Ever accelerating universe?

General Questions
#1

Seen a number of other people with an interest in astrophysics on the debate board - so I thought I’d open a thread for a discussion. :wink:

Does anyone else here find the idea of an ever accelerating universe, powered by negative energy, grate against their intuition?

It all seems to have come about from a report around 1998, I think it was, with regards to measuring the distances to more distant supernovae. So far as I was concerned, the experiment involved was riddled with optimistic assumptions - yet the whole idea quickly became accepted without any seeming great challenge.

Recently there was an extensive mapping of background microwave radiation which purportedly supports the idea - but I’m wondering again what assumptions are involved.

It’s so surprising that the entire concept has been incorporated so quickly and easily into the foundations of mainstream physics. Personally speaking, this is one concept that I’d wager real money on for later dismissal. Anyone else bet on that?

#2

I don’t think there’s anything so surprising about mainstream science incorporating an idea quickly. A scientific theory is a model of some aspect of reality. If one hypothesis is more often supported by experiments than other hypotheses, it’s considered to be a good model based on the information available. If it’s the best model you’ve got, you run with it until you get new information that puts a different hypothesis in the top spot.

As I understand it, this new microwave background survey is just re-measuring some parameters to a greater degree of precision, and the relevant calculations point even more strongly to the idea of a forever-expanding universe (ending in a Big Chill instead of a Big Crunch).

Of course, any good scientist understands that the model is just a model, and if something happens to topple its superiority among its fellow hypotheses, then so be it. It happens all the time. Nobody’s pretending that their hypothesis is The Final Answer.

Does anyone else here find the idea of an ever accelerating universe, powered by negative energy, grate against their intuition?

Not really… what if there are lots of universes? Some of them might have enough mass to re-collapse after they stop expanding, and some will have enough energy to expand forever. Some might not have enough of anything to get going in the first place. It’s aesthetically pleasing to think of our universe as having a definitive beginning and end, a neat package with a bow around it, but if we’re part of a bigger picture there’s no reason why that should be.

#3

Has anyone been able to use “physics” and “intuition” in the same sentence since the 19th century?

#4

Sure, as long as they’re talking about classical mechanics.

#5

Indefatigable -

Thanks for the good answer. I guess I am simply surprised the concept was so easily integrated within the standard model. The longer it remains there the harder it will be to remove, now being a frame of reference for countless other experimental data.

Yes - but only if you are a visionary. :wink:

#6

To me this is a very important point. The Universe doesn’t give a flying flip what your intuition is. People who insist on physics making sense and being intuitively simple despite evidence to the contrary go on to write things like the Shadows model of Physics.

#7

It’s just a little more complicated than that. There are visionaries in physics who have constantly pushed the boundaries of knowledge.

Paradigms exist precisely because “the data supports them”. It takes people with insight - intuition - to stumble into new ways of framing concepts.

Scientific method is not about stumbling blindly through numbers. It’s about creating ideas to test through hypotheses, and that’s where the vision comes into the issue.

#8

What kind of visionaries did you have in mind? Einstein, for instance? The reason his idea of relativity caught on was not because it was visionary or enlightening per se, but because it fit the data better. Just what kind of improvement does “Nah, I don’t think there’s really a negative energy” offer?

#9

True - but it was less looking to expound upon alternatives, as much as stating general unease at how quickly the idea has been incorporated into cosmology - a field which those who work in appear to be becoming quite resigned to the general “fudge factor” being forced on it. At least, until movement can be made on the issue of unifying gravitational mechanics with the quantum world.

There are a lot of attempts to be visionary in cosmology at the moment - negative energy, superstrings, dark matter, are the most obvious examples of theories being developed. Whether they are intuitive or not is another issue entirely.

I was simply asking other people had reservations about the issue of negative energy. Perhaps this topic really would have been better posted in GD.