The Nature of the Universe

[elforcelf]

Flumphs are the rulers of the universe! Whaah ha!

 

[elforcelf]

Sorry,siliy mood today. I love science.

 

[fuindordm]

Double post

 

[fuindordm]

At the moment, I'm reading about the Big Rip theory and the suggestion that the universe not only keeps expanding but the expansion keeps accelerating until it's ripped apart. Impossible to prove any of these theories but they are interesting.

Well, proofs aren't entirely out of reach. But at this point they're more likely to come from high-energy physics experiments like the Large Hadron Collider at CERN than from astrophysics. One of the reasons we study astrophysics is that the various celestial bodies reach much higher energies than what we can produce on earth, and so have the potential to teach us a lot about the fundamental nature of matter and energy. At this point, however, we're talking about identifying the mechanism that creates vacuum energy, or discovering new particles and detecting them on an individual basis. That's what's needed to start proving or disproving some of the theories about the ultimate fate of the universe.

As for the Big Rip...was that from the Exit Mundi website? This isn't something standard cosmology predicts either; bound systems from galaxies to atoms don't get expanded along with space, and if the acceleration is due to a non-zero vacuum energy then its effects will only be felt in the vast reaches of vacuum--it will still be insignificant in any region where matter is of higher density. The whole point of vacuum energy is that its energy density is constant throughout space.

For bound systems to get ripped apart, you'd have to have the vacuum energy density evolving with time, probably along with other fundamental constants. In that case, yes it could happen. The time scale would be tens of billions of years at the very least--change in the fundamental constants is still controversial, which means that it's barely detectable over 13 billion years or so (the age of the universe). For the constants to drift enough to alter structures will therefore probably take at least another 13 Gy. We won't know though until we see a strong positive detection of evolution and can estimate the rate of change.

Ben

 

[Zappo]

Change of fundamental constants is indeed one of the "possibilities" in the exit mundi site. Change of fundamental constants allows for lots of spectacular ways to blow up the universe.

 

[Umbran]

Errr... his posting a "hey, guys, look at this!" link on a messageboard dedicated to D&D probably doesn't really fall under the aegis of science news reporting.

In the sense that it's not gong on the AP wire, you are correct. In the sense that science information is getting passed from person to person in a public broadcast, and some of it was inaccurate, you're incorrect.

The internet is the #1 place to get inaccurate science information. Just doing my small part to tidy the place up a bit.

I agree, but this is one of the most difficult things I've ever had to explain to non-scientists. It goes hand-in-hand with the question "If the universe is curved, what is it curving into?" WIthout recourse to differential geometry and number theory, I really don't know how to make the skeptical layperson comfortable with the idea of expanding, infinite, curved spaces.

Yeah and verily, this is true. Some things are difficult to grok in fullness without the mathematical background, which is a darned shame. This one, in particular, has been something I've been trying to figure out how to get across withotu the math for some time.

I ought to go back and review A Brief History of Time. Hawking does a really good job of explaining many things with no math whatsoever, and there are probably hints to be taken there.

 

[The_Universe]

All this trouble, and all you had to do is ask.

The Universe is sleepy. And when The Universe is sleepy, The Universe is grumpy.

 

[fuindordm]

All this trouble, and all you had to do is ask.

The Universe is sleepy. And when The Universe is sleepy, The Universe is grumpy.

So... are you inflating? Do you feel bloated?

Ben

 

[Darth K'Trava]

I agree, but this is one of the most difficult things I've ever had to explain to non-scientists. It goes hand-in-hand with the question "If the universe is curved, what is it curving into?" WIthout recourse to differential geometry and number theory, I really don't know how to make the skeptical layperson comfortable with the idea of expanding, infinite, curved spaces.

(Of course, the current cosmological model favors a flat universe.)

The question of what lies 'outside' is not one that can be answered easily when your cosmological theory doesn't include the concept, and you have no hope of ever observing it directly. It's not part of the standard model, but that doesn't prevent physicists from theorizing about it. This is another itch that the superstring/brane theories can scratch for us if our imaginations aren't satisfied with contemplating the observable.

Ben

I don't see how the universe can be "flat". There's no way it can be linear"; it'd have to have all three dimensions and quite possibly a fourth as well to encompass everything that exists within it. There's just too much mass to suggest otherwise and mass definitely isn't flat nor linear.

 

[Darth K'Trava]

All this trouble, and all you had to do is ask.

The Universe is sleepy. And when The Universe is sleepy, The Universe is grumpy.

I'd get grumpy too if I kept expanding at a constant rate that makes The Santa Clause seem cheesy.