I don't understand

[joe-90]

If you sit and talk to your dog about tomorrow, it won't have a clue what you are saying.

If some spaceman came and told us the answer to infinity and eternity, we couldn't grasp it any more than the dog can. So what's the point in postulating?

 

[UriBentMySpoon]

Postulating and speculating leads to ideas, leads to possible testable hypotheses, leads to an expansion of human knowledge.

Its called science Joe90. We need to have ideas so we can pursue them, see where they lead, whether it be scientific truth or naught. Check out Phlogiston theory, you need to have an idea to explain something and then you can find the experiment.

 

[UriBentMySpoon]

Why would it need to expand faster than the speed of light? There is not a "wall" for the light to bounce back off.

otherwise the light from the infinite stars would have reached us, therefore the sky would be white.

Light changes as it travels, it moves from our visible spectrum. That is why the telescopes that look the furthest into space, therefore further back into time, are radio telescopes and not the traditional mirror based telescopes.

Check out redshift on Wikipedia.

 

[EddieM]

Why would it need to expand faster than the speed of light? There is not a "wall" for the light to bounce back off.

otherwise the light from the infinite stars would have reached us, therefore the sky would be white.

Light changes as it travels, it moves from our visible spectrum. That is why the telescopes that look the furthest into space, therefore further back into time, are radio telescopes and not the traditional mirror based telescopes.

Check out redshift on Wikipedia.

its ok, i understand doppler (red shift) effects, but the rest, no.

 

[UriBentMySpoon]

Okay. Think about moving two dimensionally only, forward/backward and left/right. If you were to walk across the surface of this Earth, you will never reach the end as there isn't an end. Imagine the Universe like that, you will keep moving on forever. We can measure the distance between our galaxy and others. They are on the whole moving apart. Reverse time and you have everything converging on one point, this is the basis of the Big Bang Theory. Even though the Universe does not have an edge, the galaxies are nevertheless moving apart, therefore the Universe must be expanding to accommodate.

Similar to why the night sky isn't lit by the stars, the question has been asked, why can we not see the light of the Big Bang? You can, in the cosmic background radiation of the Universe. The light is not visible in our spectrum but it is still there.

 

[joe-90]

If light slows down to pass through glass - how does it speed up again?

 

[UriBentMySpoon]

If light slows down to pass through glass - how does it speed up again?

Good question Joe, I do not honestly have the answer, I did hear though they managed to slow down light to something stupidly slow like 40 mph through some gas mixture I believe.

 

[joinerjohn]

If light slows down to pass through glass - how does it speed up again?

That's an excellent question Joe. And I bet no one here can explain it.

 

[UriBentMySpoon]

If light slows down to pass through glass - how does it speed up again?

That's an excellent question Joe. And I bet no one here can explain it.

There isn't a question in this world Joe cannot answer, I be t he already knows.

Bet Joe can calculate pi to the nth degree.

 

[joe-90]

I can answer every question on University Challenge.

Whether I get the right answer is another matter.

 

[Hysteresis]

OK - Whilst we have all of the Physicists here.
If the 'BIG BANG' was a fact, which Prof Hawing is pretty damn sure it is, then all matter expanded from that singularity. If that is the case then as everything is travelling away from the singularity, there must be a big void at the source of the Big Bang, as everything is travelling away from it. It should be 'easy' enough to get to the source of the Big Bang, as everything is travelling away from it, surely a good pointer to is source, then if its source should be Identifiable, then there should be an enormous void there, so big that it should have been identified by now. Or maybe there isn't a big void and therefore NO BIG BANG !!!!!!
Have all of these Astro Physicist missed something very obvious here ????
It has always puzzled me.
Joe 90 will know.

 

[UriBentMySpoon]

Everywhere was the source of the Big Bang. The Big Bang was everywhere and is everywhere. There is no centre to the Universe. Just your position/perspective.

 

[Hysteresis]

Everywhere was the source of the Big Bang. The Big Bang was everywhere and is everywhere. There is no centre to the Universe. Just your position/perspective.

My take on the Big Bang is that everything is travelling away from everything else, the red Shift and all of that. So, reverse that process and you end up with the hypothesis of the Singularity 14 billion years ago. Simple !!!!!!!
If the Big Bang was everywhere as you suggest, the particles that make up the Universe would have nowhere to expand into and therefore all particles would not be travelling away from all other particles.
My perception is somewhat limited by my very limited imagination, but all present thoughts of the clever guys is that it all started with a singularity. Maybe that singularity gave birth to multiple Universes, the so called Multiverse hypothesis, as such our observable universe is no more than a bubble in that multiverse, a bubble which is in itself expanding and, as we cannot observe the void to which I refer, then maybe that void is outside our observable 'bubble'.
But where this breaks down is that the Big Bang theory was derived from our observable Universe and what has been observed suggests the Big Bang singularity, as such the source of the Big Bang must be in our observable bubble/universe
Any thoughts on those thoughts UriBentMySpoon?

 

[joe-90]

What i don't understand is why all this stuff didn't happen an infinite time ago. What happened to create something (a universe) where nothing existed before? And 14 billion years isn't long. We borrowed 14 billion quid just last month. In a cosmic scale it's just like yesterday. So where did the singularity come from? If the universe expands until gravity pulls it back again, are we some kind of universal yo-yo? If we are, how did it all start?

 

[EB1caneyeB]

Apparently a lot of the stars we see now are already invisible (they implode i think). We are only seeing the light that used to shine from them. It's just taken so long for that light to reach us.

It could do your head in, trying to understand it all.

When i was a kid and couldn't sleep at night i used to sit in my bedroom window (on the cill) and star gaze. One night i decided to count them all. Did you know that one night in the sky over south london, in the summer of 1977, there were 710 stars visible to the naked eye (give or take 100). That same night i observed the man at number 15 was having an affair with the divorcee (used to leave her bedroom curtains unpulled...ooo) who lived opposite my house. Damn near put me off my star counting....lol