Talking about the Universe
- Thread starter Ziggy Stardust
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ParkCungHee
Deity
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Really? The crab?
Angst
Rambling and inconsistent
Ailedhoo
wonderer
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Ziggy Stardust
Absolutely Sane
Borachio
Way past lunacy
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I'm confused. How do you measure the Universe if you're inside it? And the only measuring sticks are things, like the speed of light, which are also inside the Universe itself.
So, how big is it? Is there anyway to tell?
Is it bigger than, say, a very big house? Because I've seen some very big houses (from the outside, naturally, I'm not going to pay to go in one, am I?). And they are BIG.
So, how big is it? Is there anyway to tell?
Is it bigger than, say, a very big house? Because I've seen some very big houses (from the outside, naturally, I'm not going to pay to go in one, am I?). And they are BIG.
warpus
In pork I trust
The observable Universe is about 96 billion light years across, I believe. Outside of that, we have no idea.
You're arguing against looking for unified theories.
E=mc^2 relates energy, mass, and the speed of light.
So maybe we can say that distance - a lightyear - can be related as:
(E/m)^1/2
Obviously, this doesn't really address your concerns. But within a framework where all forces, units, charges, and fields are unified*, things will only be described and defined in relation to each other, plus some constants.
*not there yet, but that's the grand work being attempted. QFT + GR = ToE
Borachio
Way past lunacy
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Well, see, if things are only defined in relation to each other, there's no reason to suppose we'll ever know how big the (known observable) Universe is. It could be x light years across, but that could mean anything. From some position outside the Universe (that is, from some other Universe) it might be as big as an egg cup or as small as a billion football stadia.
But I'm pretty sure that sort of statement is meaningless. Like, nonsensical. Like asking how many purples make up a right angle.
If the values aren't related to each other, then they have no meaning?
A light year is the distance light travels in a year. And that year part is important: In Relativity, you can equate distance with time. So anytime you wanted to measure distance you could measure time and the other way around. So the question would be: how much time is a light year, with the easy answer: a year!
And for time we have a lot of rulers we can use.
PlutonianEmpire
King of the Plutonian Empire
The universe is a vicious, life-sucking hell-hole from which there's no escape.
Cheer up. The heat death of the universe isn't slated until next Tuesday!
It IS big, and that's just the four dimensions that we perceive. There could be a bunch of extra dimensions, each adding size the same way a cube is bigger than a square.
It IS big. We can see about 13 billion light years each direction, but we think it has since expanded to something like 45 billion light years each way. And that's just our light bubble! Best estimates are that the 4D universe is at least 100 times bigger than our light bubble. I think thats means we have (at least) 1300 billion light year radius around us or room enough for (at least) a million light bubbles the same size as ours that would never touch.
There're currently enough stars in our galaxy to give ~30 to each person on the planet.
That's impressive.
5 It is like a bridegroom coming out of his chamber,
like a champion rejoicing to run his course.
6 It rises at one end of the heavens
and makes its circuit to the other;
nothing is deprived of its warmth.
It IS big. We can see about 13 billion light years each direction, but we think it has since expanded to something like 45 billion light years each way. And that's just our light bubble! Best estimates are that the 4D universe is at least 100 times bigger than our light bubble. I think thats means we have (at least) 1300 billion light year radius around us or room enough for (at least) a million light bubbles the same size as ours that would never touch.
There're currently enough stars in our galaxy to give ~30 to each person on the planet.
That's impressive.
4In the heavens God has pitched a tent for the sun.
5 It is like a bridegroom coming out of his chamber,
like a champion rejoicing to run his course.
6 It rises at one end of the heavens
and makes its circuit to the other;
nothing is deprived of its warmth.
dirtyparrot
Upholding Brannigan's Law
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I'm a little awestruck by how much is happening on the largest and smallest of scales.
