Question 1

If the law says that matter cannot be created, so can the big bang create matter?

Accepted Answer

Within the Start of Time and the "Planck Time", which is the smallest possible unit of time (about 10^-84 s), no laws apply. All matter is crated. Then, in the inflation period, *standard* laws still don't apply, however there were some different laws in this period.

Question 2

where can I find more information of SpaceTime?

Accepted Answer

Try the Astronomy section on Khan Academy.

Question 3

so if I am right everything in the universe is expanding away from each other. So does that mean one day we wont see stars because they are too far away?

Accepted Answer

Yes, I believe so.  Stars and galaxies will continue to expand further from us, making it harder to see. We are at what astronomers consider the prime time for astronomy. With breakthrough technology helping us discover the universe, and being able to see all the twinkling stars and discover new things, this period is a great one for astronomers.

Question 4

How is it possible that there was no time before the Big Bang?

Accepted Answer

Time cant exist without space, that's why physicists refer to it as one concept: "Spacetime". Before the big bang, there was no space, so there was no time. As humans we experience time because we are products of the big bang. Without the big bang there would be no objects and therefore, nothing would change (which is all that time is, the phenomenon of objects in space changing from one state to another).

Question 5

At around 9:35, the Hank subtitle says that only about 1% of the static heard is Cosmic Background Radiation. Is this because of interference from other earthly sources, and if so, would it be better heard in deep space?

Accepted Answer

Yes, which is why we've sent multiple space telescopes up to measure it. COBE, WMAP and most recently Planck.

Question 6

I have a slight countertheory for the "Either not infinite, not eternal, etc." part. If light has the a certain speed, and we're many many billions of light-years away, what's to say we won't be able to see those stars someday? What if it is all three, and we have the concept wrong?
Another question/countertheory to my countertheory: If the universe is infinite, and there's infinite matter, and it's only 1 billionth of the total amount that existed, would that mean the universe is infinite, or that infinity really does reach a certain stopping point?

Accepted Answer

"If light has the a certain speed, and we're many many billions of light-years away, what's to say we won't be able to see those stars someday?"

>If its billions of light years away it will take billions of years for the light to reach a human to see it. Thinking logically humans and the earth won't be around long enough to see it. Also it can't be all three look into the definitions.

"If the universe is infinite, and there's infinite matter, and it's only 1 billionth of the total amount that existed, would that mean the universe is infinite, or that infinity really does reach a certain stopping point?"

>No...it could still very well be infinite,

I think you could benefit from looking more into the concept of what infinity actually mean...for example some infinities can be larger then other infinities as explained with the Hilbert's paradox of the grand hotel.

Question 7

Were the time increments "a fraction of a second" and  "10 seconds" after the big bang for the Universe to expand would the time increments mentioned be affected by the expansion or are they being measured in our seconds?

Accepted Answer

Hmm, good question. My guess would be that scientists predicted that that's how long it would take in our time and perspective, but I'm not sure.

Question 8

Is the speed of the universe expanding akin to the speed of light or is it faster? Also if we hypothetically reached a greater speed of the universe expanding what would happen if we cross the threshold of the so called 'edge of the universe' what would happen if we manage to surpass the speed of the universe expanding and we go beyond the universe. I hypothesis that it beyond that there wouldn't be spacetime and it would be the same as what it was like before the big bang. So what would happen to a person if they go beyond the universe?

Accepted Answer

There is no speed of the universe. That would require some spatial reference external to the universe with which to measure against, which by definition does not exist.

There is a rate of expansion which, if it has any positive value, if two points in the universe are far enough apart, they will experience a relative velocity to each other of greater than the speed of light, regardless if each of them are moving through space or not.

Question 9

How did that teeny tiny atom inflate into a thing trillions of times bigger than that atom? It doesn't make sense that a tiny atom could explode into a trillions of blue whales sized stuff ,I mean bigger than trillions of blue whales size stuff bigger than itself.

Accepted Answer

It wasn't an atom. Atoms didn't exist then. It was extremely dense energy.

Question 10

So  before the big bang there was no space and there was to time (there was no space-time).  How can stuff be created when there is no space and there is no time? And how can there be "no then then"?

Accepted Answer

That's one of the biggest mysteries in theoretical physics, but there are many plausible theories on it. One is the cyclic universe, which posits that the universe is on an endless cycle in which it expands, collapses back into a singularity (an infinitesimal point), and bounces back again. Another theory is the multiverse, which posits that the universe is just one of many other "verses," which form and collapse as time passes.

Course: Big History Project > Unit 1

WATCH: The Big Bang

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