APOD: A Flight Through the Universe (2012 Aug 13)

[BMAONE23]

Great piece of work!!!
I think that if we ever were able to travel at that speed, the apparent motions of the galaxies (galactic rotation) would become apparent as we would encounter the light faster in the direction we were traveling, they would appear to speed up in their rotations. Then, as we passed the galaxies, they would appear to rotate in reverse.

[Anthony Barreiro]

... . The movie starts by flying right through a large nearby cluster of galaxies ... .

Would that be the Virgo cluster?

This is a lovely video. It puts all my little problems and disappointments into perspective.

[marlan]

I don't understand the purpose of this amazing video, showing the Univers which doesn't exist as such NOW. We have no idea what is the current position and look of a galaxy distant a hundred millions of light-years. The images we get are the ones of the past. So ?

[Chris Peterson]

I don't understand the purpose of this amazing video, showing the Univers which doesn't exist as such NOW. We have no idea what is the current position and look of a galaxy distant a hundred millions of light-years. The images we get are the ones of the past. So ?

The purpose is just to provide a sense of the scale of the Universe.

If you could fly through the Universe in reality, everything would look about the same. That's because all galaxies are about the same age. No place in the Universe looks substantially different than any other place. It only appears that way to us, observing from a single location, and therefore seeing more distant stuff as it appeared when younger.

[Moonlady]

and this amazing flight was very very quiet to my earthlings ears

[neufer]

I think that if we ever were able to travel at that speed, the apparent motions of the galaxies (galactic rotation) would become apparent as we would encounter the light faster in the direction we were traveling, they would appear to speed up in their rotations. Then, as we passed the galaxies, they would appear to rotate in reverse.

You are half right.

Galaxies ahead of us will appear to run in a time frame speeded up a factor of ~2γ.
(Where the ultrarelativistic "warp factor" γ ~ 376 trillion.)

However, in order for one to observe time to appear to move backwards
one must catchup with and pass photons that have already passed us by.

This is not possible in a vacuum

Rather, galaxies behind us will appear to run in a time frame slowed up a factor of ~2/γ.

[Lordcat Darkstar]

seeing this video causes me to wonder. If everything in the visible universe originated from the big bang, than that means that there should be a center to the universe right? Would it be possible to maybe find hints or clues from this data that could point us in the direction of the center of the universe? Im sure we would need a lot more data and we would probably have to figure out where everything is now, but I think it would be interesting to be able to point at a part of the sky and say thats where it all began.

[Ann]

seeing this video causes me to wonder. If everything in the visible universe originated from the big bang, than that means that there should be a center to the universe right? Would it be possible to maybe find hints or clues from this data that could point us in the direction of the center of the universe? Im sure we would need a lot more data and we would probably have to figure out where everything is now, but I think it would be interesting to be able to point at a part of the sky and say thats where it all began.

As Chris Peterson once pointed out, the only center of the universe is the precise moment of the Big Bang itself. This moment is the center of the universe because everything originated from it, but we can't see it, because it is located about 13.7 billion years ago.

So aren't there parts of the universe which are closer to the Big Bang than other parts? Sure, the distant galaxies that are spotted by our most powerful telescopes are closer to the Big Bang than we are, but only because we see them as they were in the past. "Now" these galaxies are as far away from the precise moment of the Big Bang as we are.

Isn't there a physical, three-dimensional part in our present-day universe which is closer to the Big Bang than other parts? Can't we point at a certain constellation or star in the sky and say that the Big Bang happened in this particular direction of the universe around us? No. Because the Big Bang wasn't a sort of "flame-thrower" that ejected its stuff into a pre-existing space. The entire universe, space itself, was created in the Big Bang, so no part of space is "closer" to the Big Bang than any other part of it. As a matter of fact the entire universe is the Big Bang, when it is 13.7 billion years old and has cooled and expanded. That's a hard concept to wrap one's mind around, but it is nevertheless true.

See viewtopic.php?f=30&t=25300.

Ann

[nz1m]

This is a tremendous effort. Thank you. However, have you ever considered this: We all know the farther away we gaze the farther back in time we're looking. So, this map is really a very, very old map. Could we extrapolate "where the galaxies would be now"? Since we could never, ever, travel there, it may be moot. But "now" maps are indeed more accurate for the serious traveler!

[neufer]

This is a tremendous effort. Thank you. However, have you ever considered this: We all know the farther away we gaze the farther back in time we're looking. So, this map is really a very, very old map. Could we extrapolate "where the galaxies would be now"? Since we could never, ever, travel there, it may be moot. But "now" maps are indeed more accurate for the serious traveler!

The primary motion involved here is Hubble expansion. Either Hubble expansion has already been included or it amounts to basically a simple scaling factor such that the separation between galaxies is slightly more than shown (as a function of the galaxy sizes).

On the other hand, the individual separations between neighboring galaxies is mostly dominated by local motions such as that which will cause a (near?) collision between the Milky Way and the Andromeda galaxy in ~4 billion years. Since the furthest galaxies depicted are about 1.25 billion years old there will, indeed, be some distortions in the more distant structures. However, since we have no way of knowing about any of the angular local motions taking place with even nearby galaxies (much less distant ones) only the radial distances could be corrected for in the manner you wish.

[rstevenson]

In this video, is the per-galaxy scale the same as the distance-between-galaxies scale?
It doesn't look right to me.

Previous representations are more like cartoons as compared with this careful representation.

Thanks for that Art-full opinion. I also asked on the SDSS-III blog and got this reply...

Yes, the galaxy sizes have been increased by a significant factor for visibility. They otherwise would be dots except for times when you were flying rather near a galaxy. (If I recall correctly, that factor is around 50x).

Rob

[Denise]

Thanks APOD and Sloan Digital Survey for the astonishing video! I also greatly enjoyed seeing the other videos folks posted, fascinating discussion too.

[Cheap Frill]

This video is a fake! You can see the guy's boots when he pans the camera past the Ophiuchus Supercluster. I'll bet they're not even real galaxies, just nebulae dressed up to look like galaxies!

[Aodhan Warchilde]

When I was a child I tried to picture what it would be like to fly through the stars (what I could see of them.) Wonderful to have grown up and find that the reality is more magical than the imagination. I don't know how "real" it is, or if the photons "bunch up in front of you" -- but the video is fascinating!

[neufer]

I think that if we ever were able to travel at that speed, the apparent motions of the galaxies (galactic rotation) would become apparent as we would encounter the light faster in the direction we were traveling, they would appear to speed up in their rotations. Then, as we passed the galaxies, they would appear to rotate in reverse.

You are half right.

Galaxies ahead of us will appear to run in a time frame speeded up a factor of ~2γ.
(Where the ultrarelativistic "warp factor" γ ~ 376 trillion.)

However, in order for one to observe time to appear to move backwards
one must catchup with and pass photons that have already passed us by.

This is not possible in a vacuum

Rather, galaxies behind us will appear to run in a time frame slowed down a factor of ~2/γ.

Correction: galaxies behind us will appear to run in a time frame slowed down a factor of ~1/2γ

Yellow light from destination galaxies are received as ~ 1,750 TeV gamma rays
Yellow light from trailing galaxies are received as ~ 1 Hz radio waves.

Now that's real Doppler effect

[Marcus44]

Is the diameter of those galaxies right? I mean the proportions between size of them and distances... Galaxies appear so ...big here. :/

[bystander]

Is the diameter of those galaxies right? I mean the proportions between size of them and distances... Galaxies appear so ...big here. :/

I also asked on the SDSS-III blog and got this reply...

Yes, the galaxy sizes have been increased by a significant factor for visibility. They otherwise would be dots except for times when you were flying rather near a galaxy. (If I recall correctly, that factor is around 50x).

[GerryP]

I normally like and appreciate almost every photo/video posted in APOD (Thanks to everyone behind the scenes !), I eagerly check it out almost everyday (since last 1 year or so). As for today's (Aug 13th, 2012) video, to be honest, I didn't find this video much exciting at all. There's almost nothing in it except galaxies, galaxies and more galaxies (either individual or in clusters). Nothing else. Not sure if I'm missing some point.

I think that the point is that it is just galaxies. It gives just a small perception of how staggeringly huge the universe is. Just imagine that some of those little dots are larger than the Milky Way itself. The skill and technology to put a video like that together are also astounding. Isn't it great to be able to see something like that?

[Marcus44]

I normally like and appreciate almost every photo/video posted in APOD (Thanks to everyone behind the scenes !), I eagerly check it out almost everyday (since last 1 year or so). As for today's (Aug 13th, 2012) video, to be honest, I didn't find this video much exciting at all. There's almost nothing in it except galaxies, galaxies and more galaxies (either individual or in clusters). Nothing else. Not sure if I'm missing some point.

I think that the point is that it is just galaxies. It gives just a small perception of how staggeringly huge the universe is. Just imagine that some of those little dots are larger than the Milky Way itself. The skill and technology to put a video like that together are also astounding. Isn't it great to be able to see something like that?

Exactly. In the first second i thought: geee... we are so trivial, unessential in this huge space. Only a deep, black silence and small blue spot of live... But second was: wow, it so big, so spraed, that there must be full of live there.

[arbee63]

An amazing video that truly emphasizes both the vast scale of intergallactic space and just how many galaxies are out there...each with their billions of stars...
I know such a flight is not physually possible becasue of relativity and the fact that images of distant galaxies represent a different point in time, but how "fast" is the observer moving in the video? It must be many millions of light years per second?

[neufer]

An amazing video that truly emphasizes both the vast scale of intergalactic space and just how many galaxies are out there...each with their billions of stars...
I know such a flight is not physically possible because of relativity and the fact that images of distant galaxies represent a different point in time, but how "fast" is the observer moving in the video? It must be many millions of light years per second?

Yes:

• viewtopic.php?p=181492#p181492
• viewtopic.php?p=181670#p181670