Camera near the speed of light

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Discussion Overview

The discussion revolves around the feasibility of taking photographs in scenarios involving speeds approaching the speed of light, particularly focusing on the experiences of individuals on a spaceship and the potential relativistic effects observable from different frames of reference. The conversation explores theoretical implications and the nature of relativity in this context.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that if two people are on a spaceship traveling at near the speed of light, they would be able to take pictures of each other without noticing anything unusual due to their relative rest frame.
  • Others argue that the question of taking pictures at such speeds is moot, as it is impossible to have a spaceship traveling at those speeds in practical terms.
  • A participant points out that relativistic effects would be observable if someone on a passing planet attempted to photograph someone on the spaceship, raising questions about the nature of those effects.
  • There is a discussion about the semantics of "moot" and whether the question can be considered valid if it is theoretically possible to take such photographs.
  • Some participants express uncertainty about the practical significance of thought experiments involving speeds close to light, questioning the relevance of such scenarios.
  • A later reply highlights the importance of understanding that relativistic effects depend on the frame of reference and that velocities do not affect observations within an inertial frame.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the validity of the original question regarding the feasibility of taking photographs at near-light speeds. There are competing views on whether the question is moot or if it holds theoretical significance.

Contextual Notes

Some participants mention the limitations of the discussion, including the dependence on definitions of "moot" and the abstract nature of the scenarios presented. There are unresolved questions about the practical implications of relativistic effects and the conditions under which they might be observed.

Voltaire6022
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If you were infinitely close to the speed of light, and you attempted to take a picture of yourself, would it work? Would there be any way to make it work using relative velocities?
 
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What? Structure the question better.
 
Say two people are on a spaceship traveling at near speed of light. If one wants to take a picture of the other, would that be possible?

EDIT: The picture would be taken by the person in the rear of the craft, facing the front.
 
They shouldn't see nor feel anything strange, assuming they are moving with constant, uniform velocity (with respect to some other observer, of course - in their frame they are stationary). So yes, they will be able to take a picture.
 
Yes, if they are both on the same spaceship traveling at near the speed of light, they would be able to take pictures easily. They wouldn't even notice anything strange because relative to each other, both of them are at rest.

The spaceship traveling near the speed of light must be traveling at that speed relative to something else, and it certainly isn't traveling at that speed relative to the people inside of it. You would have to say the spaceship is traveling near the speed of light relative to say, a passing planet or star or whatever. And even then, on board, nothing peculiar will happen.

The interesting question, on the other hand, would be if someone on a passing planet tried to take a picture of someone on the spaceship, then you'd see relativistic effects!
 
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Much less exciting than what I was hoping, but thanks :P
 
Pengwuino said:
The interesting question, on the other hand, would be if someone on a passing planet tried to take a picture of someone on the spaceship, then you'd see relativistic effects!

That's not an interesting question, especialy not the interesting question.

Yea I bet that photo would turn out real well. :rolleyes:

At speeds "infinitely" close to c, the answer they "wouldn't notice anything different and could take pictures easily" is moot.
 
That is, after all, the whole point of "relativity". The two people are, relative to each other, stationary.
 
nitsuj said:
That's not an interesting question, especialy not the interesting question.

Yea I bet that photo would turn out real well. :rolleyes:

What? You don't think that a photo showing relativistic effects would be interesting?

nitsuj said:
At speeds "infinitely" close to c, the answer they "wouldn't notice anything different and could take pictures easily" is moot.

That doesn't really make any sense. That IS the answer - how can it be "moot?"
 
  • #10
elfmotat said:
What? You don't think that a photo showing relativistic effects would be interesting?



That doesn't really make any sense. That IS the answer - how can it be "moot?"


Never said I don't think that a photo showing relativistic effects would be interesting.

I said that it is not an interesting question, let alone, the interesting question.

it is not possible so that makes it moot.
 
  • #11
nitsuj said:
it is not possible so that makes it moot.

In principle it is possible, so the question is not moot.
 
  • #12
nitsuj said:
Never said I don't think that a photo showing relativistic effects would be interesting.

I said that it is not an interesting question, let alone, the interesting question.

it is not possible so that makes it moot.

Why is it not possible? In a sense that's what astronomy is all about... although maybe the things they see are more often GR effects than SR ones
 
  • #13
elfmotat said:
In principle it is possible, so the question is not moot.

I think there may be a semantic issue here. If you had a photo that showed effects depending on "velocity through space" or "absolute velocity", they wouldn't be relativistic effects. They'd be evidence that relativity was wrong.

Note that we (or at least I) don't want to start a debate on "is relativity right or wrong" here. The experimental evidence is out there for those who want to study it (such as the failure of previous attempts to measure the absolute velocity of the Earth through space through the M.M. experiment, for starters).

The forum is mostly dedicated to helping people who want to understand relativity to understand it. And part of understanding relativity is understanding that things don't look any different depending on your velocity, this is one of the fundamental principles.
 
  • #14
pervect said:
I think there may be a semantic issue here. If you had a photo that showed effects depending on "velocity through space" or "absolute velocity", they wouldn't be relativistic effects. They'd be evidence that relativity was wrong.

Note that we (or at least I) don't want to start a debate on "is relativity right or wrong" here. The experimental evidence is out there for those who want to study it (such as the failure of previous attempts to measure the absolute velocity of the Earth through space through the M.M. experiment, for starters).

The forum is mostly dedicated to helping people who want to understand relativity to understand it. And part of understanding relativity is understanding that things don't look any different depending on your velocity, this is one of the fundamental principles.

I think you may have misunderstood what nitsuj was saying. He wasn't arguing that photographs taken in an inertial reference frame near traveling near c relative to another observer wouldn't show relativistic effects within that frame - he was arguing that it's impossible to have a spaceship traveling near c to begin with, so the question is moot. If you read my original post in this thread you'll see that I'm well aware of the principle of relativity.
 
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  • #15
elfmotat said:
I think you may have misunderstood what nitsuj was saying. He wasn't arguing that photographs taken in an inertial reference frame near traveling near c relative to another observer wouldn't show relativistic effects within that frame - he was arguing that it's impossible to have a spaceship traveling near c to begin with, so the question is moot. If you read my original post in this thread you'll see that I'm well aware of the principle of relativity.

I'd like to point out I said specifically the answer is moot.

I never read the definition of moot until now.

http://www.merriam-webster.com/dictionary/moot"

Doesn't make sense? It could define moot.
 
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  • #16
Pengwuino said:
Why is it not possible?

I don't know. Is it?

Is it possible for there to be a ship with two people on board with a camera all traveling "infinitely close to the speed of light" and take a photo?

And at the same time on a planet passed by the ship a camera takes a photo of the ship while it passed by at "infinitely close to the speed of light"?

And that photo to show relativistic effects?

Sounds rather abstract and deprived of practical significance.
 
  • #17
nitsuj said:
I don't know. Is it?

Is it possible for there to be a ship with two people on board with a camera all traveling "infinitely close to the speed of light" and take a photo?

And at the same time on a planet passed by the ship a camera takes a photo of the ship while it passed by at "infinitely close to the speed of light"?

And that photo to show relativistic effects?

Sounds rather abstract and deprived of practical significance.

Why do you think thought experiments should be limited to the practical? Would you prefer the scenario "say there's a mu-meson particle moving at..." ? I don't really understand what your point is.
 
  • #18
nitsuj said:
I don't know. Is it?

Is it possible for there to be a ship with two people on board with a camera all traveling "infinitely close to the speed of light" and take a photo?

And at the same time on a planet passed by the ship a camera takes a photo of the ship while it passed by at "infinitely close to the speed of light"?

And that photo to show relativistic effects?

Sounds rather abstract and deprived of practical significance.

Yes, but that's like saying "what if I had a fusion powered rocket strapped to a 9 headed alien who eats glue and mates with cows. A cow attempts to take a picture of this fusion powered alien from Earth as it flies by...". These abstract concepts are simply human methods of imagining what is going on. Just because the description is not practical or possibly even silly doesn't mean we can't use it to understand what is actually happening in the universe. We just know that instead of a 9 headed alien traveling by Earth, we have a proton slamming into a target in a high energy physics experiment.
 
  • #19
elfmotat said:
I don't really understand what your point is.

Here is the OP's question

"Say two people are on a spaceship traveling at near speed of light. If one wants to take a picture of the other, would that be possible?

EDIT: The picture would be taken by the person in the rear of the craft, facing the front."

After givin a moot answer...

The OP left with "Much less exciting than what I was hoping, but thanks :P".

So the OP belives a photo can be taken at near c speeds on a spaceship.

Perhaps the OP would have found it even less exciting to hear the impossibilities of accelerating a spaceship with people on board to near c speeds.
 
  • #20
nitsuj said:
So the OP belives a photo can be taken at near c speeds on a spaceship.

And rightfully so, because a photo CAN be taken at speeds near c on a spaceship - whether or not we can build such a spaceship is irrelevant. OP's question was about the principle, and he was given an answer. I'm starting to think you're trolling me...
 
  • #21
Justin, this is a question of principle. There is absolutely nothing in principle stopping the scenario from occurring.

Consider another question:
"Is it possible to take a picture on Pluto?"
Justin: "It is moot since we cannot get to Pluto."
Everyone else: "Of course it is possible to take a picture on Pluto."

Now, on to what would happen in the spaceship:

If we were to accelerate arbitrarily close to the speed of light, inside our spaceship it would be as if we were utterly stationary. There is no reason why a picture would not be completely normal.

Now, if we looked out the window, we'd see the universe whizzing by incredibly foreshortened and red/blue-shifted, but that's something else.
 
  • #22
DaveC426913 said:
Justin, this is a question of principle. There is absolutely nothing in principle stopping the scenario from occurring.

Consider another question:
"Is it possible to take a picture on Pluto?"
Justin: "It is moot since we cannot get to Pluto."
Everyone else: "Of course it is possible to take a picture on Pluto."

Well Said Dave! I see their perspective more clearly now.
 
  • #23
Note, there are 'observers' who see the space station and its occupants moving at 'virtually the speed of light'. They are called cosmic rays. Just as valid a frame as any other. Outfitting them with cameras is a bit of problem ...
 
  • #24
This may be a stupid question but since this thread is about taking pictures while traveling near c, relative to let's say the earth. What would a picture taken looking out the side window look like. Assuming the lense of the camera was perfectly perpendicular to the direction of travel, and what would the picture look like out of the front and rear windows?

I'm going to take an uneducated guess and say everything out of the front window would be more blue, and the rear window more red. But would the length contraction be noticable? and would the length elongate out of the back window?
 
  • #25
tkav1980 said:
This may be a stupid question but since this thread is about taking pictures while traveling near c, relative to let's say the earth. What would a picture taken looking out the side window look like. Assuming the lense of the camera was perfectly perpendicular to the direction of travel, and what would the picture look like out of the front and rear windows?

I'm going to take an uneducated guess and say everything out of the front window would be more blue, and the rear window more red. But would the length contraction be noticable? and would the length elongate out of the back window?

 
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  • #26
elfmotat said:


Verry cool. Thank you for that!
 
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  • #27
elfmotat said:


Way cool video.

Also: awesome avator elfmotat.
 
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  • #28
Consider this. Objects very distant from the Earth are observed to have velocities near the speed of light with respect to earth. So with respect to these distant objects the Earth is traveling at a relativistic velocity.

Now, can you take a picture?
 
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  • #29
Integral said:
Consider this. Objects very distant from the Earth are observed to have velocities near the speed of light with respect to earth. So with respect to these distant objects the Earth is traveling at a relativistic velocity.

Now, can you take a picture?

Well Since we have some pictures of verry distant galaxys I'll say yes.

This may be the wrong part of the forum for this question, but I read on Discovery channel's website that some of the most distant ones are photographed using gravitational lensing. After watching that animation linked a few posts above, how does that effect change the picture?

Sorry if my answers are...well dumb...I don't possesses the math skills to really analize this type of thing so I am really just guessing based off of what I've seen and read.
 
  • #30
tkav1980 said:
Well Since we have some pictures of verry distant galaxys I'll say yes.
Correct.

But the other point being: since from their point of view it is us speeding through the universe at near c, and we don't have trouble taking picture of each other here on Earth... therefore moving at near c does not affect the ability to take pictures.

tkav1980 said:
This may be the wrong part of the forum for this question, but I read on Discovery channel's website that some of the most distant ones are photographed using gravitational lensing. After watching that animation linked a few posts above, how does that effect change the picture?
This is unrelated. Grav lensing simply distorts the image:
220px-2004-08-a-web_print.jpg

Wiki gravitational lens for more info.
 

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