Thread: Tell me about this conundrum

So here we are right now, in this present moment of existence. Now what boggles my mind is this simple fact that when we look at the sky we are actually looking back in time. Supernova's, stars light, gamma ray bursts, all happening millions upon millions of years ago. Ok, I get that part, but what I don't understand is how that actually works.

Let's pretend a gamma ray burst happens in some far off place in the universe and it takes place very close to the time of the big bang. So that massive explosion happens in its time and then it travels for eon's through spacetime and reaches the observing lens of telescopes and astronomers eyes......now in this present moment. I mean if thats true then we can theoretically see the big bang to the exact point of its creation then right? Now that just blows my mind; seeing your own creation when you didn't exist, fucken amazing.

Unfortuantely we can't actually look back to the very point of the Big Bang, as there was a period of about 300,000 years after it in which the Universe was just a a super hot plasma of charged particles. As the universe expanded, it cooled and elements began to form. From these elementry particles of hydrogen and helium the first stars formed, which were total giants even compared to our largest stars today.



But it's still amazing all the same, even if we can't peer back in time to T=0.

What if the big bang explosion expanded way faster than the speed of light? Then, wouldn't all these calculations be false?

No, because the expansion IS faster than the speed of light.

But only because the fabric of space ITSELF is expanding outward. Even though the universe is only 13.7 billion years old, the observable universe is actually around 92 billion light years across. That might sound counter intuitive since nothing can move faster than the speed of light, but it makes sense when you take into account the expansion of space itself, not just the entire universe.

Originally Posted by Alextanium

No, because the expansion IS faster than the speed of light.

But only because the fabric of space ITSELF is expanding outward. Even though the universe is only 13.7 billion years old, the observable universe is actually around 92 billion light years across. That might sound counter intuitive since nothing can move faster than the speed of light, but it makes sense when you take into account the expansion of space itself, not just the entire universe.

Now that you say this, I remember hearing that on "The Universe", on the history channel. I still don't think that anyone can measure the age of the universe. Yet.

How do they know they can see the end of the universe? Stars just suddenly end? What if something is trapping the light more distant stars? What if there just isn't anything for a super long distance past that?

I just like to think the universe is a lot older than that. More like trillions of years.

Even though the universe is only 13.7 billion years old, the observable universe is actually around 92 billion light years across.

Is the expansion of the universe infinite times faster then light? What do you think?

-relative to the lights point of view, expansion just happens at a much higher accelerated pace then itself.

Originally Posted by Michael

I still don't think that anyone can measure the age of the universe. Yet.

Thankfully, your lack of knowledge on the subject doesn't stop science from being right

http://en.wikipedia.org/wiki/Age_of_the_universe
http://en.wikipedia.org/wiki/WMAP

We know the rate of expansion in the universe. We know the distances and speeds of objects furthest away from us. Run the equation backwards (taking into account the Hubble Constant for the expansion of space itself) and you hit a moment where the two furthest things we can see were in the same place. Doesn't get much simpler than that.

Originally Posted by Michael

How do they know they can see the end of the universe? Stars just suddenly end? What if something is trapping the light more distant stars? What if there just isn't anything for a super long distance past that?

Cosmic Microwave Background Radiation. Do a little reading.

Originally Posted by Michael

I just like to think the universe is a lot older than that. More like trillions of years.

I like to think that three beautiful women will be waiting for me in my bedroom every day when I get home from Uni. Unfortunately, that too, isn't the case. You can't even conceptualise the difference between a billion and a trillion (no one can, they are stupidly large), so why is a trillion more appealing?

Originally Posted by Dog Biscuits

Is the expansion of the universe infinite times faster then light? What do you think?

-relative to the lights point of view, expansion just happens at a much higher accelerated pace then itself.

The expansion of the universe is currently 70.5 ± 1.3 km·s-1·Mpc-1 and is accelerating. Why is it accelerating? We don't know. The running theory is that some form of energy we can't detect (yet) is responsible.

The expansion is measurable and quantifiable. It's definitely not infinite.