I’m sorry Brother Rat. Those things were brought up in another thread [url=“http://boards.straightdope.com/sdmb/showthread.php?threadid=72348”] here I got my threads confused.
Well, that didn’t work out. Try clicking on this: http://boards.straightdope.com/sdmb/showthread.php?threadid=72348
Funny… I thought I’d already answered that one. Much though I like having three or four cosmology threads active at once, it can be a bit disorienting: What did I say, where?
You can use the average lifespan of a free neutron (about 15 minutes) as a time standard any time after neutrons came into existence (within the first few minutes, I think). Before then, even if nothing else, there’s always the Plack time, which is based on fundamental constants of Nature.
But what if the fundamental constants of nature were different at the very begining of the universe?
Some cosmologists believe that the speed of light was much faster? Everything is based around it so then doesn’t things like time change?
PerfectDark
Planck’s Time is really useful. It’s a good assumption that constants are indeed constants. At least there’s no data yet that says they change. So if you became some kind of being who could view things without interacting with them at all, you probably could use that to tell time if you went back that far.
Atoms came into being like this: Nuclear matter which means protons and neutrons, the absolute minimum for a Hydrogen atom came about, according to my copy of the Standard Model (1991) at just after 10[sup]-6[/sup]s. Atoms more complicated atoms then the simple 1 proton H developed at and about 1s.
Hmm, just reread your OP from the other thread and I’ll answer your question this way.
When a scientist wants to know how long it took from t=o till a certain important event occured after that. He assigns t=x, plugs in all the other data and solves for x. That’s how they know that the end of Electroweak Unification occured at 10[sup]-12[/sup]s. Not very satisfying is it?
Unfortunately we are stuck here on earth and as such we can only makes vague stabs at certain things. Somebody mentioned that at one point the universe looked younger then some of its stars. This wasn’t really a paradox, it just looked like one. Somebody’s measurements were just plain off. If I recall correctly I think they worked it out that the distances to the stars were off, hence the ages given to them were off.
Hopefully that new supercollider that they jsut finished and are working on getting on line will help us understand the subatomic particles better. And once we get that maybe we can finally get a Grand Unified Theory, and once we get that then our predictions at when things happened in the opaque universe will be even more precise.
It’s really not meaningful to talk about the really fundamental contants changing. If hbar, for instance, did change, then that change would in turn cause changes in any possible measuring device you could design, in just such a way that the measured value would be the same. You need some basis for comparison.