How do we know how old the universe is, again?

[phucheneh]

Friday night and this is what I'm thinking about...

I've been reading/watching more about astronomy, cosmology and whatnot lately. This was spurred by the realization that, despite the History Channel's best efforts at convincing me otherwise, this stuff is not boring as shit.

Seriously...the History stuff...yeah, I know, that Raiden-looking Asian guy is really smart. Yeah, Morgan Freeman is good at narrating. But dudes...your shit is boring.

Anyhow, I've known about 'red shift,' the Hubble constant, and the stuff that's used to date astronomical events, the distance of stars, and whatnot. Doesn't seem like there's much room for argument in this area.

But I can't grasp how we can attempt to date the universe, or even provide evidence of the Big Bang. I mean, aren't there stars that can't be seen from Earth? If GRB 090423 is almost as old as the universe, purely figuring from how long its light takes to reach us...why do we not assume that there are things that are much further away? Even if we know the direction in which things are expanding (do we?), how can we have any idea of where the 'edge of the universe' is?

Not to mention...we don't know how fast the expansion of the universe is accelerating or when it started accelerating, no? There's also no known 'center' to the universe (or rather, prevailing theory is that it does not exist), despite the fact presumption that the universe began from a singular point...

Basically, there are a bunch of really smart people thinking about this kinda stuff, and most of the concepts boggle my mind...but it sure seems like we base an awful lot of things off of what are, at best, assumptions.

Also, general relativity, you are a bitch to understand. Perhaps that's my problem.

I will continue reading while someone from the ATOT Geniuses Club tries to figure out a way to explain the 'age of the universe' idea in fourth-grader terms.

I feel like even Wikipedia is being condescending.

 

[FallenHero]

Yeah, I've just found it best to leave the debate of the age of the universe to those people who can grasp concepts I cannot and understand math that is beyond anything I can imagine. Should someone introduce some evidence that suggests something else, rest assured you will hear the nerd rage on both sides until the debate is settled and new age is determined.

 

[phucheneh]

I mean, I [kind of] get cosmic background radiation, but I don't get how it can explain/confirm the things it is supposed to.

DAMN YOU NEIL DEGRASSE TYSON I WANT ANSWERS

 

[PowerEngineer]

I mean, I [kind of] get cosmic background radiation, but I don't get how it can explain/confirm the things it is supposed to.

DAMN YOU NEIL DEGRASSE TYSON I WANT ANSWERS

Answers (more or less) --> http://www.amazon.com/The-Fabric-Cos...s=brian+greene

 

[Newbian]

Count the rings of it.

 

[phucheneh]

Frankly it seems like the whole 'infinite expanding flat universe' thing is just part of a continuing evolution of theories that, unlike those about Earth and our solar system, cannot ever reach a definite conclusion.

Answers (more or less) --> http://www.amazon.com/The-Fabric-Cos...s=brian+greene

Is that just gonna make me want to punch the author, or is it written with the intent of non-physicists reading it?

 

[JulesMaximus]

It's 1000 years old. It's in the creationist bible yo.

 

[Sluggo]

Count the rings of it.

Or the candles on the cake.

It's really not that difficult. :hmm:

 

[disappoint]

The age of the universe is obtained by extrapolating backwards in time the expansion of the universe which we get from the red shift measurements.

The uncertainty is obtained from the cosmic MBR, or microwave background radiation.

 

[Silver Prime]

Ask, Stan lee.

 

[phucheneh]

Also: Based upon our understanding of galaxies, it seems logical to me that the universe would follow a similar model.

I think there's a superdupermassive black hole somewhere that marks the starting point of the Big Bang. And perhaps it, like the black holes at the center of galaxies, also used to be a star...which would be part of a bigger 'thing' with billions of universes...

And what made all those universes?

Jesus, obviously. PRAISE HIM!

Ok, no, not really any of that. But perhaps. :ninja:

 

[phucheneh]

The age of the universe is obtained by extrapolating backwards in time the expansion of the universe which we get from the red shift measurements.

The uncertainty is obtained from the cosmic MBR, or microwave background radiation.

But we don't know how fast these things are moving away from us, or if they've always moved at that speed or at least some mathematical function of said speed; we only how far away we presume them to be...even though they're moving away...

And the CMBR thing, in addition to being...weird...states the age of the universe during 'recombination,' yet I can find no mention of how the hell they came up with that number.

STEVEN HAWKING YOU DICK.

 

[Raizinman]

If you believe in religion and a god, you can claim the earth is 5000, 6000 or 50 billion. It doesn't matter. That is because if you believe in a god who created a universe, you must also beleive that its within his relm to created dated material. Perhaps he wanted to give a 6000 year old planet a tree with a decay rate showing 10 billion years old? You can apply any theory you want when you deal with religion.

 

[phucheneh]

If you believe in religion and a god, you can claim the earth is 5000, 6000 or 50 billion. It doesn't matter. That is because if you believe in a god who created a universe, you must also beleive that its within his relm to created dated material. Perhaps he wanted to give a 6000 year old planet a tree with a decay rate showing 10 billion years old? You can apply any theory you want when you deal with religion.

...I may not be a genius astrophysicist here, but I would think it seems clear that I'm talking about scientific theory based on empirical evidence.*

I'm not wondering if Jesus was running around giggling and planting dinosaur bones.

*Or more specifically, theory based on SOME empirical evidence, but seeming to have large holes filled by assumptions. While they may be the 'best' explanations in accordance with Occam's razor, they don't seem to be complete and concretely proven explanations, despite the fact that they are usually discussed as if they were solid facts. And they may very well be solid facts; I'm simply wondering if anyone can fill in the mentioned 'holes' with understandable explanations.

FILL MY HOLES, ATOT.

 

[BoomerD]

It's 1000 years old. It's in the creationist bible yo.

You were fapping to the National Geographic again instead of paying attention...weren't you?

The Bible explicitly dates the universe as being the same age as the Earth and just over 6000 years old. In fact, according to the Bible, all other celestial bodies are slightly younger than the Earth. At the moment the Earth was created there were no other planets, stars, comets, or other such bodies in the universe. None of these came into existence until the fourth day of the Creation Week (See: Genesis Chapter 1).

 

[StrangerGuy]

You were fapping to the National Geographic again instead of paying attention...weren't you?

I made the god who made the world...What? Prove it? He didn't have to give evidence so why should I?

 

[disappoint]

But we don't know how fast these things are moving away from us...

Why not? You do understand the concept of redshift right? We can measure the wavelength. We can also measure if the redshift itself changes over time.

 

[olds]

Ask, Stan lee.

Harvey

 

[randomrogue]

I think the scope of your questions is a bit beyond answering as a forum post. Really you need to read a lot of books and/or take some courses.

If you're really interested in this read up a bit on wikipedia on stuff like Hubble's Law and then hit the library and your local university. The problem you're going to genuinely have though is either you have to read a layman's version of this stuff that doesn't explain much of anything or you have to build up a foundation from the bottom up and learn a lot of math, physics, and astronomy.

 

[BladeVenom]

96% of the universe is made out of dark matter and dark energy, so at most we understand 4% of it.

 

[waggy]

96% of the universe is made out of dark matter and dark energy, so at most we understand 4% of it.

exactly. I think we just starting to discover the tip of the iceberg. there is far far more to learn.

it wouldn't surprise me to find the age of the universe is far older then suspected.

 

[mikeymikec]

96% of the universe is made out of dark matter and dark energy, so at most we understand 4% of it.

The universe is also made up of a certain amount of beetles.

 

[silverpig]

There are good answers to all of your questions, and I can give you most, but a full explanation would take too long. I'll try to make it simple so you can get the gist of it, and then you can google for further info.

There are several ways to get the age of the universe and they all agree with each other. One way is to use the cooling curves of white dwarf stars. If you ask what types of stars should be made in what proportions in the very early universe, part of your answer includes stars that are a special type of white dwarf right now. They will have lived their lives, blown off their outer shells, and have sat as super hot white balls of mostly carbon, that produce no new energy via fusion and just cool via radiation. You can identify them from their particular chemical makeup. You can also compute their cooling curves and measure their temperature. You can thus tell when they were made. If you want to read more about it, the prof who did this work is Harvey Richer. If you google his name and white dwarf cooling curves, you'll get some more material.

The main way to calculate the universe's age came from WMAP. In the early universe, everything was so hot and dense that there was no "space" as we know it today. There was "stuff" everywhere, and it was very hot, like the surface of the sun. The universe was a plasma, and plasmas aren't transparent. Everything was roughly at the same temperature and density (special caveat for later here), and thus as the universe expanded and cooled, the atoms everywhere recombined from a plasma into a hot gas at pretty much the same time. Gas is transparent to light, and so this wave of radiation started to permeate the universe. As the universe expanded, it stretched the waves of radiation out, cooling it. We know the temperature of the plasma back at the time of recombination from experiments on earth. We know the temperature of the radiation now from WMAP measurements. We can thus compute the distance/time it travelled to get the age of the universe.

We do know how fast the universe is expanding, and can measure it using redshifts. We can also tell how fast the expansion is accelerating from supernovae.

Here is a great FAQ site written by one of my old profs.

 

[darkxshade]

From what I've been led to believe, the universe expands as a whole, not just the edge expanding out. So basically over a long enough time period, the distance between our star and another star becomes greater. If that's true then it shouldn't be that difficult to calculate the rate of expansion and knowing the rate of expansion, one could also take that into calculating the actual size of the universe using other variables.

 

[sdifox]

Just go by the Bible.