It's a small world, after all.

[Sebastiani]

I love this video.

[Mario F.]

The universe is out of this world.

I regret having been born in this time and age in which we are still, and will probably be for a very long time, a backward sedentary civilization. Out there is where I would like us to be.

[stevesmithx]

Very Nice video. But I would like to see the video go and explore the other way around.
From bigger to smaller(from light years to atomic).
Whilst we know what constitutes an atom, i don't think we know what constitutes the constituents of an atom. At the end of that video they say that we are not at the center of the universe. Whilst it is highly probable that it could be true, i don't think something like that could be said for sure for an object whose boundaries are unknown.

[Sebastiani]

>> But I would like to see the video go and explore the other way around.
From bigger to smaller(from light years to atomic).

That would be pretty cool (but extremely mind-boggling).

>> Whilst it is highly probable that it could be true, i don't think something like that could be said for sure for an object whose boundaries are unknown.

I would think that the universe is boundless. And even if it is a continuum, it still would have no center. Just as if you were standing somewhere on earth you could not say that you you were at the central point on the surface of the earth.

[Spidey]

Ah, nice. But this one will always be my favorite - Powers Of 10
It goes from small to big and then big to small.

[whiteflags]

Very Nice video. But I would like to see the video go and explore the other way around.

Wish granted.

[valaris]

Wish granted.

Was just about to post this I can't recall the number of times I watched this thing through middle and high school.

[stevesmithx]

Wish granted.

Woot.

[Elysia]

I have never before heard of Ångström. I have heard of Nano, however, so I fail to see why they wouldn't use nanometer and picometers instead of Ångström for small measurements...

At the end of that video they say that we are not at the center of the universe. Whilst it is highly probable that it could be true, i don't think something like that could be said for sure for an object whose boundaries are unknown.

Except the the universe is expanding, so if it were expanding different amounts on different sides, it would be impossible for us to be in the center.
It is also worth pondering on Sebastiani's mention too.

[MK27]

I have never before heard of Ångström. I have heard of Nano, however, so I fail to see why they wouldn't use nanometer and picometers instead of Ångström for small measurements...

Clearly you don't remember how the communists have tried to fool the American public with the metric system several times already -- I think that is part II of the video

I'm pretty sure the universe does have a theoretical center, BTW, since space is a property (or effect) of mass and all mass in the universe began with a single event. The message is YOU are not that center. Hopefully. It should be easy to tell, because everything will be moving away faster than you can count.

[Elysia]

Clearly you don't remember how the communists have tried to fool the American public with the metric system several times already.

No, never heard of that...

[Mario F.]

One of the most thought provocative concepts of the expansion of the universe was the idea that relative speeds may lead to objects distancing themselves at speeds faster than the speed of light, making them invisible to each other.

The idea was recently dismissed when it was found the universe expansion metric is always changing (from observations that seemed to prove the isotropic and homogeneous nature of universe expansion). But that thought nagged me for a very long time.

[MK27]

One of the most thought provocative concepts of the expansion of the universe was the idea that relative speeds may lead to objects distancing themselves at speeds faster than the speed of light, making them invisible to each other.

You would not be able to see them then

Isn't speed always relative? According to the general theory of relativity, the speed of light is always a constant relative to you, ie, no matter how fast you go, light will always seem to be going the same speed around you (just the wavelengths changes, so you get eg. redshift). I think that is the sense in which nothing can exceed the speed of light.

So that means relative to say, Earth and Alpha Centauri, you could get an object travelling "faster" than the speed of light! I'm fcc'ing this off to NASA now...

[Mario F.]

No. It would be slightly different. The objects could be moving at a speed slower than the speed of light. So any observer in the middle of them, for instance, could observe them. But their movement relative to each other could amount to a speed larger than the speed of light. Same as the relative speed of of a car moving in the opposite distance as mine, is the sum of our speeds.

I always found this disturbing because the larger the distance, the more close to the speed of light these objects travel as demonstrated by their redshift. So it is easy to assume we would stop seeing any objects beyond a certain boundary. But if that was the case, the observable universe was not the whole universe. And that being the case, we could never even pretend to know the age of the universe, which could infinitely older than our current estimates, neither we could ever assume to understand the actual redshift. And to make things even more complicated, the existence of other objects beyond our current observation horizon wouldn't fit well into many current theories...

This is more or less the problem Hubble himself faced when he later analyzed the results of his own findings. And what is amazing about this man was the he was indeed right. He helped set the pace of modern astronomy, and later questioned the validity of his own theories which proved him right again many years later. An extraordinary man.

[MK27]

No. It would be slightly different. The objects could be moving at a speed slower than the speed of light. So any observer in the middle of them, for instance, could observe them. But their movement relative to each other could amount to a speed larger than the speed of light.

Okay, the NASA people have not gotten back to me yet *but* once the object in space, going 1 million mph, relative to it, the Earth is moving 1 million mph -- it is not moving at all, which is why light is still the same speed, not c - 1000000. So if the object kept accelerating indefinately (which acceleration is thrust, ie, displacing matter -- it works because you are, in effect, not moving, and you displace some matter, causing you to move. From a third perspective, you were moving to start with, so it is relative acceleration) eventually, from the perspective of Earth, it will appear to be moving close to the speed of light. From the object's perspective, the Earth is moving. I suspect beyond that point, you could not make any further observations, so while the object relative to Earth might be moving faster than light, you would not see it. And the object, relative to itself, would still not be moving, but will no longer see Earth.

See? there are some loopholes in the contract. According to this, for example, "If a laser is swept across a distant object, the spot of light can easily be made to move at a speed greater than c."* Which seems paradoxical -- making a light beam move faster than light, but of course, the light in the beam did not have to change speed.

*It's in chapter 3 and it was done with the moon; apparently a parallel "of this has been observed when an electromagnetic pulse from a lightning flash hits an upper layer of the atmosphere."