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# Faster Than light

Tue 26 Jan, 2016 06:42 am
Hello
So i was talking with a friend and a one of us asked this question.
if i run faster than light (let's say from earth to the moon) and the stop and look behind me. Will i see myself standing on earth and then disappearing or will i see my self running my way ?
Ps assuming that we won't create any blackholes and my eyes can see any point in the universe
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Type: Question • Score: 9 • Views: 3,448 • Replies: 34

McGentrix

3
Tue 26 Jan, 2016 07:21 am
@Magico-Pancake,
No. You can't run faster then light.
0 Replies

engineer

2
Tue 26 Jan, 2016 07:24 am
@Magico-Pancake,
Let's start with you are running very close to the speed of light. My guess (and there are some real physics folks on here who will have better guesses than me) is that the Doppler effect will shift the wavelengths of light coming off of you to the point where you would not be visible at all. I wonder if, as you approach light speed, if you would become just a bright burst of radiation to the casual observer.
Magico-Pancake

1
Tue 26 Jan, 2016 08:06 am
@engineer,
0 Replies

maxdancona

1
Tue 26 Jan, 2016 08:18 am
@engineer,
The important principle here is relativity.

If you look at another galaxy, let's say galaxy M86, you will say that they are moving at near the speed of light. You make the assumption that our galaxy isn't moving.

Phlegbutzx in galaxy M86 is looking at us and saying that we are the ones moving at near the speed of light. Of course he is making the assumption that his galaxy isn't moving.

So the simple answer is this. Someone in a galaxy that we measure moving near the speed of light will see exactly what we see (since to them we are the ones moving at near the speed of light).
engineer

1
Tue 26 Jan, 2016 08:24 am
@maxdancona,
Ok, but to the original question, if someone were to approach you at near the speed of light, what would they look like to you? It seems like you would get a sonic boom like effect where all the energy emitted at various points in the trip would arrive at almost the same time to the observer.
maxdancona

1
Tue 26 Jan, 2016 08:59 am
@engineer,
You don't get a sonic boom until an object is actually moving faster than the speed of sound (in whatever medium). Travelling at a speed near the speed of sound doesn't do it.

There is an analogue to a sonic boom for light in which particles travel faster than the speed of light for that medium (remember that light propagates slower through matter than it does through a vacuum).

This might interest you...

engineer

1
Tue 26 Jan, 2016 09:14 am
@maxdancona,
Perfect. Thanks for the article.
0 Replies

dalehileman

-2
Tue 26 Jan, 2016 12:38 pm
@Magico-Pancake,
...entailing some very interesting puzzles and contradictions upon which the relativists have been notably silent. Supposedly if you could instantaneously achieve c, to you at the moment of takeoff the rest of the Universe comes to a halt

If that were the case, however, supposedly at that very instant coming back from the opposite direction, you'd see me and yourself at the moment of takeoff

Yet to me, your clock having stopped, if I could live that long it isn't 'til quadrillions of years later I see you returning

Unless of course the Universe is infinite, in which case I'd never see you again; so could only speculate upon whether I'm aging. However infinity is very unlikely for various reasons

So to rescue relativity it's been suggested that when you reach the halfway point, to you, those trillions of years instantly elapse back home; for some reason a somewhat uncomfortable idea
farmerman

3
Tue 26 Jan, 2016 02:40 pm
@dalehileman,
yes but what is the speed of DARK?
dalehileman

0
Tue 26 Jan, 2016 03:17 pm
@farmerman,
Apparently Man, same as light

0 Replies

Setanta

3
Tue 26 Jan, 2016 04:09 pm
@Magico-Pancake,
No, if you attain light speed, your sorry @ss will vanish in a thermonuclear explosion. Bye bye . . .
0 Replies

layman

0
Wed 27 Jan, 2016 07:50 am
When you reach the speed of light, time stops, distances shrink to nuthin, and your mass becomes infinite.

So, then, even though you're fatter than a trillion hogs, you can still travel clean across the universe in nuthin flat, see?

I mean, like, if ya wanna believe that, anyway.
dalehileman

-1
Wed 27 Jan, 2016 11:39 am
@layman,
Still, Lay, assuming a finite cosmos, proceeding at close to c in that "straight line," let's say you make each return trip (to you) in 1 microsecond. The q before the hose is whether--assumng I can live forever--every usec you find me having aged quadrillions of additional years--in which case of course my time hadn't really stopped

Even Albert tacitly admitted that the Twin Paradox hasn't really been resolved
farmerman

2
Wed 27 Jan, 2016 05:25 pm
@dalehileman,
what about at the e horizon of a black hole. Whats the speed of dark there?
dalehileman

0
Wed 27 Jan, 2016 07:04 pm
@farmerman,
Man, good q
0 Replies

neologist

1
Wed 27 Jan, 2016 09:52 pm
@farmerman,
farmerman wrote:
yes but what is the speed of DARK?
Dark is gone as soon as I open the closet door.
So.
Dark is zippy.
0 Replies

Finn dAbuzz

2
Fri 29 Jan, 2016 10:32 am
@farmerman,
farmerman wrote:

yes but what is the speed of DARK?

A fan of Steven Wright?
farmerman

1
Fri 29 Jan, 2016 08:09 pm
@Finn dAbuzz,
I was wondering when somebody would catch on?

"One of my favorites was Wright

"Say youre driving along at the speed of light and you turn on your headlights--does anything happen?"
dalehileman

0
Sat 30 Jan, 2016 01:18 pm
@farmerman,
Quote:
I feel compelled to explain for the benefit of the casual visitor not familiar with Albert's assertions, that of course the relativist will reply that you can't be traveling at quite c, no matter how long you've been accelerating; so to you the beam will seem to exit at c

However I have a crazy alternate theory, which I call "relative relativity" that not only explains that apparent limit of c to the satisfaction of "mind's eye" but also puts the Twin Paradox to bed forever

In short, c is only light's speed apparent to me back on Earth; but you're perfectly justified in observing, "No, Dale, you're wrong about that. Actually your thinking is based on the assumption that at my takeoff, it's also noon on Mars. But I'm perfectly justified in assuming my trip to be instantaneous; that is, that I'm equally justified in the idea that it's 12:05 there

Hence relative relativity. But I bore youall

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