheids are population 1 stars, but there is also a related type, called either Type 2 Cepheids or W Virginis variables. These are the older, population 2 versions of the same phenominon. At first, the mix of types 1 and 2 made distance estimate figures rather blurry for distant galaxies, but once it was recognized that they could be divided into the two types, not only did type 1 Cepheids give us some very accurate estimates, but type 2 can be used to get an independant estimate and so check the first one.
        All Cepheids are tremendously bright, and can be picked out individually at distances enormously greater than can a sun sized star. The time for a brightness cycle is long enough that a lot of detailed measurements are possible, but short enough that it will repeat many times in a single researcher's working lifetime, making them ideal in many ways.

Re:I RTFA and I find really F*ed

[spaceyhackerlady]

3)More seriouly "It's too early to say what those differences are, Richer said, but he expects there will be several -- colour among them. That's because the older a star gets, the redder it gets, he says. Younger stars are bluer." This is obviouly the colors shift of the duppler effect, and have nothing to do with the age of the star but the speed relativly with us !

The raw imagery will indeed be red-shifted. That is, after all, how they know how far away the stars are. Hubble Constant and all that.

Since they know the red shift, they can easily prepare a true representation of the colours. Obviously.

...laura

I can just see it

[rucs_hack]

Astronomer 1: How far away is it?
Astronomer 2: In light years? It's OVER 9000!!!!!

wow. remedial time travel

[searchr]

Oh.my.god. Using those figures, according to my calculations, it takes the light from the sun about eight minutes to reach Earth. That means, we aren't seeing the Sun NOW, we're seeing the sun eight minutes in the PAST. So everything we're seeing, everything with the Sun's light on it, is actually touching the past! I'm.. I'm touching the PAST. Looking through TIME.

these are really good brownies.

Re:wow. remedial time travel

[noidentity]

OMG, that means that the sun might have exploded or burned out already, and we won't know for EIGHT MINUTES!!! Remember the opening for Terminator? That could be about to happen in 8 minutes!

factoring spacetime is silly

[Anonymous Coward]

The whole notion of factoring time out of spacetime for special treatement is silly. Other than the fact the metric is a bit odd, thinking in terms of a unified spacetime is much easier. The idea of "sometime else" is just as good as "somwhere else" -- it's the whole fact that the English language is stupidly constructed and people say "some other time" that re-inforces the separation. All you really know as an observer is "local and now" -- i.e. your spacetime point. Claiming the images are very old is non-sensical. What reason do we have to assume there is an underlying universal local clock? Other than it seems to work locally we don't really know anything.

1bil lightyears is too far for me to understand

[fuo]

how many football fields is that?

Re:1bil lightyears is too far for me to understand

[Apocalypse111]

About 1.03461597 × 10^23 football fields, assuming a 100 yard field.
Also equal to 4.70279985 × 10^22 furlongs.
Also equal to 6.32396717 × 10^13 Astronomical Units.
Also equal to 9.31154371 × 10^25 hands.

Any other peculiar units of measure you'd like translations into? Google calculator is really good at this stuff.

Re:1bil lightyears is too far for me to understand

[twifosp]

A football field is 300 yards.

There are 1093.6 yards in a kilometer.

There are 3.654 football fields in a kilometer.
A light year is ~ 9,460,730,472,580.80 kilometers.
There are 2,595,267,579,293.56 football fields in a light year.
There are 2.59527E+21 or 2,595,267,579,293,560,000,000 football fields in a billion lightyears.

Other imperial measurments you might find usefull:
Dime widths to the lightyear: 38,448,408.68
Buicks to the lightyear: 48,060,510,849.73
Hamsters to the lightyear: 961,210,216.99
Goldfish to the lightyear: 120,151,277.12
Obese Americans (Average of obese waist size) to the lightyear: 11,053,917,495.44
'Your Momma's so fat' to the lightyear: 6

Re:1bil lightyears is too far for me to understand

[krunoce]

If you mean just the playing field (100 yards) then it's approximately 1.03461597 × 10^23 yards.

"^" indicates "to the power of".

Re:1bil lightyears is too far for me to understand

[Loconut1389]

What type of football do you play?

Re:1bil lightyears is too far for me to understand

[valkraider]

How many VW bugs could you line up? We all know the only two constant forms of measurement in the USA are VW Bugs (classic) and football fields (American). Oh, and Rhode Island - when you are measuring asteroids or ice shelfs...

Re:1bil lightyears is too far for me to understand

[CrimsonAvenger]

A football field is 300 yards.

I had no idea soccer fields were so large. American Rules Football only uses a 100 yard field.

Re:1bil lightyears is too far for me to understand

[zesty42]

300 "ft" in a football field. No big deal, happens to the best of us.

Re:1bil lightyears is too far for me to understand

[dapsychous]

Do you live near a nuclear power plant? If you can fit 48 billion Buicks, but only 961 million hamsters, you have some hamsters about 50 times the size of a Buick. That's a BIG ASS hamster.

Re:1bil lightyears is too far for me to understand

[Cstryon]

That's rediculous! My mom is about 4.

Re:If only there was a galaxy sized mirror near it

[vindimy]

Is "EARTH 6000" some kind of a new model of Earth? And ours is what, 5000 beta? And I wonder why didn't we notice God making it only years ago.

So what?

[vindimy]

If you read this Wiki article:

The comoving distance from the Earth to the edge of the visible universe is about 46.5 billion light-years in any direction; this is the comoving radius of the visible universe. It is sometimes quoted as a diameter of 92-94 billion light-years.

... You will ask, "So, what's the fuss about 1bln years?" So, what is it?

And conversely...

[singingjim]

...any alien civ that might be looking for us from that star cluster is looking at the earth 1 billion years ago. Guess they won't be finding us for a while. =\

In other words...

[brian0918]

In other words, they have to say the same thing in 20 different ways to hide the fact that there is no story here.

A correction/explanation

[minuteman]

As an astronomy graduate student, I would like to offer a correction or an explanation of this statement:

From the article:
"That's because the older a star gets, the redder it gets, he says. Younger stars are bluer."

Kinda true, but the point is something else. A young *cluster* of stars will look blue because brightest stars in a young cluster are blue, massive stars. These blue bright stars burn their fuel (Hydrogen) very fast and have short lives (~100 Million years). When blue bright stars go away, more numerous, but much fainter, red stars start to dominate the color of the cluster. Therefore, as the *cluster* gets older, it gets redder.

Re:A correction/explanation

[kharchenko]

Are you sure he isn't just referring to the redshift ? This would have nothing to do with the types of starts observed.

Re:A correction/explanation

[khallow]

He's not talking about redshift. This is a common thing to look for in galaxies since it distinguishes between old areas and areas of new star formation.

Re:A correction/explanation

[Myrano]

Yeah, I'm an astronomy undergrad, and I caught this. Glad somebody cleared it up. I imagine it must have been misreported... I don't see any serious astronomer (let alone one who's looking for old stars!) mixing this up.

[OT] "Seeing" the past via non-light means

[noidentity]

"That's interesting, he explains, because given that light travels at a finite speed -- 300,000 km a second -- the light emitted from the star cluster he and Kalirai saw was emitted one billion years ago. That means the cluster as it appeared to them two months ago was the way it looked one billion years ago. In other words, they were looking one billion years back in time."

It's even more interesting when you consider other ways that we "see" the past, for example a footprint in the sand. In this "light", everything around us is a reflection of the past, so were "seeing" things as far back as history goes. Some of these things go unnoticed due to them being part of our assumptions about reality itself.

Re:If only there was a galaxy sized mirror near it

[Apocalypse111]

Correct me if I'm wrong, but doesn't Genesis say it wasn't just the earth, but the heavens as well? If we take "the heavens" to mean the rest of the galaxy as well, then should they not be the same age?
Either way, you're dismissing all the accumulated knowledge of science in favor of the superstitions of ancient sheep herders who thought that all the animals on earth were within walking distance of Noah's house. The bible contains equal parts fact, history, and pizza.

Sharp as a Tack

[Nom du Keyboard]

given that light travels at a finite speed -- 300,000 km a second -- the light emitted from the star cluster he and Kalirai saw was emitted one billion years ago. That means the cluster as it appeared to them two months ago was the way it looked one billion years ago. In other words, they were looking one billion years back in time.

Gee, figured this one out huh?

Re:Sharp as a Tack

[Achoi77]

I have a friend who just turned 30. Then I met his girlfriend. She just entered college, and she was 19.

I would tease them saying stupid things like, "You know Jim, did you ever stop to think that when you got your driver's license at 17, you would be driving up to the local middle school, pointing at a random 6 year old who just started kindergarten and be saying to yourself, 'I'm gonna bang that chic someday'? Or when you just graduated college at 22, you would be checking out the jr high student who will be starting 8th grade the following year, and be saying, 'I'm gonna have SEX with that one right there, baby!'?" They would both give me the dirties looks while my other friends and I would be laughing our asses off.

I have no clue why that came in my mind. Something about the big age differential in context always has more of an impact on others moreover than some. And while things may be obvious from a logical perspective, sometimes all it takes is a little introspection to recognize the vastness the differential is meant to provide.

Re:I RTFA and I find really F*ed

[Volante3192]

1) Well, a human eye did see the stars after it went through the Hubble. (Can the Hubble actually "see?") Note, he didn't say "naked human eye."

2) But is that 1 billion years and two months from the Hubble or from British Columbia? Related question, do you get huffy when they say 10 bil years plus 700 mil years equals 18 bil years? Significant figures.

3) ...Yea, that one's fubar.

Billion-year-old alien computer message decoded!

[kale77in]

From the article:

"Astronomers further said that they had decoded part of a computer signal from the star systems in question, possibly a signal 1,000,000,000 years old! It said, 'Please wait, Java loading.'"

Assuming the Speed of Light is Constant

[Khomar]

This article has taken great and repetitive pains to explain something that may in fact not be true. A previous ./ story talked about indications that the speed of light may in fact be slowing down. Depending on the rate of change, they could be witnessing events significantly closer to the current time -- especially when we are talking billions of years.

Re:Assuming the Speed of Light is Constant

[Citizen of Earth]

A previous ./ story talked about indications that the speed of light may in fact be slowing down.

It's a good thing they're going to increase the speed of light in 2208.

Re:Assuming the Speed of Light is Constant

[khallow]

Actually no. With the way the speed of light is defined, it is constant. Instead, the fine structure constant (or other physical constants) could be, maybe changing.

Re:Assuming the Speed of Light is Constant

[dangitman]

Light should probably go to the mechanic for a lube job, then. Or at least stop drinking and smoking.

Re:I RTFA and I find really F*ed

[smart.id]

2) And some others lines "That's interesting, he explains, because given that light travels at a finite speed -- 300,000 km a second -- the light emitted from the star cluster he and Kalirai saw was emitted one billion years ago. That means the cluster as it appeared to them two months ago was the way it looked one billion years ago. In other words, they were looking one billion years back in time." No, not one bilion years back in time, but a billion years and two months.

Is this a sick joke? When you're working on the scale of 10^9 years, .1666 years really doesn't make much of a difference. Not to mention that it's obviously not from 1,000,000,000 years exactly ago, but some number that's pretty damn close. Why get upset about such a stupid detail?

Re:If only there was a galaxy sized mirror near it

[parvenu74]

That'd be great! It'd be awesome because then you could see the earth 2 billions years ago...Wait! it didn't exist because the world's only 6000 years old...But the rest of the universe is older...? Is that comment really flamebait? I'll buy "Offtopic" since this isn't a religious-themed message board.

Here's a question for the "young earth" creationists: the math (triangulation and distance = speed * time) used in this case shows that the universe is at least a billion years old. What is your proof that it isn't? Did God create the stars with "already traveling light" to fill in what would otherwise be a 999,994,000 gap in time and distance?

And to the astronomers (since I'm not one): how many times in astronomical history has a star suddenly appeared in the sky, suggesting that its light just arrived here for the first time? I figure it has probably happened but it's not my field of study so I don't know.

earth?

[revelous]

[quote]In other words, they were looking one billion years back in time.[/quote] so when do we get to look at earth?

speed of light in Pb

[cohomology]

The index of refraction of lead is 2.6, so the
speed of light in lead is c / 2.6 = 1.1E8 m/sec.
Of course, light is absorbed pretty strongly by lead.

The index of refraction is still an important
quantity - it determines how much light is reflected
from the surface, for example.

Ha .. ha

[Anonymous Coward]

a University of B.C. astronomer recently used NASA's Hubble telescope to see a cluster of stars one billion light-years from Earth, the farthest stars ever observed from Earth.

How appropriate that is....

Crappy technical writers

[scdeimos]

I think this was a great technical achievement, but was ruined for me by the incompetance of the article. TFA kinda lost me with the opening paragraph:

A University of B.C. astronomer has discovered the farthest cluster of stars ever seen by a human eye -- a find he hopes will reveal secrets about the formation of the universe.

WTF? He used the Hubble! Did he grab a shuttle up to the Hubble, rip the sesnor pallet out and stick his head down the end of the OTA?

Also, the whole harping on about the light being a billion years old is kinda redudant. "one billion light-years." Think about it, there's a time component there.

Re:I RTFA and I find really F*ed

[Pojut]

I am going to be showing a bit of my stupidity here, but there is something I have NEVER been able to figure out...what does it mean when someone types (sic) ?

Re:If only there was a galaxy sized mirror near it

[Nethemas the Great]

You may wish to re-read your Bible. Says nothing about the universe being only 6K. "In the beginning God create the heavens and the earth. And the earth was without form and void..." The mentions about actually doing something useful by way of flora and fauna with the earth did not necessarily occur during this time period. Quite possibly this occurred later. Checking the "was" in the original language and there's reason to believe that it should well have been a "became."

There no mention of however long things were happening before, during or after the "was[became] without form and void". More over no where does it say how long Adam and Eve hung out in the garden. There's really no time references anywhere save for the first through seventh days some time arbitrarily following the initial creation.

This 6000 year crap came along much later based upon foolishly reading more into things not written. It caught on for some reason and has been the bane and laugh of most everyone ever since.

--Neth

Re:If only there was a galaxy sized mirror near it

[Diss Champ]

Well, since you asked..
The Genesis account does clearly state the light was created before the stars. Look at the order of the days. Also, the universe a whole being created before the created before the days started counting, with no time specification regarding the gap between. Whether the account is correct or not is for another analysis, but that one at least is a simple read what you're arguing with first. :)

Re:Lag

[19thNervousBreakdown]

How did you manage to get this one wrong?

Re:I RTFA and I find really F*ed

[Abcd1234]

It's used when quoting another individual, and indicates that typos or other errors are part of the quote, rather than being introduced by the quoter.

Now we know

[rocknsteady]

Cool. Now we know what light looked like a billion years ago. I bet we can project what it'll look like a billion from now!

Article for 6 year olds

[Mr. BS]

Now they hope to compare that cluster of stars with the clusters that surround our own galaxy, the Milky Way, and see if there are any differences.

My kid knows this stuff.

That means the cluster as it appeared to them two months ago was the way it looked one billion years ago. In other words, they were looking one billion years back in time.

DUH... Think so? How bad does TFA need to be dumbed down?

BTW - Haven't seen the word 'billions' so much since Carl Sagan's book! Think we got the point on the first reference!

Blue shift/red shift

[G00F]

I thought blue ment it was moving toward us, and red was away.

See the wiki: http://en.wikipedia.org/wiki/Redshift

So how reliable is using blue shift and red shift to determine both age of the star, and weither it is moving towards us or away.

So while blue star clusters could be younger, couldn't it just an older start that is moving toward us?

Re:Blue shift/red shift

[wanerious]

There's a little confusion on this. The bulk (cosmological) motion of the host galaxy away from us gives rise to an overall redshift in the spectrum, affecting all spectral lines emitted. It is true, generally, that older stars tend to be red as they expand into red giants, whereas young massive stars are blue. There are young, red stars also, but they contribute negligibly to the cumulative luminosity. So after correcting for the redshift, we can get some idea as to the type of stars in the cluster and the evolution of such stars by looking at their color.

Nah, you cant look back for more than 6000 years

[140Mandak262Jamuna]

The whole universe was just created 6000 years ago. That star 1 billion light years away is also just 6000 years old. It was created along with the stream of photons stretching all the way from here to there so that it appears to shine steadily. BTW all the dino fossils? they too was created 6000 years ago along with the Earth's crust. It will all be explained very clearly in my forthcoming book The Theory of Intelligent Shining. For advance copy, please send me 79.99$.

Re:If only there was a galaxy sized mirror near it

[porpnorber]

If I may analyse this logically(!) from a theistic view, either God did, or did not, create time. If God did not create time, then time must have been created by someone else, so God is not God, contradiction. If God did create time, then it would seem to follow that the world was indeed created 6000 years ago. It was also created 3.6 minutes ago, 20 billion years ago, and (unless the apocalypse come) Tuesday next week. To insist otherwise is a bit like a dwarf saying, so, this builder, did he make the foundations or the roof? Because the roof is above the foundations, and he couldn't have made both!

Physics is (in present terms, by definition) exactly the study of the observable. Theology is (when once you have grasped the notion of omnipotence and its implications for your ability to reason) the study of things deep into the unobservable. They cannot possibly come into conflict - unless you have gone to a lot of extra effort to believe rubbish that conflicts with both sets of thought! ;)

Re:So...

[profplump]

What you're really saying is that "now" is a spacial-local observation (i.e. it's all relative). It's not they you're sending information back in time a billion years, it that "1 billion years ago" for a distant observer actually *is* "now" for us and visa versa.

Dont be fooled by this post ....

[kryten_nl]

Don't be fooled by this post ... the article KFG links to doesn't contain any reference to ponies or horses what so ever.

Re:Dont be fooled by this post ....

[kfg]

... the article KFG links to doesn't contain any reference to ponies or horses what so ever.

The Marching Soldiers activity. . .

The mounted centenar is implicit.

KFG

Re:So...

[exp(pi*sqrt(163))]

Except that there's no known method of using entanglement to signal instantaneously and there's no theoretical reason I know of to even suspect that such a thing might be possible. I don't think the crack pipe is doing this to you, but way too much science fiction.

Distant sunrise

[Anders Andersson]

"Sunrise" is a visual event involving an observer (you), a horizon, and the Sun. Disregarding the observer, the "place" where this event happens is where the object nearest to the observer is found, and that object is the horizon, which is usually pretty close to you. The light hitting your eyes may be 8 minutes old, but the shadow from your horizon isn't.

Saying that the sunrise occurs 8 minutes before you see it is like saying that it will take 8 minutes for you to see the effect of blinking your own eyelids. That's clearly not true.

Now go visit your nearest horizon to see the sunrise happen on location, and instantly rather than delayed. :-)

Re:Looking back into the past

[IngramJames]

So if we like put up a frickin huge mirror out in the space, would we be able to see our reflections back in time?

Yes. In the same way that if you go into a valley and shout "echo", you will hear, in a second or two, a sound from the past coming back at you.

Sound goes out from you. Hits wall. Comes back. You hear it.

Light does the same thing; just a little bit quicker, so you'd better make the mirror a long way off if you want to get a noticable echo.

Or just watch the news when they are linking live by satellite to somebody who pauses for a couple of seconds after the presenter has stopped speaking.

Re:So...

[eno2001]

Whew! OK. Back to the crack.

(Pick pipe up again after encouragement by random Slashdotter)

Re:I RTFA and I find really F*ed

[Pojut]

...thank you SO fucking much.

That has been bugging me for years.

Only 1 (one) billion light years? Aww, come on.

[Almost-Retired]

I note with a certain amount of scientific curiosity and indeed scepticism that nowhere in the article is the effective red shift for this one billion light year distance noted. This seems like a designed in effort to get some ink with no real hard data to prove that claim because its the red shift times the hubble that is the usual astronomical yardstick for measuring such distances.

I don't know how to convert from hubble constant, eg red shift, to distances, but we do have a couple of spots on the images here and there whose red shifts have approached if not exceeded 5.0. Meaning they are so far away that a given line in their spectrum has been red shifted until it is now 5 times its original wavelength. Considering that the visible universe has now been calculated at 13.7 billion light years, the age of the universe in other words, and we cannot see beyond because it would be effectively looking back before the big bang. When we do look back that far, what we see is the afterglow of the big bang in the nominally 2.7 degree Kelvin radiation that permeates the universe we can see.

Someone more versed in the math should tell us what the red shift is at 1 billion years, but I have serious, really serious doubts that its much more than 1.9 or so. If thats true, then this claim should be treated for what it is, another grant money grab. Someone throwing out big numbers because the real red shift numbers aren't that big.

Now, somebody do the math and correct me if I'm grossly wrong.

--
Cheers, Gene

Re:Only 1 (one) billion light years? Aww, come on.

[GumphMaster]

Using http://astronomy.swin.edu.au/~elenc/Calculators I get a redshift of z=0.073 roughly equal to 1 Glyr (approx 307 megaparsecs)

One Billion Years, Or???

[Scarletdown]

That means the cluster as it appeared to them two months ago was the way it looked one billion years ago.

Shouldn't that be the way it looked one billion years and two months ago?

One thing they forgot to teach you...

[Vr6dub]

It's a joke dummy.

Haha, jokes, I get jokes. /homer

The universe to scale.

[FridayBob]

Your teacher was way, way off. Ten years ago I created a spreadsheet for myself to get a better idea of how big our universe is.
One of the calculations scaled 1 AU (Sun-Earth distance) down to 1 mm:

Sun to Earth: 1.0 mm
Sun to Mars: 1.5 mm
Sun to Jupiter: 5.2 mm
Sun to Saturn: 9.6 mm
Sun to Uranus: 1.9 cm
Sun to Neptune: 3.0 cm
Sun to Pluto: 4.0 cm
Sun to Kuiper belt: 4.0 cm
Sun to Oort Cloud: 10 m
Sun to Proxima Centauri: 267 m
Sun to Tau Ceti: 772 m
Milky Way galaxy diameter: 6,327 km
Milky Way to Andromeda galaxy: 139,200 km
Milky Way to galaxy 0140+326RD1*: 759,000,000 km'

*) At 12 billion light-years, the farthest known galaxy at the time.
') Almost as far as Jupiter is from the Sun.


Conclusion: the universe is really, really, really, really big. It makes the idea of even reaching the next star seem like a pretty wacky proposition.

Actually a lot older...

[johnnyk427]

Stars have been around a lot longer than a billion years, and there should be plenty earlier still visible.. I seem to remember they just found some very early generation stars closer to 12 billion years old (a billion years after the big bang), making it much older than the ones mentioned here.

They even mention them in the article:

Last year in Prague, Richer had the distinction of introducing to the International Astronomical Union the first hard evidence of when the first stars formed -- about 12 billion years ago, or a billion years after the universe began.

He did that by identifying and photographing the faintest stars ever seen, because the fainter a star is, the older it is. I think the article is a bit off on the actual facts, maybe they meant the stars theyre seeing now were formed a billion years after the big bang? They contradict themselves.

In any case, stars a billion years old aren't that exciting, its the 12 billion year ones, at the edge of observable space that get things interesting (they're early-generation stars, formed of primarily hydrogen as opposed to other later-generation stars that are formed of hydrogen plus heavier elements created by previous long-dead stars. So the earlier ones have a lot different properties and can get a lot larger)

Hubble Ultra Deep Field is 13 billion

[gootar]

What gives... this is 13 billion year http://antwrp.gsfc.nasa.gov/apod/ap040309.html the new one is only one billion?

What about 13billion yr old galaxies?

[jammaramma]

I don't understand why this is such big news. There are pictures of galaxies that go back to less than a billion years after the big bang, i.e about 13 billion years. Here's one: http://www.newscientist.com/article.ns?id=dn4756. Now that is fricking amazing. There are better photos, I just did a quick Google to get this one.

When the light left those galaxies/quasars/whatever 13 billion years ago, the universe was much smaller than it is now. So that 13 billion light year radius sphere surrounding us was only a 500 million light year sphere at the time, yet the light has taken 13 billion year to get here. (Actually, the universe is not really a sphere. It's some warped dimensional thing that I can't possibly understand.)

So what's the big deal about 1 billion light years?

Re:What about 13billion yr old galaxies?

[gootar]

Hey... where did you get this from...

When the light left those galaxies/quasars/whatever 13 billion years ago, the universe was much smaller than it is now. So that 13 billion light year radius sphere surrounding us was only a 500 million light year sphere at the time, yet the light has taken 13 billion year to get here. (Actually, the universe is not really a sphere. It's some warped dimensional thing that I can't possibly understand.)

I've been looking for information like that.

Ummmm....

[multimediavt]

Didn't they determine that the universe was 15 billion years old (there abouts) because they observed light from stars 15 billion light years away? That's what I remember from intro to astronomy anyway. Plus, look at this http://hubblesite.org/newscenter/archive/releases/ 2007/01/image/a/format/web_print doesn't that say 6.5 billion years ago, as in the light observed has traveled 6.5 billion light years? So what's the big deal about one billion? I don't get it. Oh wait, he was standing on the planet Earth when he saw them...ok, big whoop.

Get a clue, please

[spaceyhackerlady]

Why can't they point hubble at Mars and other nearby planets and get some decent images. If they are so good at preparing the images mathematically. Makes you wonder doesn't it? The images we have received so far from Mars are a joke compared to the teraserver or maps.google.com images of earth. Makes you think NASA is more focused on research that discovery.

There is nothing to wonder about at all. Hubble's resolution is fixed by the the size of its mirror and the wave nature of light. The seeing is perfect in space, but you can only see so much with an objective of a particular size. With adaptive optics and various sorts of image processing, ground-based telescopes now equal, or even exceed, Hubble's resolution. In space they would do better, but on the ground they are very good.

The Hubble pictures of the planets are more than "decent", and they're far from a joke - they're excellent. What more do you want?

...laura

Someone tell Steven Colbert

[Barlo_Mung_42]

We are now letting Canadians use our telescope and take credit for the things they happen to see through it? What is the world coming to?!?

You insensitive clod!

[cadu]

3rd world country: how much is that in SOCCER fieldS?

ah! now i get it! :P

Patronising? Or just stupid?

[1u3hr]

What is this, Sesame Street? The submitter, and the editors, thought the msot interesting paragraph to excerpt was the one explaining that it takes light one year to travel one light year?

In other news, a 300 Watt power supply uses as much power as three 100W light bulbs (I think that line was actually used here a few months ago.)

You're looking at it all wrong...

[tpjunkie]

Stop thinking of photons as particles. There are times and places where it's convenient and simple to think of them as such, but quantum entanglement isn't really one of them. To make any sense of it, you need to consider each as an entangled wave function. Unobserved, you can have each particle take any arbitrary number of paths through space time, which allows for interference patterns and fringes. Once you observe one part of the entangled wave function, you have collapsed BOTH of them, resulting in a particular outcome for the entangled photons.

Re:You're looking at it all wrong...

[(negative video)]

Wavefunction collapse is a formal convention, like virtual particles. It has several nasty epistemological questions, such as How fast does the collapse propagate? and How does the collapse know to limit itself to a single event when the wavefunction is dispersed over a large volume? The naive answers are "instantaneously" and "damned if we know". For entanglement of uncharged particles like photons, there are also the sticky problems of Which force is creating the bound state? and What is the binding energy? "Shut Up and Calculate" will give you your diffraction patterns, but doesn't give you any insight into the underlying reality.

Re:If only there was a galaxy sized mirror near it

[Apocalypse111]

Well, your assumption that I own a bible aside, I was not trying to say anything about the age of the earth and the galaxy, merely trying to use logic (in response to a religious post? what was I thinking?) to try to show what I thought was an error in the parent's post.

Re:If only there was a galaxy sized mirror near it

[cascadingstylesheet]

>What is your proof that it isn't?

That God says so.

Actually, I wasn't claiming that I had "proof", but
*you* are (or at least, that you have "proof" to the
contrary).

>Did God create the stars with "already traveling
>light" to fill in what would otherwise be a 999,994,000
>gap in time and distance?

Maybe. You're not getting this "all powerful" thing, are
you? ;)

Anyway, what with all the time dilation and other exotica
involved in this topic, I'm not sure this is the place to
play arrogant creation-basher ...

Re:Spaceballs

[treeves]

But you had no trouble refraining from using any HTML tags that might make your post more readable!

40, 41, 43, 44, 45....

[El_Oscuro]

I think the planet of Magrathea is about 6000 light years away. When Slartibartfast was designing the Fjords and subcontracting the installation of the fake dinasour fossils, the mice who were running the factory and building the Earth realized they had a major problem:

Someone had accidently made a typo on the decimal place in the progress bar subroutines, so instead of taking about 5 to 6 thousand years, the program would take 5 million years.

The project was hopelessy behind schedule, over budget, and doomed. The only thing the mice could do was push the project in time until the program had sufficent time to complete, even before Deep Thought had been created. Deep Thought and The Answer disapeared, lost in time forever. Postcards of Deep Thought suddenly became very valuable.

No one had heard of the answer until a woman asked the question "what do you get if you multiply 6 times 7?"

Then the Vogons arrived...