Question about light speed (crappy ms-paint graphic included)

[blike]

In frames A and B we see the starship enterprise travling at 0.8c and shooting an ultra-powerful planet-destroying super burninating ray gun at a giant space-mirror.

 

Frame A is from the viewpoint of the people inside the Enterprise (I know I know, its third person, but I didn't feel like making the view from inside the starship).

 

Frame B is the viewpoint from stationary people watching the starship fly by at near luminous speeds.

 

From what I've read, no matter how fast you're travling, light will always travel at c relative to you. So if you were inside the enterprise, light would be traveling at c away from you.

 

Now, wouldn't this pose a physical problem between observations of the people outside and the people in?

 

The stationary people watching the enterprise fly by (FRAME B) will see the light traveling not too far in front of the starship and not yet hitting the mirror...

 

However, the people inside the starship would see the light beam shoot out at luminous speeds in front of the starship and hence, they would observe it hit the mirror before the people outside the starship would (FRAME A).

 

Whats the deal?

[Radical Edward]

no problem with it at all.

 

actually one of the ways to derive length contraction and so on is to use exactly this sort of approach.

 

incidentally, ms paint drawings are 1337.

[Ryoken]

This sort of stuff is interesting, I understand how that is correct but it dosn't stay with me.

 

Time becomes more viscous as c is approached, is a good way of thinking of it, i think.

[blike]

Ok, what happens in this case (frame description same as original post). The only difference is that the light is bouncing off the mirror, onto a stationary observer and returning information to the ship about the observer. This all happens before the observer even knows the light is going to hit him...

 

Is this is a way to collect data about something without actually distrubing it in ANY way?? By the time the light the space-man (from his point of view), the space-ship already has gathered information about him information without distrubing him...

[Sayonara]

Ummm... firing a phaser into someone's head isn't exactly 'not disturbing' them.

 

But you're right Blike, this is a fascinating area. I think it mainly creates problems because most humans try to process cause-effect systems in a logical pattern, but relativity has a way of introducing parallel logicisms.

 

Or does that make no sense?

[blike]

Would this be a theoretical form of interaction-free measurement?

[blike]

Alright alright, last illustration

 

Let's say in frame A, the people in the enterprise see the laser project at C (relative to its motion), bounce off the mirror, split mr. outside observer's body (ignore the part about it returning to the ship). The ship then beams a message to the observer's (now split body) telling him to DUUCKK!!

 

From the observer's point of view, the laser has not yet reached his body. He receives the message to duck and does so before the laser reaches him (travling at C, relative to his stationary position).

 

Now we have a problem. The spaceship people see him dead, yet he's still alive from his POV.

 

Whats the deal?

[Radical Edward]

again, you have to stick it into the equations, so it takes care of all the time dilation and length contraction effects... I can't do it intuitively unfortunately, but it isn't too hard one of the beauties of SR, and GR I suppose, is that it doesn't actually generate any paradoxes at all.

[Ryoken]

Blike, but in your example there the 'DUCK!' message seems to travel faster than the speed of light in order to reach the person before the actual (on the observer's time frame) phazer hits him.

 

I guess practice makes perfect in things.

 

I don't see any problems in what you just proposed there... or maybee my understanding is just flawed. :dunno:

[blike]

Originally posted by Ryoken

Blike, but in your example there the 'DUCK!' message seems to travel faster than the speed of light in order to reach the person before the actual (on the observer's time frame) phazer hits him.

 

I guess practice makes perfect in things.

 

I don't see any problems in what you just proposed there... or maybee my understanding is just flawed. :dunno:

 

Assume the space ship is passing right in front of the observer when it sends the message. The laser beam must travel all the way out to the mirror and bounce back to the observer. The "DUCK!" message only has to travel from the ship in a straight line to the observer.

[Tom Mattson]

I had a post explaining why your situation is impossible, but then I saw the picture.

 

The point is, if the spaceship sees him die, then he dies in every frame. Try playing with the Lorentz transformation for the following:

 

Event 1: Laser fired

Event 2: Message sent

Event 3: Laser hits

Event 4: Message arrives

 

You will certainly be able to construct scenarios in which the message arrives before the laser hits (by making the path length for the laser sufficiently long), but you will never be able to construct an case in which the man dies in one frame and not in another.

 

Tom

[M-CaTZ]

I can see where you are coming from in terms of theory of relativity, and how the ship sees it before the person, however i must say, personally i dont believe in that theory, because it deifes logic. I understand it has been proven, however i dont believe it can pertain to all circumstances, and as we all know logic is the basis of mathematics to begin with. I know this doesnt answer your question but just something to think about:D

[aman]

Because of time dilation, wouldn't a message sent from a ship near light speed be high energy and very compressed?

Maybe a computer could decipher it.

Just aman

[JaKiri]

M-CaTZ said in post #12 :

I can see where you are coming from in terms of theory of relativity, and how the ship sees it before the person, however i must say, personally i dont believe in that theory, because it deifes logic. I understand it has been proven, however i dont believe it can pertain to all circumstances, and as we all know logic is the basis of mathematics to begin with. I know this doesnt answer your question but just something to think about:D

 

Explain Michaelson-Morely and Lorenz Transforms please.

[aman]

I'm trying to take the intuitive approach and when I see a ship travelling near light speed parallel to me at a distance that allows more than a couple of seconds of observation, I need to see the time dilation effects at the same time.

I had it backwards in my last post. A radio communication from me to the ship would seem high energy and compressed to them and a message from them would be red shifted. Still the radio signals would both travel at the speed of light and contain the same total energy as when they originated.

Intuitively then to me observing, a phaser shot into a mirror ahead of the ship would still travel at the speed of light but be less energy and longer duration after it arrives but it would still total the same energy as when it was fired.

Is this close to what would really happen?

Just aman