What will happen to the universe?

[Geronimo]

Originally posted by Blaupanzer


Urban Ranger was providing a very, very condensed version of Hawkings theory that the laws of physics, as we know them, came into being microseconds after the Big Bang. The "ball of energy" he referred to was the time before those few microseconds.

I will bow to your expertise on the lambda-CDM. However, as I understand it, it requires we postulate an item (dark energy) to exist that we can neither identify or detect, let alone test. Since science is all about testing, how does dark energy (including dark matter) differ from the belief in angels or the "aethyr" theories of the late 1890s.

The original question was about the end of the universe. The universe appears perfectly capable of going on to ultimate entropy without the need for or use of dark energy.

All proposed forms of dark matter that I've seen whether WIMPS or MACHOS or whatevers all had means of detection proposed as well. They are just tricky to detect.

Being tricky to detect is a world of difference from being impossible to detect. You wouldn't compare neutrinos to angels or "aethyr" would you?

Furthermore, the "aethyr" shouldn't be treated as being in the same category as angels because the "aethyr" was in fact testable.

[KrazyHorse]

Originally posted by Geronimo


Weren't the fundamental forces indistinguishable at those high energies? maybe that's what he meant?

That doesn't mean anything, though. Density fluctuations will persist unless wiped out by some sort of physical process.

Urban Ranger was providing a very, very condensed version of Hawkings theory that the laws of physics, as we know them, came into being microseconds after the Big Bang. The "ball of energy" he referred to was the time before those few microseconds.

You are talking about cosmology from 25 years ago. Inflationary cosmology makes nonsense of the notion of specifying a point in time for the "big bang"....

[Geronimo]

Originally posted by KrazyHorse


That doesn't mean anything, though. Density fluctuations will persist unless wiped out by some sort of physical process.

just to be clear. Saying that the fundamental forces are indistinguishable at high energies doesn't mean anything?

[lord of the mark]

"The concern that you might well be proven completely wrong a hundred years in the future can be brought up in all scientific investigations"


Yes, thats true. But few areas of human endeavour deal with such long durations of time. Its certain, for example that in ten thousand years of further work on climatology will give us a better view of global temperatute dynamics than we have today. But thats irrelevant to predictions of global climate in the next hundred years. Its likely that in 300 years economics will give us greater insight into world trade and financial flows than we have now - but THATS irrelevant to understanding the workings of globalization in the 21st century. Climatology will likely be dealing with different problems in 10000 years, and economics in 300 years.


But as far as the end of the universe, we are at the BIRTH of human investigation of the issue (again, assuming that human civilization doesnt crash). Which is good for you - youre at the beginning of something. But it makes most lay comment about the issue just seem silly to me.

[lord of the mark]

Originally posted by KrazyHorse

You are talking about cosmology from 25 years ago. Inflationary cosmology makes nonsense of the notion of specifying a point in time for the "big bang"....

my point.


old cosmology - 1981
new cosmology - 2006.

Galaxies discovered - 192x

heliocentric model of solar system accepted, 16xx

Universe to end, 2006 + x billion years. (x being well in excess of 1)

Will cosmology look less different in 2031, than it does today, from 1981? If not, then, given no practical apps in the next 25 years, why should a lay person pay attention to it, other than to the side impacts on the rest of physics that, I suppose, flow from it?

[Lancer]

Originally posted by KrazyHorse


Because odd coincidences bother us.

Why should they? Does this bother suggest you're concerned by a possible intelegent design?

KH, thanks for taking the time to answer all these questions.

[KrazyHorse]

Originally posted by Geronimo


just to be clear. Saying that the fundamental forces are indistinguishable at high energies doesn't mean anything?

I'm not saying that it doesn't mean anything period. I'm saying that it doesn't mean anything, in and of itself, when it comes to persistence of density fluctuations.

[KrazyHorse]

Originally posted by lord of the mark
"The concern that you might well be proven completely wrong a hundred years in the future can be brought up in all scientific investigations"


Yes, thats true. But few areas of human endeavour deal with such long durations of time. Its certain, for example that in ten thousand years of further work on climatology will give us a better view of global temperatute dynamics than we have today. But thats irrelevant to predictions of global climate in the next hundred years. Its likely that in 300 years economics will give us greater insight into world trade and financial flows than we have now - but THATS irrelevant to understanding the workings of globalization in the 21st century. Climatology will likely be dealing with different problems in 10000 years, and economics in 300 years.

And cosmology, if it still exists as a field in a thousand years, will likely be dealing with completely different questions. It could be that we have a good first approximation. Or it could be that we don't. The same is true in all those other fields.

If what you are trying to get at is that cosmology as a field is unable to study the evolution of the universe as it actually happens, then I agree with you wholeheartedly. You can watch a ball rolling down a hill many times. In cosmology, all we get is this integrated snapshot of everything which has happened along a particular line of sight since the beginning of the universe. Human timescales are so short that we can't watch this snapshot evolve in time, so there's a hell of a lot of work which has to be done to get any information out whatsoever, and there is a very delicate chain of inferences which need to happen in order to draw any conclusions whatsoever.

But as far as the end of the universe, we are at the BIRTH of human investigation of the issue (again, assuming that human civilization doesnt crash). Which is good for you - youre at the beginning of something. But it makes most lay comment about the issue just seem silly to me

I guarantee you that most of the lay comment seems a lot sillier to me than to you.

[KrazyHorse]

Originally posted by Lancer


Why should they? Does this bother suggest you're concerned by a possible intelegent design?

No, not for this odd coincidence.

If you want a much better example of us being concerned by the appearance of "intelligent design", then the you should ask about the fine-tuning vacuum energy problem .

I'm beginning to see what lotm meant by laypeople drawing metaphysical conclusions now. Lancer, some of our theories are wrong. Wildly wrong. There's no need to go any further than that for an explanation

[Lancer]

Well, certainly lotm was correct. Consider the dillemma of the average christian such as myself. The bible says something like (though not a straight up quote) 'you can see Him in His works', ie, the creation. Also, 'it is a buggered generation that seeketh after a sign'.

So, while we look for Him in the beauty of His works we let you sci guys seeketh after the sign. It makes for a nicer, less confusing day.



In my view the whole universe is designed to function without devine intervention because it's the most efficient way to design one. If you can build a car that doesn't need oil changing you will because who wants to change the oil? Another reason might be that we believers are not to be 'doubting Thomases', we're to live or die on faith, trust. If God shows up now and again with an oil pan and 8 quarts of Penzoil...

Anyway, I've heard of a few things that are interesting. On TV a geologist unable to explain why two different colored granite viens 'flowed' together. He had an example. A granite rock in which the above obviosly occured. However there was no condition under which granite stays granite and flows.

Though I don't base my faith on such stuff, it's kind of interesting and fun.

So, what's the deal with the vacuum?

[Geronimo]

I strongly doubt he'll deign to explain his point about fine-tuning vacuum energy problem in laymans terms

[Lancer]

Geronimo, are you up to the challenge?

[DaShi]

SOME say the world will end in fire,
Some say in ice.
From what I’ve tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To know that for destruction ice
Is also great
And would suffice.




This thread was driving me crazy without it.

[KrazyHorse]

Originally posted by Geronimo
I strongly doubt he'll deign to explain his point about fine-tuning vacuum energy problem in laymans terms

Simply put, it's that if there's any vacuum energy at all, naive high energy theories predict that its density should be ~10^120 times bigger than that measured by cosmology.

It's pretty easy to create a theory which predicts 0 vacuum energy, but to get a vacuum energy which is nonzero but tiny requires what's called "fine tuning" i.e. you have one enormous number, you subtract it from another enormous number and are left with a tiny number.

Fine tuning is bad, since there's no reason the numbers should cancel out almost but not completely.

[Geronimo]

Originally posted by KrazyHorse




Simply put, it's that if there's any vacuum energy at all, naive high energy theories predict that its density should be ~10^120 times bigger than that measured by cosmology.

It's pretty easy to create a theory which predicts 0 vacuum energy, but to get a vacuum energy which is nonzero but tiny requires what's called "fine tuning" i.e. you have one enormous number, you subtract it from another enormous number and are left with a tiny number.

Fine tuning is bad, since there's no reason the numbers should cancel out almost but not completely.

Didn't there used to be speculation that matter and antimatter were present in nearly equal amounts but not quite so that they canceled out almost but not completely? Or was that idea never really held?

I'm a little surprised it's so rare for things to almost but not quite cancel out.