How can we look at light 13 billion years old?

Question

If Hubble captures light that is 13 bn years old and the universe is approximately 14 bn years old, how come we can see it?

Wouldn't the universe be a maximum of 1 billion light years across when this light was created and it therefore would have gone past us 12 bn years ago? I thought that the speed of light is an absolute limit, so to repeat the obvious it would have been produced when the universe was 1bn years old, but 13 bn light years across (mimimum).

Please answer ASAP as I need to sleep.


Thanks.

PS No maths please.

Answer 1

The universe is not 13 bill. light years across - it is 13 billion (plus) light years away from un in Every direction.
When the light we see from the very far away (in space as well as time) left it's point of origin the universe Was much smaller, but it is consntantly expanding. As a result the light from those objects is only reaching us now.

Answer 2

Very good point. Are you sure about your numbers?
If there was a Big Bang 14 bn years ago and they knew where the center of the "Bang" was then the universe would have had to expand at just under 1/2 the speed of light (average speed till now) to be 13bn light years across. Ooooh that may be why. as the universe expands it slows down exponentially due to the attraction between planets. Therefore the light may actually be that old.
I think, but I am most likely wrong. I'll keep an eye on your question.

Answer 3

The entire universe was at where the big bang was so the light is still here, due to the fact that the universe is like the surface of the Earth, the light will continue to go on and eventually return to the same place. I mean, where do you except the light to go to? The fourth dimension? That's ridiculous, how can light escape to the fourth dimension? Think about this. You're walking on the Earth (imagine you can walk on water too), will you come to the edge of the Earth, no, because the surface of the Earth is wrapped around a sphere and there is no edge. Same with the universe, the 3 dimensional surface is wrapped around a 4 dimensional hypersphere. So there would be no such thing as the edge of the universe, just as there is no such thing as the edge of the surface of the Earth.

Answer 4

Okay look. Here's how it could be possible. I like the explantion from AJ and Firstd1mension. But I'm going to add to that. Some people speculate the at the time of the big bang, the universe expanded at a rate that was a bit faster than the speed of light. Now I'm going to include this. According to Einstein's Theorys, if you go faster than the speed of light, you phase out. Into another dimension. Now when the universe slowed down, in popped back to our dimension. But not all of it. Therefore we have the theory of multiverse. If we have a dimension that exists at extremely high velocities, then who's to say we don't have one that occurs at a dead stand still?

Answer 5

Short answer: via refraction and scattering of primordial background radiation.

When they say they're capturing light that is that old, they're not talking about a star or light from some identifiable object. They're talking about background radiation, which originates from when the universe cooled from plasma to gas around 300,000 years of age. Background radiation travels in straight lines, so the majority of it is far out beyond our reach on the fringes of the universe's expansion, as you envision it. However, there is also a percentage that has been reflected and scattered by a number of forces (gravitational bending from black holes and stars, reflection off solid objects, plasma scattering, etc), and there has been enough refraction over the past 13 billion years to create a vague background haze detectable in space. That is the light they are referring to.

Picture it this way... in the first 300,000 years, you had no light released because the universe was too hot and dense of a plasma to even allow light to escape. Then at 300,000 years, the expanding universe breaks into gas and space, and at its fringe you have a giant and brilliant ring of light travelling outward at the speed of light, following the edge of the expanding universe. The expansion horizon itself is also emitting radiation inwards towards the center of the universe. While the majority of the light is on the fringe, you have enough randomized scattering in the middle to have some of that old light still "hanging around" in the middle as a very light haze, randomly bouncing around the pinball machine that is the cosmos... only a miniscule shadow of its brilliant origins, but still detectable.

Answer 6

My 3 inf:

- Matter cannot be destroyed, so anything that was around at the big bang should still be around now.


- Even if the universe isn't big enough across, light doesn't necessarily take a straight path. Photons (ickle tiny weeny particles we see as "light" when they vibrate) are matter just like any other and have mass (weight), so they can be affected by gravity.

It's therefore perfectly possible that photons that old have been pinballing off planets and swerving round black holes for all time. (Wonder who's getting the high scores?)


- The higher reaches of theoretical physics require more and bigger leaps of faith and twisty interpretation than any major religion IMO... :P

Answer 7

Well you see math is the problem. Using your figures it's pretty impossible. Either your numbers are wrong, physics are wrong, or Hubble needs one heck of a calibration.

"I thought that the speed of light is an absolute limit"
no, it's a theoretical limit (like everything else). the idea is that in order to accelerate matter to the speed of light one would need more energy than exists in the universe- but physics has more loop holes than case law.

Answer 8

I watched a documentry on this a few days ago. Light travels weird. When you see a star in one state on earth thats actually looking back in time hundreds, thousands, millions, or even billions of years ago. Its hard to explain how, or why, its like that, it just is. Scientists say that that is partly how they learned more about space, from looking "back" in time through the starts. They said that is they can get a teliscope and enough light to be able to see very far back, that they can learn more about how life started, and when life started.

Answer 9

The answer to your question is easy: nobody can put an age to the universe if the universe is infinite. Eveybody agrees the universe is infinite. If the universe has lasted/will last forever, 13,14,15---billion years amount to microseconds. The more important question is how have scientists been able to calculate the age of light?

Answer 10

How did you get to the assumption that the universe is 1 billion light years across?