Yah, oddly enough, people have made bad predictions before.
But note that they didn't suggest human action was the culprit then. There was nothing people could do except prepare for possible change to minimize any impact a changing climate could have upon the food production.
Things are different now - climatologists are saying that there is something we can do. And just as it would've been naive to ignore their concerns before, it's incredibly naive to ignore them now.
This isn't a "boy who cried wolf" scenario. A large percentage of climatologists would agree that restricting greenhouse gas emissions is extremely necessary and is vital to ensure the stability of the ecosystem.
What cracks me up is that so many people think that it's crazy that the humans could affect weather on a global scale. This is insane - we've affected the CO2 level on a global scale. We've raised the global CO2 levels almost 25%. We have changed this planet. The only question is how the atmosphere is going to respond to those changes.
What I want to know is to what extent do the various climate models take into account variations in solar energy output?
Variations in solar energy output matter less than eccentricity variations in the Earth's orbit. Those variations are most directly responsible for ice ages/heat waves. A large part of the temperature increase is likely due to eccentricity changing. However, if you look at ice core trends, you'll note that spikes in CO2 lead to spikes in temperature, so it's naive to think that all of the temperature increase is natural.
After all, global CO2, methane, etc. are all at their highest levels ever. It's silly to think that while we can change the atmosphere globally, that weather change doesn't follow.
Worse, leave it to the theoretical physicists, because no physicist has ever observed a triangle with angles not adding up to 180 degrees.
Wow, talk about hubris!
Define a straight line: the best mathematical definition for that is the "minimum distance between two points", right? In the real world, that's the path followed by light in a vacuum. Always. By definition of "distance".
Physicists have certainly seen deflection of light from a Euclidean straight path. Gravitational lensing is the best example of this, but they've measured it from bending around the Sun, for instance.
So take that bent path, and take any other two straight paths and form a triangle. Boom, instant triangle with angles not adding up to 180 degrees.
"It's better to have a gun and not need it than need a gun and not have it." ~ Christian Slater, True Romance
Curiously, wouldn't this imply that it's better to cut CO2 emissions, and not have had to, rather than to have needed to cut CO2 emissions, and not done it?
like the maunders minimum and the other variations of temperature in historical times in which the Impact of human activity was, by today's standards, negligible.
The Maunder Minimum describes sunspots - the Little Ice Age is what you're referring to. The times were close, but the two labels are not the same.
If the people of Europe, at the time of the Little Ice Age, had any reason to believe that their actions were causing the cooling of the planet, it would've been incredibly foolish for them not to have taken action. But they didn't have any reason to believe that.
Here are the facts:
The planet is warming up. All data so far show that the average global temperature is rising.
CO2 levels are rising. The predominant source of rising emissions is human activity.
We do not know conclusively that the human activity is causing the warming, however, basic physics says that a higher level of CO2 in the atmosphere leads to a higher temperature.
We do not know that we are the source of the warming. That's correct.
But as another poster put it before, suppose you are accelerating towards a brick wall. If someone tells you "the brick wall will go away before you get there", and someone else tells you "the brick wall will not go away before you get there", aren't you going to at least start slowing down??
I doubt there'd be much D outside the active part of the core, as a) it's only produced in the active part of the core, and b) as the active region shrank as the star lost mass, it would be surrounded by a region in which D could still burn - so the D left in the areas that were once core would be burned up almost immediately.
I was actually thinking about the unburned D in the outer stellar envelope. I'm not sure how much there would be, though - I can't find measurements of the Sun's deuterium abundance in the outer region of the star. The reason I was saying so is that with hydrogen burning, the star actually stops burning hydrogen far before it runs out of hydrogen in the star - it's just that the outer shell hydrogen has no chance to reach the core so long as the star burns at all. Likewise, the primordial deuterium in the stellar envelope for this star would've been unable to reach the core so long as the star was burning, but after fusion ceased, it should've sunk down to the core, only to reinitiate fusion briefly.
It should be noted that as the star collapsed, before it started burning, D would've sunk to the core as well, so you could be right.
We know what Jupiter's outer atmosphere is made of, and that's all we'd need to know for this thing, as after it hit the "red dwarf" stage, it would lose most of its internal structure. As far as I can see, all of the remaining material should be from the core of the original, larger star, so the atmosphere should represent a reasonable sample of what that original stellar core contained. If I'm overlooking something, by all means let me know.
I doubt the outer atmosphere would bear much resemblance to the "old" inner core of the star: the core would contain the heaviest elements, and the outer atmosphere would be primarily hydrogen. It would depend a lot on the exact mass loss mechanism and the density profile of the dying star, actually! The sun's 'burning region' is quite large - fusion is occurring in almost 1/3 the radius of the Sun. For a dying star that was losing mass very slowly, the core would shrink slowly over time, and in the end, the outer region of the star would be quite different than the interior (because it was the star's 'core' long ago). But if was losing mass quickly, then the star would be more uniform.
As I said before, though, it's an amazingly interesting object. I think 'brown dwarf of a new spectral class' is actually appropriate for a name, though.
Google's been told that there's a bias in the search (remember, you're supposed to be searching on -topics-, not words), and they've responded and said that there's no bias, because the algorithm doesn't care. Apparently no one at Google understands that an unbiased algorithm can generate a bias if there are biased assumptions founding the algorithm - namely, that phrases of interest are used equally throughout news sources, therefore news sources that contain more of the phrases are more of interest.
By not doing anything about it, it's an intentional bias. It's not a liberal or conservative bias, but it is a bias.
So little, if any, D and Li should have been available at the time pp fusion ceased.
You're right that the D and Li phases wouldn't last much longer afterward pp stopped, though it depends on the mass loss rate. But there would've been a fair amount of D and Li available.
Actually, the D burning would continue probably for quite some time due to hydrodynamics, now that I think about it. While fusion was occurring, the turbulence inside the star would dominate the hydrodynamics, so D would remain mixed throughout the star. Once the fusion stopped, deuterium, being denser than hydrogen, would naturally sink slowly to the core. So you probably would have "fits" of deuterium burning (which remixed the deuterium) as the star slowly burned up its deuterium.
It will be able to pick up absorption lines, as this thing does have an atmosphere.
That's what I meant, though again it depends on the density profile of the object. The core of the object is likely too dense to let anything pass through it. We don't know what the core of Jupiter is made of - this object is something like 50 times denser.
The core composition is the interesting part, unfortunately. For that we'd need to be there.
If it's defined as a "star that is no longer burning", though, this would qualify.
That's what a stellar remnant is, not a black dwarf. A white dwarf is also a star that's no longer burning - it's white because it's still hot. Black dwarves are white dwarves that have crystallized. There's a specific definition because there's a phase transition (crystallization) that they have to go through, so there's a clear dividing line between white dwarves and black dwarves.
I even seem to recall that there was a white dwarf at around 11 LY that we could study.
Sirius B. First white dwarf ever discovered. Problem is it's sitting right by Sirius A, which is *not* a white dwarf - it's a blue-white supergiant. That must've been a hell of a system when it was active... The nice thing about this system is the fact that it's a bare white dwarf. Plus it has an interesting companion. Bonus.
That would let us image stellar atmospheres
We actually already can image stellar atmospheres. Only big stars, but stellar atmospheres nonetheless.
Here's an example. I used Betelgeuse because I think it was the first and only star for a while. I think there've been more by now...
Since it's a binary system, we'll assume that the two are cosmologically the same age, meaning that whatever generation they are, we're looking at roughly the same elemental mixture at birth (ignition), which we should be able to get from the dwarf's (vampire's) stellar spectra.
They're not the same mass, though. And since the white dwarf companion is - well - a white dwarf, it obviously was far more massive. It burned out first, for one.
A white dwarf's elemental composition, moreover, is not a good indicator of its original composition - just of its mass. It's a stellar core, after all - it's almost all carbon, with heavier elements inside in shells that again, depend on the mass of the star, and very little on its elemental origin.
I'll further posit that as the vamp star went through the nova phase, between 30 and 50 percent of the expelled mass would have been absorbed by the donor star (they're that close), but this would have been mostly composed of the lighter elements.
Yah - but the mass came *from* the donor star originally! It basically gets back a fraction of what it gave (although much less than 30%, I imagine - the shell is ejected with extremely high velocities. Fusion's powerful, after all).
However, remember that as the vamp absorbs matter (mass), it's gravitational attraction increases.
Not significantly. The amount of matter accreted that actually *stays* on a white dwarf is quite low. You need heavier elements (not H, He) to do that, and that's a tiny fraction of what it accretes (since it primarily accretes H). That's why it takes so long for Type Ia supernovae to occur, which is good - it allows the planetary nebula to be far from the star, so we can observe the supernova directly.
I'm still wondering what made the process stop.
So are astronomers. Most likely it's simply the fact that the other star is too dense - without fusion, the star would contract, and become more dense, though the lighter layers would separate, and continue to be accreted by the white dwarf.
Eventually, however, the starved star will fall into the white dwarf. Which will produce a *big* nova (but just a nova - not enough mass for a Type I supernova) and a slightly larger white dwarf.
I can't see how this is a revalation, more of just finally finding something of the right size.
It's the same size as a brown dwarf. The problem was that no one had found anything that's the same size as a brown dwarf, but not a brown dwarf (i.e., an object condensed from a nebula/disk but not large enough to complete the pp-chain at its core).
Things are classified typically by mass and composition. Almost everything falls into certain classes by those rules (stars, brown dwarves, white dwarves, planets, neutron stars, black holes, etc.). This falls well outside of any previous category of object. It's way interesting, too - its composition might reveal a lot about plasma physics and the interior structure of stars.
Thus, the star should have used these up very early in its life.
Deuterium and tritium are byproducts of the pp chain - the star constantly regenerates them.
Once the pp chain stops, deuterium burning will continue for a while (stars are *big*, after all) but would, eventually, stop.
Spectrography might be able to detect the relative ratios of deuterium, etc. in the object, but not likely - its core is still quite dense, and there's little light being generated from there.
Pretty broad category, so probably not specific enough. Also tends to refer to things like planetary nebula and not stars (we haven't seen anything star-like that's been around long enough to cool down past "white dwarf" levels).
Stellar remnants are a broad class which encompasses anything left after a star has left the main sequence (planetary nebula, black hole, white dwarf, neutron star, etc.). This *is* a stellar remnant, though it doesn't have any classification within the stellar remnant class. Planetary nebulae are actually former stars. The former star is sitting at the center of the nebula.
This kind of object really does need a new classification - it's a new way for a star to die. I vote for "starved star", though it's not like my vote means anything.:) "Bulemic star" would probably be too non-politically correct.
The problem in naming is that mass doesn't define everything - composition is the other issue. A brown dwarf has the composition of the protoplanetary disk, slightly modified by fusion (lower concentration of D, higher concentrations of products of D fusion). A black dwarf is an almost entirely pure carbon diamond.
This object certainly is not a black dwarf - it's not a degenerate object, for one. It's also certainly not a brown dwarf - compositionally, it's totally different.
Keep in mind that this star was probably burning on the main sequence - burning, probably quite actively, for billions of years alongside its "partner" star. Virtually all of its internal composition probably bears little resemblance to the protoplanetary disk - it's been heavily changed by fusion and by virtue of having been *plasma* for that long.
What amazes me is that it's 300 light years away. 300 ly! That's virtually in our backyard! Jeez, if someone ever develops faster-than-light travel, this would be one of my first stops for astrophysics. In all seriousness, though, it'd be on my top list for observations when the next class of optical telescopes develop. A white dwarf, and a star frozen in development. And only 300 ly away.
Makes me wonder how many more of these they'll find.
MACHO.
MACHO, as you noted, means "massive compact halo object". This object isn't in the galactic halo. Therefore it's not a MACHO.
If you aren't informed enough by theories of time and space, don't say they don't exist.
Trust me, I know quite a bit about general relativity. I know that GR doesn't forbid closed timelike loops - but I also know that any solution involving closed timelike loops also must involve matter of exotic type, or objects where GR may break down (like black holes, etc.).
But it's naive to say that time travel might be possible with enough energy. Time travel, if it exists, will require significantly more than just energy.
And besides, like I said in a different post: jeez, who cares about time travel? Time travel implies the existence of faster-than-light travel (because... time travel *is* faster than light travel). I'd much rather faster-than-light travel exists - but right now, any physicist who knows enough about the situation would have a very healthy amount of skepticism. And if they don't, they're the ones who are on a high horse, not me.
Best story about mongoose being introduced into Hawaii - they were introduced to control the rat population.
One problem: rats are nocturnal (night-dwellers). Mongoose (at least the kind introduced to Hawaii) are diurnal (day-dwellers). The two species barely ever saw each other.
Could the dwarf star absorb enough mass that fusion could start again? That would be awesome!
This is what novae are (not supernovae, which are different). When a white dwarf star accretes matter, it builds up on its outer shell. Since the white dwarf is incredibly dense, its gravity is incredibly strong, so the layer of matter (hydrogen) is incredibly hot. Eventually the density of hydrogen grows enough that fusion can occur again, and it does - and the star burns off (very quickly - ~few days) what took it several years to build up.
This causes a white dwarf to go from barely visible to extremely bright. In the night sky, it looks like a new star comes out of nowhere, then disappears - hence the word "nova", meaning 'new'.
If there's no nuclear fusion in its core, it's not a star.
Actually, this object is incredibly interesting. Composition-wise, it's a star frozen in time, and without all the nasty chemical-changing properties of nuclear fusion going on. There's a lot that could be learned from objects like that.
I have to admit, the original parent isn't being a complete lunatic on this one... except, for this, you have to accept that cosmic strings can exist, and that general relativity is valid in that regime.
There are plenty of theoretical possibilities for time travel within GR, but none of them are really tractable.
One of the big problems is the fact that people have basically ended up playing with odd metrics in GR, coming up with bizarre geometries, and then finding out that the matter requirements to generate such a metric are very weird, and usually involve weird matter (like "negative energy density" matter). In your case, it's slightly different - the author started with weird matter (cosmic strings) and said "hey, weird stuff can come from that."
The problem is that I can't imagine real physicists believing that said "weird matter" is actually real at this point. Many of them might *hope* that it's real (hey, it'd be fun) but if you look at it objectively, the odds are definitely against it.
Don't get me wrong, time travel would be nice (well - actually, faster than light travel would be nice, and time travel is automatically faster than light travel) but there are no 'clear cut' "this must be possible" cases in physics yet. Any physicist who's being honest to himself would have to say that it's not likely.
Physicists don't drink the kool-aid on global warming. If you can prove that global warming is happening, then that is one thing. Trying to prove it is a bad thing is something else.
Um. Huh? Physicists are smart enough to know that carbon dioxide is a greenhouse gas, and that the Earth has a limited capacity to absorb it. Long term temperature trends show pretty clearly that the Earth is warming up. Much of it may be due to orbital eccentricity drift, but the problem is that CO2 levels are spiking dramatically (due to human activity) as well. This hasn't happened in any period of Earth's history that we can study.
Physicists would also be smart enough to know that the question isn't whether or not global warming is happening (it clearly is - the top five warmest years on record have happened since 1997, and if you look at the average global temperature, it's clearly going up) but whether or not human activity is causing it. And the problem with this is that we don't know enough about Earth to say it. We don't have a "control Earth". We know that humans are dumping huge amounts of CO2 into the atmosphere - far more than natural causes. We don't know what that will do. Any physicist worth his or her salt would know that this is, to quote a paleoclimatologist from Ohio State, "is a dangerous, uncontrolled experiment."
Bush is saying "well... we don't know what dumping huge amounts of CO2 is going to do... so we're going to keep studying it (while continuing to dump CO2) and if it turns out that it was bad... then we'll stop it". This is insane. It's a very dangerous, very stupid experiment we're playing with by burning huge amounts of fossil fuels.
If there's one thing Physicists love to talk about it is energy. No one understands what energy is better than physicists. Energy is the end-all idol they worship, if they worship any idol at all. How do we exploit the energy out there? How do we get more and more of it delivered to the masses? If it were up to physicists, we would be doubling our energy production every ten years. There are so many useful things you can do if only you had enough energy! Even time travel is possible with enough energy!
What in the heck are you talking about?? Physicists would also know that any energy you produce has to go somewhere. And unless we start moving off this planet (which is one thing where Bush is correct - if he wasn't saying it just to be politically correct, as is evidenced by the fact that he didn't back it up in NASA's budget) that energy is going to be dumped somewhere on Earth. I could probably do a back of the envelope calculation figuring out how long it would take to incinerate Earth if our energy production doubled every ten years, but it's not worth the effort. Given that it's exponential growth, though, that number would be well less than probably 100-200 years.
And I really, really challenge you to find a real physicist who honestly believes that time travel is possible with enough energy.
Bush is willing to shovel the money they need into their labs.
News to all of the physicists I know. Well, those that aren't working on weapons programs.
(at the expense of matter in the universe, of course)
And several conservation laws of physics, as well.:)
That being said, antimatter may just be a battery, but it is the best possible batter known to very, very basic physics (i.e. it's very unlikely to find a better one). Antimatter would be a very viable fuel for a lightweight probe to other star systems. A few have been proposed - I don't think anyone's taken them seriously, though. (AimSTAR is the one I knew of from a professor at Penn State, though it was definitely a pipe dream.)
No - because in one case, you're attacking the argument, and in another case, you're attacking the person. You need to actually be attacking the person for it to be a real ad hominem attack (which means against the person - not against the argument).
Claiming that an argument is likely to be untrue because it contains logical fallacies is simply true - if an argument has X points, and (X-1) are actually logical fallacies, then it has only 1 point which is a valid point in the argument. If the opposition has X points, of which only 1 is a logical fallacy, then it has (X-1) points which are valid points in the argument. Assuming X is larger than 2, then the argument with fewer logical fallacies is likely to be correct.
One overzealous judge could in fact slow down the process such that we have another 9-11-type calamity on our hands.
If the authorities had clear-cut proof - or even strong belief - of an imminent danger, they could "just act" - there are provisions in the legal system to protect them in those cases.
If they go before a judge, they don't have a strong belief that the danger is real. It's just a suspicion, and that's what the legal system is for.
Hindsight is perfect - we can always look back and say "they should've noticed this", or "this judge held things up so that they couldn't do this". But we will always be able to do this -regardless of how much we curtail our freedom, after something happens, we will always find someone to blame!
Typically, only 51% to 60% of the population in a given area shares his beliefs. So, the other 40% to 49% simply don't exist? Under Winner-Takes-All, they certainly aren't represented at all.
If those 40-49% really felt strongly about it, they could push their state government to change it. State governments tend to favor minorities (as does the federal government).
As I said, it's certainly possible that those states would prefer to have the Winner Takes All system - because it gives their state a larger voice.
In other words, the 40-49% are happy because they knew if they got another 2-10% of the vote, they'd get all of the electoral votes, not just some.
As Charles Dodgson (Lewis Carroll) discovered, there is no way to make voting fair (all the other voting methods - instant runoff, and the various Condorcet schemes - have weaknesses as well). The best way is to make sure that everyone knows the rules.
That's a minor form of taxation without representation.
Montana doesn't provide a fraction of a President. They vote for one.
They don't have any control over how those taxes are spent. They have an equal say in who decides how the government's laws are executed, but that's because the state bears similar risk with California. They have a complicated say in how those taxes are spent (via Congress).
Keep in mind that each state is a semiautonomous entity with its own laws, police, and bureaucracy. If you think about it in terms of costs, while Ohio has a population of 10 million, and New York has a population of 20 million, New York's operating costs are likely not twice that of Ohio, because the bureaucracy itself has an initial overhead cost, and then some scaling cost with population.
Of course, that's exactly what the Electoral College works as - an initial "overhead vote" of 2 people, and then a scaling cost with population (1 vote per so many people, with a minimum of 1 vote).
The only way to make the Electoral College consistent with the way the rest of the US works would be to abolish the existence of states entirely, which is counter to what the US was founded upon.
"Power in proportion to your population" is somewhat different from "completely ignore"
If everyone in California thought independently, I'd agree with you.
However, the simple fact that distinct mindsets exist in certain areas (why does Bush always win certain states? because the population in that area has concerns/beliefs that mirror his. The area drives the mindset) indicates that this isn't true.
followed by a national amendment to impose one allocation regime on all states
What if one community doesn't want to have that kind of voting? What if people want to live in California because California is a "winner take all" kind of state?
Funny thing is that the Electoral College system creates tyranny of the majority- within each state.
Depends on how the state wants to distribute its votes. The Constitution leaves that open to the states to decide.
It's less worrying to have state's decisions be driven by the majority than it is to have the country's decisions be driven by the majority. States are at least geographically close. One can't expect the worries of the population of Maine to correspond with the worries of the population of Hawaii, but it's reasonable to expect the concerns of the population of San Francisco to correspond to the concerns of the population of Los Angeles.
Let's use Texas as an example (although something similar happens in most states). There are a majority of Republicans and a minority of Democrats. When they vote for President, however, ALL the electoral votes go to Bush, instead of the Democrats sending their 30% to Kerry.
This is not a fault of the Electoral College. It is a fault of Texas, which decided that all of its electoral votes go to the winner of the popular vote. Other states do it differently. I won't argue if you try to say that states should do a better job at breaking up electoral votes, possibly by district. But that just redefines what "community" is, that's all.
If Iowa was really important, then the voters in California would see that (especially when they start paying those farmers for food).
In a perfect world, the sun would shine every day and I could pluck money from the money tree. And in that world, what you say would be true, and no one would have to worry about the tyranny of the majority, because the tyranny of the majority really would be the will of the people.
We don't live in a perfect world, and the tyranny of the majority is real.
PS. The use of the word "expense" in your post was completely nonsensical. In that sentence, "at the expense" should've been "in favor".
And you mean "complete nonsense", not "completely nonsensical", which is poor grammar.:) But yah, it was a typo.
True. But aside from the force of tradition, it's hard to defend why we need to enforce fairness amoung states, since states are not alive. Shouldn't we care more about actual people than states?
No.
For one, it avoids tyranny of the majority - something that's very, very difficult to deal with. For two, it allows a more even distribution of resources, and allows the country to utilize its resources efficiently.
The problem is pretty simple - people in communities tend to vote similarly, because they have the same concerns. People in California are less likely to be concerned about farmers in Iowa, for instance. Equal voting would mean that California would far, far outrank Iowa (more than it does). But that would also imply that Iowa's not important - and it is. Neglecting Iowa at the expense of California would mean that you'd essentially create a mecca of civilization, surrounded by an expanse of decaying towns.
This is exactly the case in a lot of other countries - specifically, Argentina, where Buenos Aires is akin to a first-world country, and everywhere else might as well be a third world country.
(Point of note: it only ensures fairness among states in that it gives two votes per state, and has a minimum number of representatives of one. Other than that, population reigns. Hence the reason why Wyoming ranks so high - because the population's nothing.)
Slashdot Mirror
Yah, oddly enough, people have made bad predictions before.
But note that they didn't suggest human action was the culprit then. There was nothing people could do except prepare for possible change to minimize any impact a changing climate could have upon the food production.
Things are different now - climatologists are saying that there is something we can do. And just as it would've been naive to ignore their concerns before, it's incredibly naive to ignore them now.
This isn't a "boy who cried wolf" scenario. A large percentage of climatologists would agree that restricting greenhouse gas emissions is extremely necessary and is vital to ensure the stability of the ecosystem.
What cracks me up is that so many people think that it's crazy that the humans could affect weather on a global scale. This is insane - we've affected the CO2 level on a global scale. We've raised the global CO2 levels almost 25%. We have changed this planet. The only question is how the atmosphere is going to respond to those changes.
What I want to know is to what extent do the various climate models take into account variations in solar energy output?
Variations in solar energy output matter less than eccentricity variations in the Earth's orbit. Those variations are most directly responsible for ice ages/heat waves. A large part of the temperature increase is likely due to eccentricity changing. However, if you look at ice core trends, you'll note that spikes in CO2 lead to spikes in temperature, so it's naive to think that all of the temperature increase is natural.
After all, global CO2, methane, etc. are all at their highest levels ever. It's silly to think that while we can change the atmosphere globally, that weather change doesn't follow.
Worse, leave it to the theoretical physicists, because no physicist has ever observed a triangle with angles not adding up to 180 degrees.
Wow, talk about hubris!
Define a straight line: the best mathematical definition for that is the "minimum distance between two points", right? In the real world, that's the path followed by light in a vacuum. Always. By definition of "distance".
Physicists have certainly seen deflection of light from a Euclidean straight path. Gravitational lensing is the best example of this, but they've measured it from bending around the Sun, for instance.
So take that bent path, and take any other two straight paths and form a triangle. Boom, instant triangle with angles not adding up to 180 degrees.
That's been observed quite a lot.
"It's better to have a gun and not need it than need a gun and not have it." ~ Christian Slater, True Romance
Curiously, wouldn't this imply that it's better to cut CO2 emissions, and not have had to, rather than to have needed to cut CO2 emissions, and not done it?
The Maunder Minimum describes sunspots - the Little Ice Age is what you're referring to. The times were close, but the two labels are not the same.
If the people of Europe, at the time of the Little Ice Age, had any reason to believe that their actions were causing the cooling of the planet, it would've been incredibly foolish for them not to have taken action. But they didn't have any reason to believe that.
Here are the facts:
We do not know that we are the source of the warming. That's correct.
But as another poster put it before, suppose you are accelerating towards a brick wall. If someone tells you "the brick wall will go away before you get there", and someone else tells you "the brick wall will not go away before you get there", aren't you going to at least start slowing down??
I doubt there'd be much D outside the active part of the core, as a) it's only produced in the active part of the core, and b) as the active region shrank as the star lost mass, it would be surrounded by a region in which D could still burn - so the D left in the areas that were once core would be burned up almost immediately.
I was actually thinking about the unburned D in the outer stellar envelope. I'm not sure how much there would be, though - I can't find measurements of the Sun's deuterium abundance in the outer region of the star. The reason I was saying so is that with hydrogen burning, the star actually stops burning hydrogen far before it runs out of hydrogen in the star - it's just that the outer shell hydrogen has no chance to reach the core so long as the star burns at all. Likewise, the primordial deuterium in the stellar envelope for this star would've been unable to reach the core so long as the star was burning, but after fusion ceased, it should've sunk down to the core, only to reinitiate fusion briefly.
It should be noted that as the star collapsed, before it started burning, D would've sunk to the core as well, so you could be right.
We know what Jupiter's outer atmosphere is made of, and that's all we'd need to know for this thing, as after it hit the "red dwarf" stage, it would lose most of its internal structure. As far as I can see, all of the remaining material should be from the core of the original, larger star, so the atmosphere should represent a reasonable sample of what that original stellar core contained. If I'm overlooking something, by all means let me know.
I doubt the outer atmosphere would bear much resemblance to the "old" inner core of the star: the core would contain the heaviest elements, and the outer atmosphere would be primarily hydrogen. It would depend a lot on the exact mass loss mechanism and the density profile of the dying star, actually! The sun's 'burning region' is quite large - fusion is occurring in almost 1/3 the radius of the Sun. For a dying star that was losing mass very slowly, the core would shrink slowly over time, and in the end, the outer region of the star would be quite different than the interior (because it was the star's 'core' long ago). But if was losing mass quickly, then the star would be more uniform.
As I said before, though, it's an amazingly interesting object. I think 'brown dwarf of a new spectral class' is actually appropriate for a name, though.
Ummmm, care to back this up?
Google's been told that there's a bias in the search (remember, you're supposed to be searching on -topics-, not words), and they've responded and said that there's no bias, because the algorithm doesn't care. Apparently no one at Google understands that an unbiased algorithm can generate a bias if there are biased assumptions founding the algorithm - namely, that phrases of interest are used equally throughout news sources, therefore news sources that contain more of the phrases are more of interest.
By not doing anything about it, it's an intentional bias. It's not a liberal or conservative bias, but it is a bias.
So little, if any, D and Li should have been available at the time pp fusion ceased.
You're right that the D and Li phases wouldn't last much longer afterward pp stopped, though it depends on the mass loss rate. But there would've been a fair amount of D and Li available.
Actually, the D burning would continue probably for quite some time due to hydrodynamics, now that I think about it. While fusion was occurring, the turbulence inside the star would dominate the hydrodynamics, so D would remain mixed throughout the star. Once the fusion stopped, deuterium, being denser than hydrogen, would naturally sink slowly to the core. So you probably would have "fits" of deuterium burning (which remixed the deuterium) as the star slowly burned up its deuterium.
It will be able to pick up absorption lines, as this thing does have an atmosphere.
That's what I meant, though again it depends on the density profile of the object. The core of the object is likely too dense to let anything pass through it. We don't know what the core of Jupiter is made of - this object is something like 50 times denser.
The core composition is the interesting part, unfortunately. For that we'd need to be there.
If it's defined as a "star that is no longer burning", though, this would qualify.
That's what a stellar remnant is, not a black dwarf. A white dwarf is also a star that's no longer burning - it's white because it's still hot. Black dwarves are white dwarves that have crystallized. There's a specific definition because there's a phase transition (crystallization) that they have to go through, so there's a clear dividing line between white dwarves and black dwarves.
I even seem to recall that there was a white dwarf at around 11 LY that we could study.
Sirius B. First white dwarf ever discovered. Problem is it's sitting right by Sirius A, which is *not* a white dwarf - it's a blue-white supergiant. That must've been a hell of a system when it was active... The nice thing about this system is the fact that it's a bare white dwarf. Plus it has an interesting companion. Bonus.
That would let us image stellar atmospheres
We actually already can image stellar atmospheres. Only big stars, but stellar atmospheres nonetheless.
Here's an example. I used Betelgeuse because I think it was the first and only star for a while. I think there've been more by now...
Since it's a binary system, we'll assume that the two are cosmologically the same age, meaning that whatever generation they are, we're looking at roughly the same elemental mixture at birth (ignition), which we should be able to get from the dwarf's (vampire's) stellar spectra.
They're not the same mass, though. And since the white dwarf companion is - well - a white dwarf, it obviously was far more massive. It burned out first, for one.
A white dwarf's elemental composition, moreover, is not a good indicator of its original composition - just of its mass. It's a stellar core, after all - it's almost all carbon, with heavier elements inside in shells that again, depend on the mass of the star, and very little on its elemental origin.
I'll further posit that as the vamp star went through the nova phase, between 30 and 50 percent of the expelled mass would have been absorbed by the donor star (they're that close), but this would have been mostly composed of the lighter elements.
Yah - but the mass came *from* the donor star originally! It basically gets back a fraction of what it gave (although much less than 30%, I imagine - the shell is ejected with extremely high velocities. Fusion's powerful, after all).
However, remember that as the vamp absorbs matter (mass), it's gravitational attraction increases.
Not significantly. The amount of matter accreted that actually *stays* on a white dwarf is quite low. You need heavier elements (not H, He) to do that, and that's a tiny fraction of what it accretes (since it primarily accretes H). That's why it takes so long for Type Ia supernovae to occur, which is good - it allows the planetary nebula to be far from the star, so we can observe the supernova directly.
I'm still wondering what made the process stop.
So are astronomers. Most likely it's simply the fact that the other star is too dense - without fusion, the star would contract, and become more dense, though the lighter layers would separate, and continue to be accreted by the white dwarf.
Eventually, however, the starved star will fall into the white dwarf. Which will produce a *big* nova (but just a nova - not enough mass for a Type I supernova) and a slightly larger white dwarf.
I can't see how this is a revalation, more of just finally finding something of the right size.
It's the same size as a brown dwarf. The problem was that no one had found anything that's the same size as a brown dwarf, but not a brown dwarf (i.e., an object condensed from a nebula/disk but not large enough to complete the pp-chain at its core).
Things are classified typically by mass and composition. Almost everything falls into certain classes by those rules (stars, brown dwarves, white dwarves, planets, neutron stars, black holes, etc.). This falls well outside of any previous category of object. It's way interesting, too - its composition might reveal a lot about plasma physics and the interior structure of stars.
Thus, the star should have used these up very early in its life.
:) "Bulemic star" would probably be too non-politically correct.
Deuterium and tritium are byproducts of the pp chain - the star constantly regenerates them.
Once the pp chain stops, deuterium burning will continue for a while (stars are *big*, after all) but would, eventually, stop.
Spectrography might be able to detect the relative ratios of deuterium, etc. in the object, but not likely - its core is still quite dense, and there's little light being generated from there.
Pretty broad category, so probably not specific enough. Also tends to refer to things like planetary nebula and not stars (we haven't seen anything star-like that's been around long enough to cool down past "white dwarf" levels).
Stellar remnants are a broad class which encompasses anything left after a star has left the main sequence (planetary nebula, black hole, white dwarf, neutron star, etc.). This *is* a stellar remnant, though it doesn't have any classification within the stellar remnant class. Planetary nebulae are actually former stars. The former star is sitting at the center of the nebula.
This kind of object really does need a new classification - it's a new way for a star to die. I vote for "starved star", though it's not like my vote means anything.
The problem in naming is that mass doesn't define everything - composition is the other issue. A brown dwarf has the composition of the protoplanetary disk, slightly modified by fusion (lower concentration of D, higher concentrations of products of D fusion). A black dwarf is an almost entirely pure carbon diamond.
This object certainly is not a black dwarf - it's not a degenerate object, for one. It's also certainly not a brown dwarf - compositionally, it's totally different.
Keep in mind that this star was probably burning on the main sequence - burning, probably quite actively, for billions of years alongside its "partner" star. Virtually all of its internal composition probably bears little resemblance to the protoplanetary disk - it's been heavily changed by fusion and by virtue of having been *plasma* for that long.
What amazes me is that it's 300 light years away. 300 ly! That's virtually in our backyard! Jeez, if someone ever develops faster-than-light travel, this would be one of my first stops for astrophysics. In all seriousness, though, it'd be on my top list for observations when the next class of optical telescopes develop. A white dwarf, and a star frozen in development. And only 300 ly away.
Makes me wonder how many more of these they'll find.
MACHO.
MACHO, as you noted, means "massive compact halo object". This object isn't in the galactic halo. Therefore it's not a MACHO.
If you aren't informed enough by theories of time and space, don't say they don't exist.
Trust me, I know quite a bit about general relativity. I know that GR doesn't forbid closed timelike loops - but I also know that any solution involving closed timelike loops also must involve matter of exotic type, or objects where GR may break down (like black holes, etc.).
But it's naive to say that time travel might be possible with enough energy. Time travel, if it exists, will require significantly more than just energy.
And besides, like I said in a different post: jeez, who cares about time travel? Time travel implies the existence of faster-than-light travel (because... time travel *is* faster than light travel). I'd much rather faster-than-light travel exists - but right now, any physicist who knows enough about the situation would have a very healthy amount of skepticism. And if they don't, they're the ones who are on a high horse, not me.
as evidenced by the mongoose
Best story about mongoose being introduced into Hawaii - they were introduced to control the rat population.
One problem: rats are nocturnal (night-dwellers). Mongoose (at least the kind introduced to Hawaii) are diurnal (day-dwellers). The two species barely ever saw each other.
Yah, humans are smart.
Could the dwarf star absorb enough mass that fusion could start again? That would be awesome!
This is what novae are (not supernovae, which are different). When a white dwarf star accretes matter, it builds up on its outer shell. Since the white dwarf is incredibly dense, its gravity is incredibly strong, so the layer of matter (hydrogen) is incredibly hot. Eventually the density of hydrogen grows enough that fusion can occur again, and it does - and the star burns off (very quickly - ~few days) what took it several years to build up.
This causes a white dwarf to go from barely visible to extremely bright. In the night sky, it looks like a new star comes out of nowhere, then disappears - hence the word "nova", meaning 'new'.
If there's no nuclear fusion in its core, it's not a star.
Actually, this object is incredibly interesting. Composition-wise, it's a star frozen in time, and without all the nasty chemical-changing properties of nuclear fusion going on. There's a lot that could be learned from objects like that.
I have to admit, the original parent isn't being a complete lunatic on this one ... except, for this, you have to accept that cosmic strings can exist, and that general relativity is valid in that regime.
There are plenty of theoretical possibilities for time travel within GR, but none of them are really tractable.
One of the big problems is the fact that people have basically ended up playing with odd metrics in GR, coming up with bizarre geometries, and then finding out that the matter requirements to generate such a metric are very weird, and usually involve weird matter (like "negative energy density" matter). In your case, it's slightly different - the author started with weird matter (cosmic strings) and said "hey, weird stuff can come from that."
The problem is that I can't imagine real physicists believing that said "weird matter" is actually real at this point. Many of them might *hope* that it's real (hey, it'd be fun) but if you look at it objectively, the odds are definitely against it.
Don't get me wrong, time travel would be nice (well - actually, faster than light travel would be nice, and time travel is automatically faster than light travel) but there are no 'clear cut' "this must be possible" cases in physics yet. Any physicist who's being honest to himself would have to say that it's not likely.
Physicists don't drink the kool-aid on global warming. If you can prove that global warming is happening, then that is one thing. Trying to prove it is a bad thing is something else.
... so we're going to keep studying it (while continuing to dump CO2) and if it turns out that it was bad... then we'll stop it". This is insane. It's a very dangerous, very stupid experiment we're playing with by burning huge amounts of fossil fuels.
Um. Huh? Physicists are smart enough to know that carbon dioxide is a greenhouse gas, and that the Earth has a limited capacity to absorb it. Long term temperature trends show pretty clearly that the Earth is warming up. Much of it may be due to orbital eccentricity drift, but the problem is that CO2 levels are spiking dramatically (due to human activity) as well. This hasn't happened in any period of Earth's history that we can study.
Physicists would also be smart enough to know that the question isn't whether or not global warming is happening (it clearly is - the top five warmest years on record have happened since 1997, and if you look at the average global temperature, it's clearly going up) but whether or not human activity is causing it. And the problem with this is that we don't know enough about Earth to say it. We don't have a "control Earth". We know that humans are dumping huge amounts of CO2 into the atmosphere - far more than natural causes. We don't know what that will do. Any physicist worth his or her salt would know that this is, to quote a paleoclimatologist from Ohio State, "is a dangerous, uncontrolled experiment."
Bush is saying "well... we don't know what dumping huge amounts of CO2 is going to do
If there's one thing Physicists love to talk about it is energy. No one understands what energy is better than physicists. Energy is the end-all idol they worship, if they worship any idol at all. How do we exploit the energy out there? How do we get more and more of it delivered to the masses? If it were up to physicists, we would be doubling our energy production every ten years. There are so many useful things you can do if only you had enough energy! Even time travel is possible with enough energy!
What in the heck are you talking about?? Physicists would also know that any energy you produce has to go somewhere. And unless we start moving off this planet (which is one thing where Bush is correct - if he wasn't saying it just to be politically correct, as is evidenced by the fact that he didn't back it up in NASA's budget) that energy is going to be dumped somewhere on Earth. I could probably do a back of the envelope calculation figuring out how long it would take to incinerate Earth if our energy production doubled every ten years, but it's not worth the effort. Given that it's exponential growth, though, that number would be well less than probably 100-200 years.
And I really, really challenge you to find a real physicist who honestly believes that time travel is possible with enough energy.
Bush is willing to shovel the money they need into their labs.
News to all of the physicists I know. Well, those that aren't working on weapons programs.
(at the expense of matter in the universe, of course)
:)
And several conservation laws of physics, as well.
That being said, antimatter may just be a battery, but it is the best possible batter known to very, very basic physics (i.e. it's very unlikely to find a better one). Antimatter would be a very viable fuel for a lightweight probe to other star systems. A few have been proposed - I don't think anyone's taken them seriously, though. (AimSTAR is the one I knew of from a professor at Penn State, though it was definitely a pipe dream.)
No - because in one case, you're attacking the argument, and in another case, you're attacking the person. You need to actually be attacking the person for it to be a real ad hominem attack (which means against the person - not against the argument).
Claiming that an argument is likely to be untrue because it contains logical fallacies is simply true - if an argument has X points, and (X-1) are actually logical fallacies, then it has only 1 point which is a valid point in the argument. If the opposition has X points, of which only 1 is a logical fallacy, then it has (X-1) points which are valid points in the argument. Assuming X is larger than 2, then the argument with fewer logical fallacies is likely to be correct.
One overzealous judge could in fact slow down the process such that we have another 9-11-type calamity on our hands.
If the authorities had clear-cut proof - or even strong belief - of an imminent danger, they could "just act" - there are provisions in the legal system to protect them in those cases.
If they go before a judge, they don't have a strong belief that the danger is real. It's just a suspicion, and that's what the legal system is for.
Hindsight is perfect - we can always look back and say "they should've noticed this", or "this judge held things up so that they couldn't do this". But we will always be able to do this -regardless of how much we curtail our freedom, after something happens, we will always find someone to blame!
Typically, only 51% to 60% of the population in a given area shares his beliefs. So, the other 40% to 49% simply don't exist? Under Winner-Takes-All, they certainly aren't represented at all.
If those 40-49% really felt strongly about it, they could push their state government to change it. State governments tend to favor minorities (as does the federal government).
As I said, it's certainly possible that those states would prefer to have the Winner Takes All system - because it gives their state a larger voice.
In other words, the 40-49% are happy because they knew if they got another 2-10% of the vote, they'd get all of the electoral votes, not just some.
As Charles Dodgson (Lewis Carroll) discovered, there is no way to make voting fair (all the other voting methods - instant runoff, and the various Condorcet schemes - have weaknesses as well). The best way is to make sure that everyone knows the rules.
368000 feet is 112 km, not 102 km.
The first flight was 338,000 feet. This one was 30,000 feet (or ~10 km) higher.
They made this one far easier than the one before.
That's a minor form of taxation without representation.
Montana doesn't provide a fraction of a President. They vote for one.
They don't have any control over how those taxes are spent. They have an equal say in who decides how the government's laws are executed, but that's because the state bears similar risk with California. They have a complicated say in how those taxes are spent (via Congress).
Keep in mind that each state is a semiautonomous entity with its own laws, police, and bureaucracy. If you think about it in terms of costs, while Ohio has a population of 10 million, and New York has a population of 20 million, New York's operating costs are likely not twice that of Ohio, because the bureaucracy itself has an initial overhead cost, and then some scaling cost with population.
Of course, that's exactly what the Electoral College works as - an initial "overhead vote" of 2 people, and then a scaling cost with population (1 vote per so many people, with a minimum of 1 vote).
The only way to make the Electoral College consistent with the way the rest of the US works would be to abolish the existence of states entirely, which is counter to what the US was founded upon.
"Power in proportion to your population" is somewhat different from "completely ignore"
If everyone in California thought independently, I'd agree with you.
However, the simple fact that distinct mindsets exist in certain areas (why does Bush always win certain states? because the population in that area has concerns/beliefs that mirror his. The area drives the mindset) indicates that this isn't true.
followed by a national amendment to impose one allocation regime on all states
What if one community doesn't want to have that kind of voting? What if people want to live in California because California is a "winner take all" kind of state?
Funny thing is that the Electoral College system creates tyranny of the majority- within each state.
Depends on how the state wants to distribute its votes. The Constitution leaves that open to the states to decide.
It's less worrying to have state's decisions be driven by the majority than it is to have the country's decisions be driven by the majority. States are at least geographically close. One can't expect the worries of the population of Maine to correspond with the worries of the population of Hawaii, but it's reasonable to expect the concerns of the population of San Francisco to correspond to the concerns of the population of Los Angeles.
Let's use Texas as an example (although something similar happens in most states). There are a majority of Republicans and a minority of Democrats. When they vote for President, however, ALL the electoral votes go to Bush, instead of the Democrats sending their 30% to Kerry.
This is not a fault of the Electoral College. It is a fault of Texas, which decided that all of its electoral votes go to the winner of the popular vote. Other states do it differently. I won't argue if you try to say that states should do a better job at breaking up electoral votes, possibly by district. But that just redefines what "community" is, that's all.
If Iowa was really important, then the voters in California would see that (especially when they start paying those farmers for food).
In a perfect world, the sun would shine every day and I could pluck money from the money tree. And in that world, what you say would be true, and no one would have to worry about the tyranny of the majority, because the tyranny of the majority really would be the will of the people.
We don't live in a perfect world, and the tyranny of the majority is real.
PS. The use of the word "expense" in your post was completely nonsensical. In that sentence, "at the expense" should've been "in favor".
And you mean "complete nonsense", not "completely nonsensical", which is poor grammar.
True. But aside from the force of tradition, it's hard to defend why we need to enforce fairness amoung states, since states are not alive. Shouldn't we care more about actual people than states?
No.
For one, it avoids tyranny of the majority - something that's very, very difficult to deal with. For two, it allows a more even distribution of resources, and allows the country to utilize its resources efficiently.
The problem is pretty simple - people in communities tend to vote similarly, because they have the same concerns. People in California are less likely to be concerned about farmers in Iowa, for instance. Equal voting would mean that California would far, far outrank Iowa (more than it does). But that would also imply that Iowa's not important - and it is. Neglecting Iowa at the expense of California would mean that you'd essentially create a mecca of civilization, surrounded by an expanse of decaying towns.
This is exactly the case in a lot of other countries - specifically, Argentina, where Buenos Aires is akin to a first-world country, and everywhere else might as well be a third world country.
(Point of note: it only ensures fairness among states in that it gives two votes per state, and has a minimum number of representatives of one. Other than that, population reigns. Hence the reason why Wyoming ranks so high - because the population's nothing.)