How Do We Know the Timeline of the Universe?

StartsWithABang writes The history of the Universe happened in a well-known order: inflation ends, matter wins out over antimatter, the electroweak symmetry breaks, antimatter annihilates away, atomic nuclei form, then neutral atoms, stars, galaxies, and eventually us. But scientists and science magazines often publish timelines of the Universe with incredibly precise times describing when these various events occur. Here's how we arrive at those values, along with the rarely-publicized uncertainties.

Comments

We Really Don't

[TrollstonButterbeans]

"The history of the Universe happened in a well-known order: inflation ends, matter wins out over antimatter, the electroweak symmetry breaks, antimatter annihilates away, atomic nuclei form, then neutral atoms, stars, galaxies"

This is the comic book version of what happened.

We do not know that it happened in that manner. This is the popular version of what our current guesswork is and no more.

It should not be taken as "canon" or "real" any more than 2001 The Space Odyssey intro with apes inventing the use of bones as tools.

Because "science" --- the one with hypothesis, testing, reproduction of results is different than the speculation one --- which is very often quite wrong. If you want a recent example, there were many theories about the surface of Titan before we landed a probe there. They were quite wrong. So were a great many of the prevaling theories about Mars before we send probes there.

Early Universe ideas? Not fact. Not "well-known". Guesses.

Humans have made bad models from guesswork fit perfectly in the past, there were very orderly models of the geocentric model of the universe that accounted for the movement of Venus and Jupiter, etc quite well. http://en.wikipedia.org/wiki/G...

Re:We Really Don't

[jandersen]

This is the comic book version of what happened.

Well, it seems to be simply a high-school essay with glossy graphics; what did you expect? It doesn't look like Stephen Hawking's style, or even Brian Cox' - it's just some guy that's mighty pleased with his ability to make his website look like an issue of the Hello magazine and who's out to attract traffic to his site, that's all.

Because "science" --- the one with hypothesis, testing, reproduction of results is different than the speculation one --- which is very often quite wrong.

Well, in a sense we know that science is ALWAYS wrong - we propose a theory, and if its predictions survive comprehensive testing, it is accepted as being not far off the mark, but we know that is it not the final truth. The scientific method has arisen on this background as a way to make the discrepancy between theory and reality ever smaller.

Re:We Really Don't

[stjobe]

Early Universe ideas? Not fact. Not "well-known". Guesses.

That's... really selling science - and the scientific method - way short.

It's not "guesses", it's hypotheses, which are by their nature our best explanations of something given our current understanding of how those things work.

Calling these "guesses" reduces all the science that's actually going on and puts it on the same level as Joe Schmoe's wild-ass guessing on subjects he's not familiar with.

There is a world of difference between Joe guessing what happened in the early days of the universe and a scientist that has devoted several years of his life studying the matter putting forth a hypothesis of what happened.

Please don't paint these as the same thing, it's just doing the anti-science folk a service, and the rest of us a disservice.

Re:We Really Don't

[Anonymous Coward]

It really doesn't.

In which field? In cosmology? It sure does, cosmology is mostly wild guessing based on unfounded assumptions, that is, more guesses. In astrophysics? It sure does and then the guessing is beyond ridiculous, e.g. the Schwarzschild metric is a 'solution' of the Einstein tensor with mass basically set equal to zero, and somehow black holes that have non-zero mass fall out of it. In quantum mechanics? It is even worse, the models there are just descriptions of accelerator observations with a bunch of meaningless constants thrown in for good measure.

"Aliens did it" is at least falsifiable, if one is willing to chance a shot and dig around Area 51. And, incidentally, does make much more sense than the crap about the "timeline of the universe".

Re:We Really Don't

[Ol Olsoc]

The thing is our knowledge of the universe is so infinitesimally small that really it would be far fairer to call it a guess than a Hypothesis.

How do you know it is "infinitesimally small"?

That's sound bite cosmology. We don't ever know what we don't know.

The idea that there are certain types of stars that have certain compositions, and certain sizes and will likely have a lifespan of a certain number of years is a theory that has worked pretty well. We add to it when we find something that doesn't quite fit, and we modify to it as needed. Wanna see scientists get excited? When something doesn't fit, and they have to go back to figure out why. That's a happy scientist. Wouldn't be a happy politician or theologian though

But we do know some things about the universe. We'll never know it all, thank goodness, but a lot of physics pieces are falling into place.

Re:Bullshit

[Anonymous Coward]

I know I'm probably feeding the trolls here but...

Fine. I'm a post-doctoral research associate working on inflationary model fitting comparing anisotropies in the power spectrum with the anisotropies of galaxy distribution, with a side interest in the formation of stars at redshifts of about 5. In my time here I've done a host of jobs from outreach to 14-18 year olds, fundamental research, presentation to international conferences. And I've also cleaned the toilets twice, so yeah, I guess janitor could be on my CV too, if you care about that kind of thing (our janitors, for the record, are actually remarkably nice people, far more cheerful that I would be if I had their job, but I guess they only deal with literal shit that you can flush away, not the metaphorical shit that morons post on the internet).

The link to XKCD, if you know what you're talking about (which I strongly suspect that you don't) is a fit of a black body spectrum to the CMB. The point is that the data matches to such an amazing degree. The whole point of that comic is to state that our models work. They work incredibly well, far better in fact, than most of us would have thought when we first posited them.

The other links were just the beginnings of what is a very long list of ways we've tested our models against reality. I'm not your google guide - look them up yourself. What you'll find is that we see across a host of observations from different teams, different equipment, different phenomena covered that the predictions line up with observations to a very very high degree. The final result, as posited by the webcomic you so like to deride, is the tag line to that comic.

It works, bitches.

Re:We don't

[disposable60]

What if it was an empty void that suffered a spontaneous mass appearance.

And somehow that's not a big bang?

Re:Bullshit

[Anonymous Coward]

Welcome to all of science. If the theory doesn't match data, then you need a new theory. If you make a new theory, you make sure it matches existing data.