9k views

Why is the observable universe so big?

The observable universe is approximately 13.7 billion years old. But yet it is 80 billion light years across. Isn't this a contradiction?
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How can the diameter of the universe be so big, if nothing can go faster than light? [duplicate]

The following are facts of the prevailing cosmological model. The age of the universe is about 13.772 billion years. Nothing with mass can exceed the speed of light. The diameter of the observable ...
4k views

Size of the Observable Universe [duplicate]

I wanted to know what the observable universe is so I was thinking and I thought, it must be age of the universe times 2. Well I was wrong. I found on one website that it is 46B LY across in each ...
681 views

Speed of light and current dimensions of the universe [duplicate]

I've seen several documentaries explaining that the diameter of the universe is currently estimated at over 90 billion light-years. And which that - in the face of the age of the universe being about ...
91 views

How is observable universe so big if the universe is so young? [duplicate]

The diameter of observable universe is 93 billion light years but the age of universe is only estimated to be 14 billion years. So how does light have 46.5 billion years to travel from the boundary of ...
93 views

Why is the radius of the universe larger than? [duplicate]

It's always been in the back of my head that the Universe is 13.8~ billion years old and that the Observable Universe is 46~ billion light years in radius. How is this so? It would logically be only ...
23k views

Why does space expansion not expand matter?

I have looked at other questions on this site (e.g. "why does space expansion affect matter") but can't find the answer I am looking for. So here is my question: One often hears talk of space ...
3k views

Why haven't we seen the big bang?

The Andromeda galaxy is 2,538,000 light years away, so if we view Andromeda from a telescope, we see Andromeda how it was 2,538,000 years ago. Now the diameter of the visible universe is 92 billion ...
3k views

How is it possible for astronomers to see something 13B light years away?

In a NPR News story from a few years back: "A gamma-ray burst from about 13 billion light years away has become the most distant object in the known universe." I'm a layman when it comes to ...
974 views

Can the distance of a quasar be determined accurately?

As noted in How can a quasar be 29 billion light-years away from Earth if Big Bang happened only 13.8 billion years ago?, the wiki about quasars still contains the following misleading sentence: "...
2k views

How far has a 13.7 billion year old photon travelled

I've read that the size of the observable Universe is thought to be around ~46 billion light years, and that the light we see from the most distant galaxies were emitted ~13.7 billion years ago as a ...
1k views

Galaxies moving away at the speed of light

As an arts student, I really find those cosmological questions hard to understand and hence come here to seek your kind help. The Hubble constant $H_0$ is estimated to be about 65 km/s/Mpc, where 1 ...
601 views

How does gravitation propagate along curved spacetime?

In this wikipedia article it is described how a beam of light, with its locally constant speed, can travel "faster than light". That is to say it travels a distance, which, from a special relativistic ...