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The Death of A Universe
ninthwave writes "The Guardian is running an article on research into the visible effects of entropy in the Universe. Alan Heavens of The University of Edinburgh did the research also posted at The Royal Astronomical Society with this article" I dunno - expansion, heat death - it all reminds me of a teacher who said "I'm not a premillenialist, postmillenialist - I'm a pan-millenialist, as in it's all going to pan out in the end." Update: 08/18 16:36 GMT by S : Headline fixed.
I was under the impression that "A Universe" would be more correct than "An Universe". "An" is meant to precede words beginning with a vowel sound, not a vowel letter.
OLPC Australia
Not 5 U.S. Billion, 5 U.K. Billion!
I think the current lingo (from what little I dig from a couple Stephen Hawking books) is that if there is more than one universe, then it can'tbe a universe, it has to be a multiverse.
So, my money's on multiverse.
The conclusions drawn by this article would appear to be fairly trivial at first. Basically energy can neither be created or destroyed and as the universe is expanding the overall energy density of the universe is faling. Less energy density means less luminosity.
I think, however that the scientists haven't accounted for the effects of hawking radiation, which is basically the energy given out when a piece of matter falls into a black hole. Hawking radiation is obtained from matter that is otherwise lost frrm the universe and as such does not obey the classical laws of thermodynamics. Because of this the amount of energy in the universe is actually increasing although the rate at which it is doing so is extremely slow. As mentioned by the article however the number of black holes is increasing (all matter is drawn together by gravity so in a long enough timescale it will eventually coalesce to form a black hole) and so the hawking radiation will increase. It is therefore likely that in a billion years from now, the sky will actually be brighter than it is now, not from stars (which as the article points out will have disappeared) but from a brilliant glow of hawking radiation.
All that glitters has a high refractive index.
Just to drive the point home, I found this at www.dictionary.com: In writing, the form a is used before a word beginning with a consonant sound, regardless of its spelling (a frog, a university). The form an is used before a word beginning with a vowel sound (an orange, an hour).
"we can't even account for 90%"
By 'we', you mean you and the publishers of various UFO magazines?
There are a number of good solid theories about the missing mass that have the small problem of observational scales to deal with, and given that black holes are still theoretical, although observed, the 90% figure you pulled out of your ass is considered a conservative estimate of stuff that don't glow.
"Figuring out the total heat or mass in the universe is still way beyond us."
Hence there being 90% of an unfigurable number being missing? There's a lot of waggly hand estimation and twocking great big error bars involved, but current estimates are pretty good.
"We don't yet have a theory of gravity that works for the galaxy, or fits with electromagnetic and nuclear forces."
No, we don't have a Grand Unified Theory, but we do have something that describes a galaxy. The problem is that there is a discrepancy between the rotational velocity of a galaxy compared with it's luminosity...dark matter is the sum of the difference.
Dark Matter can be rocks (that don't glow), dwarf stars, brown giants, WIMPS, MACHOs, biro world, enormous dyson spheres and/or compacted lumps of odd socks, or a mixture of all the above plus some oddities that we've not even thought of yet, but we're talking about big scales. I'll spare you the Douglas Adams definition of big, but it doesn't do to get complacent about the scale of the universe.
Oddly Draconis
Too cynical to live, too stubborn to die.
It was a good paper, at the time. Since it's publication; however, we have some fairly good evidence that the universe isn't going to slow down and compact in a "crunch" The evidence shows that the universe is actually accelerating outward. Additional evidence, seems to indicate that there isn't enough mass to reverse the acceleration. Current accepted theory is that the universe will continue to expand and thermodynamically "die"
What the "snapshots" of x billion years ago/light years away tell us is not just what that particular galaxy was like, but, we assume, other galaxies at the same age. (There's no reason to think otherwise.) So we can see a smooth evolution looking backwards the further away we focus. That gives us a perspective of not a hundred, but about 10 billion years.
Actually, since in the article they mentioned that the Big Bang occured 14 billion years ago, they are using "U.S. Billions" (10^9) and not "U.K. Billions" (10^12). That means that they predict the Sun will engulf Earth in 5*10^9 years (5 "U.S. Billion" Years).
Uttering logically derived and empirically supported truths to the disciples of the orthodox establishment.