The Hubble Ultra Deep Field in 3D

Vic

Elite Member
Jun 12, 2001
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Originally posted by: Analog
Originally posted by: Vic
Originally posted by: Analog
Interesting. However, they claim some galaxies are moving away from us at greater than the speed of light. I thought that to be impossible.

http://www.youtube.com/watch?v=oAVjF_7ensg

The combined speeds are greater than the speed of light. We're moving too. :)

According to Einstein, it doesn't work that way.. :D

Einstein never fully accepted the theory of the Big Bang either. No single particle of energy or matter is moving faster than the speed of light here, it's just the expansion of the universe.
 

RESmonkey

Diamond Member
May 6, 2007
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How are the galaxies traveling away from us faster than the speed of light? Isn't that not allowed by special relativity? I haven't studied any of that yet; just read some stuff.
 

nick1985

Lifer
Dec 29, 2002
27,153
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Originally posted by: RESmonkey
How are the galaxies traveling away from us faster than the speed of light? Isn't that not allowed by special relativity? I haven't studied any of that yet; just read some stuff.

We are moving away from them, and they are moving away from us. Add that speed together and its > light

Think of two people walking away from each other. Sure, both people are just walking, but add those 2 speeds together and its a jog.
 

RESmonkey

Diamond Member
May 6, 2007
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Originally posted by: silverpig
Originally posted by: Vic
Originally posted by: Analog
Interesting. However, they claim some galaxies are moving away from us at greater than the speed of light. I thought that to be impossible.

http://www.youtube.com/watch?v=oAVjF_7ensg

The combined speeds are greater than the speed of light. We're moving too. :)

That's not why... It's because of that plus the expansion of space in between us :)

Neato
 

badkarma1399

Senior member
Feb 21, 2007
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Actually, It is possible for two objects to move faster than the speed of light, relatively speaking. While objects cant move faster than the speed of light, space can expand faster than the speed of light. Two objects can be perfectly still, but due to the space in between them expanding faster than light, the light from one will never reach the other. This is how the universe is around 93 billion light years across but only 13 billion years (around there?) old. Its also how FTL travel could hypothetically be achieved by a warp drive :D
 

RESmonkey

Diamond Member
May 6, 2007
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Originally posted by: badkarma1399
Actually, It is possible for two objects to move faster than the speed of light, relatively speaking. While objects cant move faster than the speed of light, space can expand faster than the speed of light. Two objects can be perfectly still, but due to the space in between them expanding faster than light, the light from one will never reach the other. This is how the universe is around 93 billion light years across but only 13 (around there?) old. Its also how FTL travel could hypothetically be achieved by a warp drive :D

Super Neato!
 

Martin

Lifer
Jan 15, 2000
29,178
1
81
Mesmerizing.

Also it's quite astounding to think that there are substantial numbers of people in this world that:
1. Look at this and see nothing
2. Think it is a giant conspiracy put together for the so scientists can make money.
 

destrekor

Lifer
Nov 18, 2005
28,799
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Originally posted by: silverpig
Originally posted by: Analog
Interesting. However, they claim some galaxies are moving away from us at greater than the speed of light. I thought that to be impossible.

http://www.youtube.com/watch?v=oAVjF_7ensg

It's impossible to have a relative velocity greater than light in space yes, but space is expanding.

that poses an interesting, mind-boggling question:

while nothing can move faster than the speed of light in space, can the expansion of space cause matter to move faster than light?

While it makes sense that two objects moving away from each other, when viewed from one object, would represent movement at faster than light (point a looking at point b, both moving away, by observing from point a makes point b appear to move faster than light away from point a. yes i just repeated, in different terms. no i don't care. :p)... could it be possible that an object (point A) would remain stationary in terms of relative space, while another object actually moved 'away' at a speed faster than light? Not two objects moving away from each other, but one object moving away from the other, 'on its own', so to speak.
The expansion of space itself, on many levels, at this current point in time, breaks just about every theory we have established, and while 'proving' a few, doesn't help any situation. It completely shatters our elementary understanding of what it is we occupy. So to say we have an absolute grip of astrophysical laws is really perplexing, when we haven't physically observed or proven many of the ones we've established. Most are very well grounded and while nearly impossible to physically prove, observed evidence helps establish those 'rules'. But others, are beyond being pegged 'scientific theories' and are strictly 'theories', because while astrophysicists and mathematicians think they are grand rules, we really don't have the depth and physically observed evidence that would paint the picture clearly.
 

Vic

Elite Member
Jun 12, 2001
50,422
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Originally posted by: silverpig
Originally posted by: Vic
Originally posted by: Analog
Interesting. However, they claim some galaxies are moving away from us at greater than the speed of light. I thought that to be impossible.

http://www.youtube.com/watch?v=oAVjF_7ensg

The combined speeds are greater than the speed of light. We're moving too. :)

That's not why... It's because of that plus the expansion of space in between us :)

I addressed that in my 2nd post in this thread :)

If the universe is expanding through time at or near the speed of light, then space must necessarily be expanding at an even faster rate.

 

destrekor

Lifer
Nov 18, 2005
28,799
359
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Originally posted by: silverpig
Originally posted by: Vic
Originally posted by: Analog
Interesting. However, they claim some galaxies are moving away from us at greater than the speed of light. I thought that to be impossible.

http://www.youtube.com/watch?v=oAVjF_7ensg

The combined speeds are greater than the speed of light. We're moving too. :)

That's not why... It's because of that plus the expansion of space in between us :)

well technically, isn't it the expansion of space that is causing clusters and galaxies to move away from each other in perspective?

from what I have gathered, astronomers haven't described galaxies as orbiting anything else, other than maybe the internal components of galaxies orbiting a central mass, be it a super massive star (not likely in modern times - old galaxies maybe, but the modern universe doesn't have the amount of matter to build massive stars, all the original massive stars burnt out not long after they were created, in universal history, not in human reference time), massive black holes, or massive clusters of dark matter.
Point being, since it doesn't appear that galaxies orbit anything, they're formation would be in a stable, stationary position, and they're drift would be directly related to the expansion of space, yes? That's how I understand it, but I thoroughly understand that I might be completely wrong. :p
It just seems that matter randomly drifting, if not in orbit, would mean something would have to had provided a force of acceleration, and the expansion of space seems to be the only answer in that instance.
 

RESmonkey

Diamond Member
May 6, 2007
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Originally posted by: destrekor
Originally posted by: silverpig
Originally posted by: Analog
Interesting. However, they claim some galaxies are moving away from us at greater than the speed of light. I thought that to be impossible.

http://www.youtube.com/watch?v=oAVjF_7ensg

It's impossible to have a relative velocity greater than light in space yes, but space is expanding.

that poses an interesting, mind-boggling question:

while nothing can move faster than the speed of light in space, can the expansion of space cause matter to move faster than light?

While it makes sense that two objects moving away from each other, when viewed from one object, would represent movement at faster than light (point a looking at point b, both moving away, by observing from point a makes point b appear to move faster than light away from point a. yes i just repeated, in different terms. no i don't care. :p)... could it be possible that an object (point A) would remain stationary in terms of relative space, while another object actually moved 'away' at a speed faster than light? Not two objects moving away from each other, but one object moving away from the other, 'on its own', so to speak.
The expansion of space itself, on many levels, at this current point in time, breaks just about every theory we have established, and while 'proving' a few, doesn't help any situation. It completely shatters our elementary understanding of what it is we occupy. So to say we have an absolute grip of astrophysical laws is really perplexing, when we haven't physically observed or proven many of the ones we've established. Most are very well grounded and while nearly impossible to physically prove, observed evidence helps establish those 'rules'. But others, are beyond being pegged 'scientific theories' and are strictly 'theories', because while astrophysicists and mathematicians think they are grand rules, we really don't have the depth and physically observed evidence that would paint the picture clearly.


No because the emitted photons from b would never reach A, IIRC. Then again, I don't know.
 

destrekor

Lifer
Nov 18, 2005
28,799
359
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Originally posted by: Vic
Originally posted by: silverpig
Originally posted by: Vic
Originally posted by: Analog
Interesting. However, they claim some galaxies are moving away from us at greater than the speed of light. I thought that to be impossible.

http://www.youtube.com/watch?v=oAVjF_7ensg

The combined speeds are greater than the speed of light. We're moving too. :)

That's not why... It's because of that plus the expansion of space in between us :)

I addressed that in my 2nd post in this thread :)

If the universe is expanding through time at or near the speed of light, then space must necessarily be expanding at an even faster rate.

isn't space within the universe? if the universe is expanding, then space must be expanding. space is within the universe, at least according to everything regarding the cosmic microwave background. To say there is space outside of the universe, that must be expanding to allow the space within the universe to expand, thus allowing the universe to expand, is a rather mind boggling preposition, not to mention requires some kind of theory and mathematical backing to even provide a clue as to what this extra-universal-space would mean in relation to the space related to the universe.

I kind of hurt my brain with that one. I have to stop, astronomy is a major interest but my brain can only handle so much at any one time. :D
 

Vic

Elite Member
Jun 12, 2001
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Uh... I didn't say there was any space outside the universe. :confused:
 

destrekor

Lifer
Nov 18, 2005
28,799
359
126
Originally posted by: RESmonkey
Originally posted by: destrekor
Originally posted by: silverpig
Originally posted by: Analog
Interesting. However, they claim some galaxies are moving away from us at greater than the speed of light. I thought that to be impossible.

http://www.youtube.com/watch?v=oAVjF_7ensg

It's impossible to have a relative velocity greater than light in space yes, but space is expanding.

that poses an interesting, mind-boggling question:

while nothing can move faster than the speed of light in space, can the expansion of space cause matter to move faster than light?

While it makes sense that two objects moving away from each other, when viewed from one object, would represent movement at faster than light (point a looking at point b, both moving away, by observing from point a makes point b appear to move faster than light away from point a. yes i just repeated, in different terms. no i don't care. :p)... could it be possible that an object (point A) would remain stationary in terms of relative space, while another object actually moved 'away' at a speed faster than light? Not two objects moving away from each other, but one object moving away from the other, 'on its own', so to speak.
The expansion of space itself, on many levels, at this current point in time, breaks just about every theory we have established, and while 'proving' a few, doesn't help any situation. It completely shatters our elementary understanding of what it is we occupy. So to say we have an absolute grip of astrophysical laws is really perplexing, when we haven't physically observed or proven many of the ones we've established. Most are very well grounded and while nearly impossible to physically prove, observed evidence helps establish those 'rules'. But others, are beyond being pegged 'scientific theories' and are strictly 'theories', because while astrophysicists and mathematicians think they are grand rules, we really don't have the depth and physically observed evidence that would paint the picture clearly.


No because the emitted photons from b would never reach A, IIRC. Then again, I don't know.

Wouldn't it just take longer?

Think of it like a speed limit. Say light can only go 60mph, but two cars are moving in opposite directions at 35mph each. Say it takes one year from the two positions the cars at at for light to reach each other. If they then started moving apart, and Car A began flashing a light at Car B... hmm this is going to require math. I give up. :laugh: But wouldn't Car A's light reach Car B at some point, since both objects on their own are actually moving far less than the speed of light? Their might be a growing distance in between the two, but that's just distance.

The way I look at it, it's not as if light is constantly pulled by the one object moving to the rear of it. At the moment Car A flashes the light, we can immediately forget about Car A, and now focus on the light, which is now moving toward Car B at 60mph, from whatever point in space, while Car B, some years away, is moving forward at barely over half that speed. Eventually the light will catch up.
 

destrekor

Lifer
Nov 18, 2005
28,799
359
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Originally posted by: Vic
Uh... I didn't say there was any space outside the universe. :confused:

hmm, maybe I read that wrong.

The way you worded it, it made it sound like you were saying the expansion of the universe requires the expansion of space. That seems to add a greatly unnecessary level of complication, because the expansion of the universe IS technically the expansion of space.

Yet, in another light, they are greatly different. The expansion of the universe really just means everything within the universe, all the galaxies, move further away from one another. Thus, space in between the universal bodies expands. But, one way of interpreting the phrase "the expansion of space", and only that phrase, could mean that all of space, even the space within galaxies, would expand. This would most definitely result in the heat death of the universe, but in the end that cannot happen, because all the objects in a galaxy are orbitally tied to one another, the space in between two orbiting bodies should theoretically never expand unless the orbit is not a stable orbit (most bodies are going to drift, in barely comprehensible terms, over time. i.e. our moon is drifting away from us, but notably, this is not a stable orbit. never was, just appears that way when looking from a great distance).

So to make this short, instead of repeating myself in different styles like I eventually always do, space and the universe, in terms of expansion, and essentially the same, so adding unnecessary levels just confuses people, like myself. ;)
 

BUTCH1

Lifer
Jul 15, 2000
20,433
1,769
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Originally posted by: Vic
Uh... I didn't say there was any space outside the universe. :confused:

Wow, awesome, thanks OP. This begs the question though, If I was in a car traveling at the speed of light and turned on my headlights, what would happen??.