Celestia Forums

I've got a question.

Someone in another topic mentioned briefly that we're seeing the crab nebula as it were 6300 years ago. I'm well aware of all of that, how we see objects as they were in the past, but it made me think of a question.

If you were in a spacecraft traveling very fast towards the crab nebula, would you see a sort of "flip-book" or time-lapse photography kind of effect, such as that you'd rapidly see it more and more towards the state it's in today?

I don't think I phrased that very well, it's late and I've just woken up from a nap.

If I were to give you an oversimplified answer, it would be yes.

1) Remember though, that as your speed approaches light speed, your mass approaches infinity, your size approaches 0 (Lorentz contraction), and thus your desnity approaches infinity. Also your local time would appear to have stopped to us.

2) As you approach light speed, looking ahead of you, everything you see would appear to get closer to direction of travel (i.e. everything would bunch up infront of you). This is cauesd by the different angle that the light is reacing you. Also, everything would be blue-shifted quite a bit.

To see the crab nebula go backwards, you would have to move faster than light, which is forbidden by Einstein, and illegal by the Constitution of Turkministan. Einstein himself will personally hunt you down and slap you for even trying. So I would suggest not attempting it.

Now if you want to use an alcubierre drive (which is of course, purely theoretical), you could move faster than light relative to the surrounding space time (stopped relative to local spacetime). Then you would just have problems I mentioned in the second paragraph (labled with a nifty "2").

Stellatus wrote:I've got a question.

Someone in another topic mentioned briefly that we're seeing the crab nebula as it were 6300 years ago. I'm well aware of all of that, how we see objects as they were in the past, but it made me think of a question.

If you were in a spacecraft traveling very fast towards the crab nebula, would you see a sort of "flip-book" or time-lapse photography kind of effect, such as that you'd rapidly see it more and more towards the state it's in today?

I don't think I phrased that very well, it's late and I've just woken up from a nap.

All the fancy speed-of-light science aside - Considering that a nebula could be the after affect of an explosion, or a result of gravitational collapse, or some phase inbetween both... I would think if you sped towards it at "light-speed" you'd see a preview of it's future appearance (as opposed to standing here on Earth waiting for the light to arrive here for us to see it) with it either growing in size as it expanded outward, or shrinking inward as it collapsed.

I wonder (Physics and Einstien's retribution aside),
If you came FROM somewhere far away, and traveled well past the speed of light, could you look backward and see yourself coming?

Tuefish wrote:I wonder (Physics and Einstien's retribution aside),
If you came FROM somewhere far away, and traveled well past the speed of light, could you look backward and see yourself coming?

Ignoring all the physics, yes. But since we're ingoring all the physics... in reality: no.

Tuefish wrote:I wonder (Physics and Einstien's retribution aside),
If you came FROM somewhere far away, and traveled well past the speed of light, could you look backward and see yourself coming?

How can you ignore all the Physics in a thread called "Physics and Astronomy"? Given the premises of this thread, your question doesn't make sense at all.


Also this Mr. is called Einstein . What is "Einstien's retribution"??

Bye Fridger

t00fri wrote:What is "Einstien's retribution"??

Hungry4info wrote:To see the crab nebula go backwards, you would have to move faster than light, which is forbidden by Einstein, and illegal by the Constitution of Turkministan. Einstein himself will personally hunt you down and slap you for even trying. So I would suggest not attempting it.

Einstein wrote: Try it... I dare you.

If you came FROM somewhere far away, and traveled well past the speed of light, could you look backward and see yourself coming?

...except that these TV guys don't know ANY physics and instead "infect" innocent people with nonsense...

Bye Fridger

t00fri wrote:...except that these TV guys don't know ANY physics and instead "infect" innocent people with nonsense...

Bye Fridger

Amen!