Expansion of the Universe

Brian G Turner

Brian G Turner

Fantasist & Futurist
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What do people here really think about the concept of Dark Energy and the accelerated expansion of the universe?

Without getting into another rant ( ;) ) I'll list my thinking and why I'm surprised the whole concept has gained such credibility:

Two people do some measurements of Type 1A supernovae.

- the assumption is that the process is fully understood - a binary system involving a white dwarf, which undergoes CO2 and O2 fusion at a certain critical mass.

The supernovae don't measure so bright.

Logically, you'd think the conclusion would be that the assumptions involved in the conjectured process are flawed.

But, no - instead it's obviously one of the most fundamental properties of the universe itself that must be at fault, even though there's no theoretical position to justify the presumed fault.

Yes, it is a possibility - but surely not the simplest answer.

I just cannot see the immediate justification in the logic involved in the conclusion - nor the overwhleming acceptance of the idea in the mainstream press.

Yes, it's a theory - but I really would wager that this is a blind goose chase, soon to have the lid shut on it.
 
Zero Point Energy

You're neglecting the fact that this theory incorperates the idea of zero-point energy, which has actually been obeserved in the laboratory. So it is hardly as though they don't have other evidence that this phenomenon exists.

The idea that the expansion of the universe might be accelerating hasn't anything to do with fundamental constants, either. The evidence suggests that the expansion of the universe might be accelerating rather than decelerating, and there happens to be an observed physical phenonmenon that would account for this observation.

Science moves forward. Perhaps it will turn out that current theories are incorrect, but for the time being zero-point energy has the preponderance of the evidence for it and no evidence against. But of course, the pool of evidence is still quite small.
 
I guess the whole "expansion of the universe" is such a fundamental issue to cosmology, that any theory that uses experimental data to address it is going to be highly regarded. Somehow I figure it's far too early days yet for that elusive "correct" solution though.
 
The expansion of the universe isn't a calculated fundamental constant, it is an observed phenomenon. Prior to the observations of an expanding universe, even Einstein modified his theory of relativity to account for a static universe (he later felt this was the stupidest thing he had ever done, and not a few physicists are inclined to agree).

The reason that we accept the idea that the universe is expanding is because of observations, not because of theory. The so called "Hubble Constant" is not the result of calculation, it is the result of numerous observations. If observation suggests that the Hubble Constant may be increasing rather than decreasing with time, then theories have to adapt, not the other way around.

Throwing out data that doesn't agree with your hypothesis is inconsistent with the scientific method...particularly when the hypothesis you are working on originated as an attempt to explain a data set.
 
Yes, that's why I referred to theory using experimental data. :)

I still find the conclusion of the observation of Type 1A supernovae more than a little ambitious - it would not have been the simplest explanation.

However, I suddenly find myself warming to the whole accelerating expansion concept. I believe there's a project in the works I think is called ESSENCE which aims to study these supernovae more extensively, with another with the acronym of SNAP in the planning to expand upon that work.
 
Don't get too attached. Who knows but that next year astro-physicists will decide the universe is really made of green cheese, and thus is slowly shrinking as the whey leaks out ;)
 
What was that theorey that the universe would end in a giant rip all about? Anyone know much about it? I've heard the theorey mentioned once or twice but never any real details. Something about the universe actually breaking up violently at a sub-atomic level. Anyone know anything?
 
Not sure about that - don't recall that idea.

I like the version where the universe continues expanding out - the Hyperbolic Universe, I believe it is. Which means that space is "saddle-shaped" rather than flat or spherical.

If you'd like to see some different "saddle-shaped" shapes then really do check out this site here:

http://www.indiana.edu/~minimal/gallery/index/catalog.html

and

http://www.indiana.edu/~minimal/gallery/index/index.html

Just think - when you look at those graphics, you could be viewing something of the fundamental reality of the universe. :)
 
Survivor . . .
Zero-point energy is a new one to me. Think you can explain it or point me to a site that does?

I read some about expansion: After the initial inflationary period, apparently space continued to expand on momentum. What I don't get is the idea of continued inflation. Has space continued to inflate, or started another inflationary period? For either case, what is (are) the suggested mechanism(s) for this observed phenomenon?
 
Actually, the whole expansion of the universe bit is one big hodge-podege and pot-pourri of desperate concepts - many of whih fail at some point, but fiddle with them a bit and it's like having a car - built from all different parts of vehicles - and held together entirely from bits of string. But that's the fun about cosmology - the sense of mystery and uncertainty of it all. As science should be. :)
 
I said:
Actually, the whole expansion of the universe bit is one big hodge-podege and pot-pourri of desperate concepts - many of whih fail at some point, but fiddle with them a bit and it's like having a car - built from all different parts of vehicles - and held together entirely from bits of string.
Click to expand...
Don't knock it. It's a living.
 
I've always thought the universe will one day stop expanding and then collapse, thus it will implode, creating another universe. I'll have to re-think my theory now, silly universe expansion...

PERCON
 
PERCON said:
I've always thought the universe will one day stop expanding and then collapse, thus it will implode, creating another universe. I'll have to re-think my theory now, silly universe expansion...

PERCON
Click to expand...
Yes, but modern cosmogonists speak of so called lack of mass in our expanding Universe to make such an imposion possible.
 
Stalker said:
Yes, but modern cosmogonists speak of so called lack of mass in our expanding Universe to make such an imposion possible.
Click to expand...

I've read up on dark matter and dark energy and the 'lack of mass' in the universe, the dark matter and dark energy theories plug the gaps. Although highly disputed theories they do explain a lot more about the universe and what's hidden from our current explanations of it.

Since my last visit to this site a few months ago, I saw something which showed that some planets in the distant galaxy display phases in their orbital motion where there's a kind of 'extra gravity' and planets orbit their star with varying speeds, the planets velocity graph was similar to a sin or cos graph, fluctuating up and down in a sinusoidal fashion.

This odd occurance was explained using dark energy which produces more gravity believe it or not. So if dark matter and dark energy fill in the gap and make up the 'lack of mass' in the universe, is the universe going to collapse once again like I said in my last post or are we going to be a part of an ever expanding universe? It's open for discussion and will remain so for many years to come...

PERCON
 
PERCON said:
...I saw something which showed that some planets in the distant galaxy display phases in their orbital motion where there's a kind of 'extra gravity' and planets orbit their star with varying speeds...
Click to expand...
Fluctuating gravitational 'strength'? New news to me, Percon. From observational data of extra galactic planets? Hmmm....

I'm sure there are other theories about some unknown possible variation on Newton/Einstein's laws for gravity that havent been infered from observational data, but so far dark energy and dark matter are the current (serious) options for causes of the observed discrepancy. Yeah... 'til they can figure out more about dark energy and dark matter or disprove it... we really cant say one way or the other...

(... and aint that a wonderful thing? ... not to know for sure!)
 
I took"some planets in the distant galaxy " to mean planets around stars distant in our galaxy. Not that it makes much difference as all extrasolar planets inferred (not "observed" so far) are in our local galactic arm, at a few tens of llightyears distance, hardly significant in universal terms. Maybe binary pairs of stars? Though neutron stars or black holes would seem a more probable explanation.

Of course dark matter theories do explain a lot more about the universe and what's hidden from our current explanations of it.. Dark matter theories say basically "if we want such and such a result, we have to have an 'x' factor, which is the difference between what we want, and what we can actually detect. Now we describe what characteristics this 'x' factor must have, postulate its existance, and specify that it will be detected in the future." This is called "circular reasoning" even when it's well concealed, and is practiced in many disciplines, and should be violently repressed.

Which doesn't mean dark matter doesn't exist; it's not a bad theory, but it's like the "steady state/continuous creation of matter" Hoyle theory (now in quiet retirement), a way of explaining away inconsistancies in present theories, rather than scrapping them and starting over.;)
 
Repress circular reasoning? To do that doesnt seem like it would allow us to sit in the 'think-tank' and grind those theories...

Aye, Hoyles theory had its half-day, but was never that popular. Not as popular or widespread as the current dark matter/energy theory, in terms of the number of educated cosmolgists debating it... This must have some slight bearing on where their current theories are going (or dying).

I think there are some aspects of string theory that come in handy for explaining possible scenarios for dark matter and dark energy... Please dont ask me to explain, because I might not know what I am talking about, hehe...

Science doesnt know as much as many non-scientists (possibly those tending towards being anti-science) as it appears. It can seem like a precarious balance, and thats one of the larger pictures I love about it... But sooo many things fit oh-so-snuggly! It can all tumble with a new theory that at the same time resurrects the whole thing again...
 
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