question (Relativity?) (1 Viewer)

[undalay]

A spaceship is flying away from a satellite at light speed.
A radosignal is sent to the spaceship from the satelitte.
Explain whether the signal will reach the spaceship and any implications.

A radiosingal is then sent from the spaceship to the satellitte.
Explain whether the signal will reach the satelitte and any implications.

edited: thx senrui

 

[Senrui]

"A radiosingal is then sent from the spaceship to the satellitte.
Explain whether the signal will reach the spaceship and any implications."

You mean: "A radiosignal is then sent from the spaceship to the satellite.
Explain whether the signal will reach the satellite and any implications."?

 

[Forbidden.]

Vague explanation.
Most wavelengths of radio is reflected by the ionosphere, severely restricting the range of wavelengths of radio for communication between satellites in space and stations on Earth to a 'window'.
Doesn't have much to do with relativity.

 

[undalay]

satelitte = out of ionosphere?

 

[kooltrainer]

it will reach the satellite because of special theory of relativity

 

[uberturtle]

It travels through aether. gg.
hahaha

situation #1: Satellite to spaceship.
assuming the spaceship sets off first and is travelling at a constant rate of 3x10^8
then the radio signal is sent after it also travelling at 3x10^8. the radio signal will never reach the spaceship because they are both travelling at the same velocity, however the spaceship started its journey first so it will always be a certain distance ahead of the radio signal.


situation #2: Spaceship to satellite.
since the satellite has such a low velocity compared to the space ship it will be observed as stationary or travelling really slowly from the satellite so any radio signal sent to the satellite would reach it.


i'm not sure if these are correct ~_~ but im not einstein either. im just an average 40 year old paedo ):

 

[Steth0scope]

I find it hard to believe that the spaceship can travel at the speed of light. The reason for this is that as the ship reaches the speed of light, according to special relativity, its mass dilates (i.e. it gets heavier). The closer it gets to the speed of light, the more massive the spaceship gets. The more massive the spaceship gets, the more energy it requires to maintain a constant speed anywhere near the speed of light. This means that as the spaceship increases its velocity anywhere near the value of c, it requires an INFINITE amount of energy to maintain it, but this can never be achieved i.e. the spaceship can't reach the speed of light.

Hence, by proving that the spaceship can't travel at the speed of light, and knowing that any radiated e.m.r. photons from the satellite travel at the speed of light, the photons will eventually reach the spaceship.

Ask a stupid question, get a stupid answer. (jk)

 

[uberturtle]

Theoretically speaking!

Nothing with mass will be able to travel at the speed of light due to the infinite energy force thingo

and

time dilates as an objects velocity approaches c so time would stop or travel very very very very slowly so you cant travel any faster since velocity is dependant on time as well

 

[undalay]

situation #1: Satellite to spaceship.
assuming the spaceship sets off first and is travelling at a constant rate of 3x10^8
then the radio signal is sent after it also travelling at 3x10^8. the radio signal will never reach the spaceship because they are both travelling at the same velocity, however the spaceship started its journey first so it will always be a certain distance ahead of the radio signal.


situation #2: Spaceship to satellite.
since the satellite has such a low velocity compared to the space ship it will be observed as stationary or travelling really slowly from the satellite so any radio signal sent to the satellite would reach it.
quote]

Situation #1:
So from the satellites P.O.V the radiosignal and spaceship are stationary relative to each other, thus it won't reach.
But from the spaceships P.O.V, the radiosignal is moving at lightspeed towards the ship (since speed of light in constant). So the signal WILL reach??????

 

[kooltrainer]

i think it will reach the spaceship for situation one because of special theory of relativity . stop trying to disprove it god damit!

 

[jcurry]

I find it hard to believe that the spaceship can travel at the speed of light. The reason for this is that as the ship reaches the speed of light, according to special relativity, its mass dilates (i.e. it gets heavier). The closer it gets to the speed of light, the more massive the spaceship gets. The more massive the spaceship gets, the more energy it requires to maintain a constant speed anywhere near the speed of light. This means that as the spaceship increases its velocity anywhere near the value of c, it requires an INFINITE amount of energy to maintain it, but this can never be achieved i.e. the spaceship can't reach the speed of light.

Hence, by proving that the spaceship can't travel at the speed of light, and knowing that any radiated e.m.r. photons from the satellite travel at the speed of light, the photons will eventually reach the spaceship.

Ask a stupid question, get a stupid answer. (jk)

its called a thought experiment where you are allowed to travel at the speed of light

 

[Steth0scope]

its called a thought experiment where you are allowed to travel at the speed of light

Umm its called shut the f up because c is the speed limit of universe.

 

[uberturtle]

Umm its called shut the f up because c is the speed limit of universe.

no its not.
electric pulses that stimulate your mind are faster than light buddy

 

[Steth0scope]

no its not.
electric pulses that stimulate your mind are faster than light buddy

Um, are we talking about spaceships or electric pulses here?

 

[Forbidden.]

no its not.
electric pulses that stimulate your mind are faster than light buddy

So you are saying that a negatively charged particle that has a mass is capable of traveling faster than the speed of light neglecting mass dilation despite having mass ?

 

[bachinaminuet]

I think that the question is silly because as markzada says itis impossible to reach the speed of light when an object has mass. Even though it is a thought experiment, they have to limitations also. Anyway, in both situations the radio wave will reach the other ship/satellite because otherwise it is breaking the law that light is a constant and therefore removing the theory of special relativity.

Situation1: the radio wave will reach the space ship because if it didn't reach the spaceship, an observer in the spaceship would measure the speed of light to be different to the constant speed of 3 x 10^8m/s. This would violate the theory and therefore all of special relativity would be incorrect. So this means that it has to reach the spaceship. The implications that it would arise however, is that the observer in the space ship will never the observer in the satellite send out a radio frequency because if the spaceship is traveling at the speed of light then time will stop. So it will reach the spaceship, but it will take infinity to reach it. This is the problem with conducting thought experiments when the mass objects are travelling at the speed of light, it is impossible. So the short answer is it will reach the space ship, but it will take infinity to reach it.

However, if the experiment was conducted at 0.99c then the radiowave will reach the spaceship within a certain time. c will be constant, accepting the theory, time will highly dilated so it will reach the spaceship.

Situation 2: because of relative motion it will be the same ordeal.

Here is something to mess with people's heads. If we take the example of the rocket ship speeding away from me at the speed of light, if it went from stationary to the speed ofl light instantly, then the rocket would appear to be not moving, to be stationary, but it is actually travelling at the speed of light. If you put velocity into the time dilation equation as "c", then you get zero on the bottom. This means that it will take infinity time to actually move, in my frame of reference, but inside the space ship, he is miles away. That is pretty trippy!!!

 

[undalay]

i think this is equivalent of the twin's paradox.
Both are correct and contradict eachoter.

 

[bachinaminuet]

I don't think it is part of the twins paradox because the spaceship is not accelerating, it is in an inertial frame of reference at the speed of light. The twins paradox only happens in an non-inertial frame of reference. It is just part of the special relativity.

I actually gave it more thought and realised the ship would be in front of you but only the back of the ship was there. Because if the ship instantly reached the speed of light in front of me (completely hypothetical) after both of us were stationary, then the ship would appear to have not moved from in front of me in my stationary frame. HOwever, really it is 186000 miles away, however the ship would not exist because the length would have gone to zero in the parts that were traveling parallel to the direction of motion. So it would be 2D image in front of me, it would have not moved because time would have stood still for the ship in frame of reference so it would take infinity to move, It would have an infinite mass and therefore an infinite gravitational field. This would, i think, would tear a hole in space time and suck all light into it and nothing would exist, but only in my frame of reference. So therefore the spaceship is sort of traveling into a black hole that only appears to be there in my frame of reference. I give these things to much thought...lol

 

[undalay]

I don't think it is part of the twins paradox because the spaceship is not accelerating, it is in an inertial frame of reference at the speed of light. The twins paradox only happens in an non-inertial frame of reference. It is just part of the special relativity.

Twins paradox only happens in inertial frame of reference.

 

[namburger]

whats twins paradox and do we need to know?