Topic: Like, Billions and Billions of Stars, Man. (Read 7979 times)

Joe Sixpack · « **on:** January 10, 2008, 01:01:19 PM »

Thanks to the mysterious god-like being who fixed my post count issue. This may not be a strictly technological topic, but that's what you get for having something called "The Geek Forum" without a science forum!

So, a while back, I started seeing commercials for a new show on History Channel called "The Universe".
"Nice!" I though.
Finally it came and I have been thoroughly disappointed, probably because I am not in the target audience for the show. For example, I already understand what a black hole is.
However, one episode has reminded me of a question I have been wondering about for a while.

I know and understand that light travels extremely quickly but is not infinitely fast. It takes 8 minutes for light from The Sun to reach The Earth. The nearest star to Earth, besides the Sun, is Proxima Centauri, 4 light years away. That means that light from that star takes 4 years to reach Earth, and therefore anything that happens there will not be seen by us for 4 years. Likewise, some (most!) stars are millions of light years away, and so the light we see from those stars is millions of years old. It is quite possible that a lot of the stars we see today are no longer in existence, and we will see their novas in the far future, once the light reaches us.

This leads a lot of scientists, especially ones you see on shows like "The Universe" to describe the light from distant stars as a sort of 'time machine'. You are, in fact, see what happened loooong ago. What they also say, and this is the point of confusion for me, is that the more powerful your telescope is, the farther back into the past you can see. Many say that some day a powerful enough telescope will be able to see the Big Bang, or shortly thereafter. By the above logic, that does not seem so ridiculous.

However-

The light that hits your eye or instrument is made of photons that are either emitted or reflect by the object you are looking at, are they not? As described above, those photons move at a fast but finite speed. Further, once they are past your eye, you can't see them again unless you are farther away.
If this is true, then these scientists are saying that the Big Bang happened so far away and so long ago, that the light from it has not yet reached us. If it had, it would be too late to observe it. (Yet we have observed the Cosmic Background Radiation, which is supposedly the remnant of the Big Bang. Hmmm...)

But by most current estimates, the Universe is ~13 billion years old... so this light has been traveling for that long and if it still not reached us, it would seem to be an indication that its origin is at least 13 billion light years away. If the Universe is expanding at the speed of light or slower, relative to the point of origin (if that can even be meaningful in this context), then we should see it now and at all times (CBR perhaps?), or else never if it has already passed us by. But if the Universe is expanding faster than the speed of light (again, relatively), then the light from that period will NEVER reach Earth.

Not to mention that recent data shows that the expansion of the Universe is accelerating. All these things don't seem to add up to the message that is communicated in these popular science TV programs. I think everyone interviewed on them are incredibly intelligent people, and I'm sure they have good reasoning behind the statements that they make. They just never explain what it is, so obviously I expect laymen on the internet to be able to do so.

Go ahead and burn one if you think it will help, dude.

pbsaurus · « **Reply #1 on:** January 10, 2008, 01:07:40 PM »

Because the photons from the big bang haven't reached us yet, it is actually a remnant from the future.

ivan · « **Reply #2 on:** January 10, 2008, 01:33:53 PM »

The Big Bang is not subject to current laws of physics.

The thinking is that our universe was formed by or during the Big Bang, but since the Big Bang itself was not a phenomenon of our universe, we have no way of knowing what physical laws applied.

If, as many believe, the universe expanded to a certain finite size in an instant, but then continued to expand after that, then there was an event horizon. Since we were not fortunate enough to eventually emerge near that horizon, we have to wait for information about the event horizon to reach us at the frustratingly slow pace of light speed.

Joe Sixpack · « **Reply #3 on:** January 10, 2008, 01:37:31 PM »

Umm... yeah. Hence the question in relation to the speed of light.

The Big Bang as a singularity, and it's cause, if any, obviously have nothing to with our current universe, but its immediate aftermath certainly does.

ivan · « **Reply #4 on:** January 10, 2008, 01:41:02 PM »

Matter is bound by the speed of light only within the constraints of our 3 dimensions. An intelligence that is not bound by 3 dimensions would perceive the entire history of the universe not as a unidirectional vector, but as a sphere where all the matter of the universe exists in all of its manifestations simultaneously.

Joe Sixpack · « **Reply #5 on:** January 10, 2008, 01:42:18 PM »

Slaughterhouse Five?

ivan · « **Reply #6 on:** January 10, 2008, 01:52:03 PM »

Quote from: Joe Sixpack on January 10, 2008, 01:37:31 PM

Umm... yeah. Hence the question in relation to the speed of light.

Even though the Big Bang is described as a rapid expansion, in effect the universe actually emerged all at once. This hugh giant sphere of matter just popped into existence. After that, within the universe, all kinds of things started happening, like stars forming and so on. When information about those events finally reach us, we talk about witnessing the birth of stars and so on. But we haven't yet observed anything that could be attributed to the Big Bang itself. I don't know what we expect to see -- a big flash? Bizzare levels of radiation? I don't know. But I guess we'll know it when we see it.

The idea is that what we will see will either be a phenomenon that occurred at the center of the universe, or at its edge. The fact that the edge continues to expand does not matter: we should still see something out of the ordinary that would have happened around the edges of the universe when it popped out. So the thinking is that we are somewhere between the center and the edge of the sphere of original universe, and both are so distant that light from those events has not yet reached us.

ivan · « **Reply #7 on:** January 10, 2008, 01:55:07 PM »

Quote from: Joe Sixpack on January 10, 2008, 01:42:18 PM

Slaughterhouse Five?

Exactly. I've been trying to unstick myself for decades.

Joe Sixpack · « **Reply #8 on:** January 10, 2008, 02:03:55 PM »

Quote from: ivan on January 10, 2008, 01:52:03 PM

Even though the Big Bang is described as a rapid expansion, in effect the universe actually emerged all at once. This hugh giant sphere of matter just popped into existence. After that, within the universe, all kinds of things started happening, like stars forming and so on. When information about those events finally reach us, we talk about witnessing the birth of stars and so on. But we haven't yet observed anything that could be attributed to the Big Bang itself. I don't know what we expect to see -- a big flash? Bizzare levels of radiation? I don't know. But I guess we'll know it when we see it.

The idea is that what we will see will either be a phenomenon that occurred at the center of the universe, or at its edge. The fact that the edge continues to expand does not matter: we should still see something out of the ordinary that would have happened around the edges of the universe when it popped out. So the thinking is that we are somewhere between the center and the edge of the sphere of original universe, and both are so distant that light from those events has not yet reached us.

Right. The question is, why do we act like it will? It seems like it either would have already reached us, in which case it is passed, and we wouldn't see it again, OR it's so far away that we either won't survive long enough to see it or the universal expansion is of such a speed that it is relatively greater than the speed of light, in which case it would be impossible to see it.

dcrog · « **Reply #9 on:** January 10, 2008, 02:07:16 PM »

Be careful Joe. This could happen to you with this line of thinking.

Joe Sixpack · « **Reply #10 on:** January 10, 2008, 02:08:07 PM »

Lucky for me, I've already had that.

pbsaurus · « **Reply #11 on:** January 10, 2008, 02:11:41 PM »

Perhaps the answer lies in timecube.

ivan · « **Reply #12 on:** January 10, 2008, 02:45:38 PM »

Quote from: Joe Sixpack on January 10, 2008, 02:03:55 PM

Right. The question is, why do we act like it will?

Because we're vain.

The universe is 14 billion years old. Our Sun and Earth are 5 billion years old. Mammals are 70 million years old. Primates are 63 million years old. Humans are 200,000 years old. The telescope is 400 years old. Radio is 100 years old. The term "Big Bang theory" is just over 50 years old. And yet we think that light from the event horizon will reach us... now. Ok... Wait for it... NOW!

Dang.

Well, maybe the aliens who are visiting us... now... have an idea when we might see the Big Bang.

Joe Sixpack · « **Reply #13 on:** January 10, 2008, 02:54:33 PM »

There are no aliens or ghosts.

But there are demons.

Agent_Tachyon · « **Reply #14 on:** January 10, 2008, 11:31:52 PM »

Quote from: Joe Sixpack on January 10, 2008, 01:01:19 PM

Go ahead and burn one if you think it will help, dude.

Tried to no avail dude. However, here is a puzzler of my own. It's from an old Calvin and Hobbes comic I read as a kid, one of the ones where Dad tries to fuck with Calvin's head (probably as payback for all the awesome mayhem Calvin always caused). Dad explains how a dot on the outer track of a phonograph record has a longer distance to travel in a rotation, relative to a dot close to the center. But they somehow made it the trip in the same time, meaning that they are moving at different speeds somehow.

I think the last frame was Calvin grimly staring at the ceiling at night, and it's a bit like me now, but I'm staring at the computer.

Joe Sixpack · « **Reply #15 on:** January 11, 2008, 10:12:52 AM »

I can think of a way to do it offhand, although I'm not sure if it's how a record player actually works.

Assuming this is a serious question (quite an assumption around here).

dcrog · « **Reply #16 on:** January 11, 2008, 12:05:55 PM »

Rate x time = distance.

You have to equate the distance each is traveling in the same revoultion/time.

BizB · « **Reply #17 on:** January 11, 2008, 01:13:44 PM »

We will never see the big bang. It just won't happen. Why? Because our luck is such that, just at the moment that we would witness the event, there will be a guy returning from the concession stand with a big ass box of popcorn and he'll walk directly in the way at the critical moment.

It's just our luck.

Joe Sixpack · « **Reply #18 on:** January 11, 2008, 01:21:00 PM »

But, man, just think. If we WERE that fat guy...

dcrog · « **Reply #19 on:** January 11, 2008, 01:22:18 PM »

I was talking about the dots on the record. I can't think deep enough to get into the whole big bang theory.

Oh, and Agent since the outside spins faster than the inside, why doesn't the music speed up the closer you get to the center of the record?

Joe Sixpack · « **Reply #20 on:** January 11, 2008, 01:42:08 PM »

Seems to me, the arm moves in as the record plays, so there is a way for it to know where in the groove the needle is located, and therefore turn the record more slowly as it moves toward the center. Like I said, I have no idea if that's how it actually works.

ivan · « **Reply #21 on:** January 11, 2008, 01:42:46 PM »

Because the music was recorded at the same speed as that at which it is played back. If you record a rhytmic click and look at the tracks under a microscope, the bumps on the outer rim will be spaced farther apart than the ones on the inner tracks.

A dot on the outer rim of an LP and a dot near the center are traveling at different speeds relative to a point outside the disk. The longer the radius of their arc around the center, the greater their speed -- in direct proportion.

However, the dot on the outside and the dot near the center both have the same average velocity -- zero.

pbsaurus · « **Reply #22 on:** January 11, 2008, 01:43:29 PM »

Quote from: BizB on January 11, 2008, 01:13:44 PM

We will never see the big bang. It just won't happen. Why? Because our luck is such that, just at the moment that we would witness the event, there will be a guy returning from the concession stand with a big ass box of popcorn and he'll walk directly in the way at the critical moment.

It's just our luck.

I would say that at the moment, people would actually be glued to the boobtube watching some Brittney coverage or something and miss the whole thing.

dcrog · « **Reply #23 on:** January 11, 2008, 01:45:18 PM »

Quote from: ivan on January 11, 2008, 01:42:46 PM

Because the music was recorded at the same speed as that at which it is played back. If you record a rhytmic click and look at the tracks under a microscope, the bumps on the outer rim will be spaced farther apart than the ones on the inner tracks.

I knew that. I was messing with Agents brain.

If you were standing on the center of the spindle looking at the dots they would appear to never move.

ivan · « **Reply #24 on:** January 11, 2008, 01:46:50 PM »

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