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# Speed of Light?

ThreeRight
It is said that an object cant move at a speed of light... but this makes no sense since i know that speed is relative.

Example number 1, of man#1 runs in a direction at 5mph, and man#2 runs in the opposite direction at 3mph, to the man#1, it would seem like the man#2 is running away from him at 7mph.

Example number 2, Car#1 is traveling in the speed 50 mph in one direction, and Car#2 is traveling in the speed 65mph and are heading toward each other, so... to the Car#1, the Car#2 would seem to be approaching Car#1 at the speed of 115mph.

so, if an object CANT move at speed of light, whats it relative to? I mean, we are standing on the earth which is spinning, at About 1670 km (1038 mi) per hour. so, relative to earth, we are already moving 1038mph.

Galaxies are speeding apart from each other *(really fast)* and since we are in the milky way, we must also be moving *(really fast)*. Relative to our galaxy...

When one says "you cant move faster then the speed of light" whats it relative to?
marrs
Not really to sure but heres some things to take notice of In 1915 (10 years after special relativity) Einstein developed another theory called General Relativity that deals with gravitational fields and according to this latest theory the velocity of light appears to vary with the intensity of the gravitational field.
To see the steps how Einstein theorized that the speed of light in a gravitational field is actually not a constant, but rather a variable depending upon the reference frame of the observer:
EanofAthenasPrime
uh u gotta learn that light's speed is measurable and that regardless of your motion light will always travel a 3*10^8 ms. This defies common Galilean Relativity.
EanofAthenasPrime
uh u gotta learn that light's speed is measurable and that regardless of your motion light will always travel a 3*10^8 ms. This defies common Galilean Relativity.
Indi
 ThreeRight wrote: It is said that an object cant move at a speed of light... but this makes no sense since i know that speed is relative.

Relative to what? Think about it. How do you know that the speed of light is relative? And what is the speed of light relative to?

 ThreeRight wrote: When one says "you cant move faster then the speed of light" whats it relative to?

If i were to say "i am moving slower than Jim", what am i giving my speed relative to?

Am i not giving my speed relative to... Jim?

So if i say, "i am moving slower than light"... what is it that i am giving my speed relative to?
EanofAthenasPrime
Indi wrote:
 ThreeRight wrote: It is said that an object cant move at a speed of light... but this makes no sense since i know that speed is relative.

Relative to what? Think about it. How do you know that the speed of light is relative? And what is the speed of light relative to?

 ThreeRight wrote: When one says "you cant move faster then the speed of light" whats it relative to?

If i were to say "i am moving slower than Jim", what am i giving my speed relative to?

Am i not giving my speed relative to... Jim?

So if i say, "i am moving slower than light"... what is it that i am giving my speed relative to?

I think you are over complicating things.

I think he just doesn't understand that Light does not follow Galilean Relativity.

Galilean relativity means that two vectors with the same direction can be added together to get an expected sum.

Light does not follow Galilean relativity.

So if a car was moving at you at 50 mph, and you were standing still, and a gunman in the car shot at you with a rifle with a muzzle velocity of 2500 mph, the bullet would move relative to you (and the earth) at 2550 mph (2500+50).
If the car turned on its headlights, according to Galilean relativity, the light should move at c+50 mph. (c=3*10^8m/s)
But in reality, light does not follow Galilean relativity. Light really would travel towards at you at c+Zero.

The reason this happens has much to do with spacetime and Einstien's theories. This we can discuss later.

See light is the ultimate speed. Once you understand the concepts of light you will see how your theory is invalid. True, there is no "special point in the universe" to which we can measure "Absolute Speed"...but even if there was, it wouldn't apply to light since it does not follow Galilean Relativity. It does not matter if you travel at 99.999% the speed of light. If you turned a flashlight on and aimed it in front of you, light would move away from you at the speed of light. It wouldn't move in slow motion.
rshanthakumar
True what you are saying is true of Light! What ever be the instance, light will emanate at the constant speed.

To add to the confusion, there is a rider. When you are travelling at the speed of light, time does not pass. That is because light does not move or you travel with the same ray of light that emanated from the 'change'. Therefore, you never see the 'change' happening or that it never occured to you and therefore time never moves. At near light speeds you should be experiencing the time dilation.

I have my doubts on whether you will see light moving at a slower speed when compared to your own motion if you are travelling at near light speeds. If the light were to maintain its speed even to an observer moving at high speeds then time dilation might not be happening.
EanofAthenasPrime
 rshanthakumar wrote: True what you are saying is true of Light! What ever be the instance, light will emanate at the constant speed. To add to the confusion, there is a rider. When you are travelling at the speed of light, time does not pass. That is because light does not move or you travel with the same ray of light that emanated from the 'change'. Therefore, you never see the 'change' happening or that it never occured to you and therefore time never moves. At near light speeds you should be experiencing the time dilation. I have my doubts on whether you will see light moving at a slower speed when compared to your own motion if you are travelling at near light speeds. If the light were to maintain its speed even to an observer moving at high speeds then time dilation might not be happening.

Uh...You are making things even more complicated.

Three Right please refer to my post above.

rshanthakumar-this is for you:

Please refer to my post above.

ALSO: I am keeping it a secret but I have figured out the Mysteries of Light
And as I said in my above post...light would still move away or towards you at c, even if you were traveling at 99.999999999999% c. Me thinks you should look back into a high school textbook of physics. Also, in that poorly written paragraph (no offense) you constantly contradict yourself? kind of like in Daniel C. Dennets "Consciousness Explained."

About that first paragraph: When you travel at 99% c, time wouldn't go like the Matrix. The only way you would know time is going slower is if you collected external data. For example, you could collect external data by look outside the spaceship window and see the people of Earth walking at 200 mph. So, for many reasons, it is impossible to know what would happen if travelling at 100%c.

If time for you actually stopped, then consciousness would also stop...

Division by 0 errors occur in the time dilation equation

Syntax? errors occur in the time dilation equation

My guess is that if mass travelled at 100%c time would go infinitely fast, and also since the mass travelling at 100%c would be infinite, it would destroy the universe, and thus stop the infinite amount of time that passed from continuing at its infinite rate (since destroying the universe would cause the end of time.)
ThreeRight
 EanofAthenasPrime wrote: It does not matter if you travel at 99.999% the speed of light. If you turned a flashlight on and aimed it in front of you, light would move away from you at the speed of light. It wouldn't move in slow motion.

OF COURSE IT WOULDN'T MOVE IN SLOW MOTION! the light would be moving in the speed of light + "99.999%" of speed of light! so, it would technically be moving in speed of light relative to the flashlight. Since the light would be moving almost 2x the speed of light. people looking with the light thats shot by the flashlight, thats not moving at that speed would see stuff almost 2x faster then regularly because we SEE with light.

 rshanthakumar wrote: True what you are saying is true of Light! What ever be the instance, light will emanate at the constant speed. To add to the confusion, there is a rider. When you are travelling at the speed of light, time does not pass. That is because light does not move or you travel with the same ray of light that emanated from the 'change'. Therefore, you never see the 'change' happening or that it never occured to you and therefore time never moves. At near light speeds you should be experiencing the time dilation. I have my doubts on whether you will see light moving at a slower speed when compared to your own motion if you are travelling at near light speeds. If the light were to maintain its speed even to an observer moving at high speeds then time dilation might not be happening.

it must SEEM like time doesn't pass, but think about this. We as people SEE with light. if a light that bounced off of an object 10 seconds ago enters our retina then we will see what the object WAS 10 seconds ago! if move the same speed as light away from an object and look at the object, the object would seem like its frozen because the light that enters our eyes was bounced away from same time instance. This means that we will SEE the world that we are speeding away from as frozen!

If we move faster then light, then we would SEE the world moving back in time for we would are catching up with the light that started running before us. It wouldn't really be going back or forward in time because its just what we see, not what is...
ThreeRight
ThreeRight wrote:
 EanofAthenasPrime wrote: It does not matter if you travel at 99.999% the speed of light. If you turned a flashlight on and aimed it in front of you, light would move away from you at the speed of light. It wouldn't move in slow motion.

OF COURSE IT WOULDN'T MOVE IN SLOW MOTION! the light would be moving in the speed of light + "99.999%" of speed of light! so, it would technically be moving in speed of light relative to the flashlight. Since the light would be moving almost 2x the speed of light. people looking with the light thats shot by the flashlight, thats not moving at that speed would see stuff almost 2x faster then regularly because we SEE with light.

 rshanthakumar wrote: True what you are saying is true of Light! What ever be the instance, light will emanate at the constant speed. To add to the confusion, there is a rider. When you are travelling at the speed of light, time does not pass. That is because light does not move or you travel with the same ray of light that emanated from the 'change'. Therefore, you never see the 'change' happening or that it never occured to you and therefore time never moves. At near light speeds you should be experiencing the time dilation. I have my doubts on whether you will see light moving at a slower speed when compared to your own motion if you are travelling at near light speeds. If the light were to maintain its speed even to an observer moving at high speeds then time dilation might not be happening.

it must SEEM like time doesn't pass, but think about this. We as people SEE with light. if a light that bounced off of an object 10 seconds ago enters our retina then we will see what the object WAS 10 seconds ago! if move the same speed as light away from an object and look at the object, the object would seem like its frozen because the light that enters our eyes was bounced away from same time instance. This means that we will SEE the world that we are speeding away from as frozen!

If we move faster then light, then we would SEE the world moving back in time for we would are catching up with the light that started running before us. It wouldn't really be going back or forward in time because its just what we see, not what is...

Indi wrote:
 ThreeRight wrote: It is said that an object cant move at a speed of light... but this makes no sense since i know that speed is relative.

Relative to what? Think about it. How do you know that the speed of light is relative? And what is the speed of light relative to?

 ThreeRight wrote: When one says "you cant move faster then the speed of light" whats it relative to?

If i were to say "i am moving slower than Jim", what am i giving my speed relative to?

Am i not giving my speed relative to... Jim?

So if i say, "i am moving slower than light"... what is it that i am giving my speed relative to?

YOU DID NOT READ MY POST!!!

 ThreeRight wrote: When one says "you cant move faster then the speed of light" whats it relative to?

 EanofAthenasPrime wrote: See light is the ultimate speed. Once you understand the concepts of light you will see how your theory is invalid. True, there is no "special point in the universe" to which we can measure "Absolute Speed"...but even if there was, it wouldn't apply to light since it does not follow Galilean Relativity. It does not matter if you travel at 99.999% the speed of light. If you turned a flashlight on and aimed it in front of you, light would move away from you at the speed of light. It wouldn't move in slow motion.

If this is true, then how come when we look up in the sky and see galaxies that are like million light years away, what we are really seeing is what the galaxy was, a million years ago?
if what you say is true, shouldn't it be instantaneous? Shouldn't we be able to see the galaxies as it is happening and not as it WAS happening? when you say "It wouldn't move in slow motion." then of course it wouldnt! light is moving at lightspeed + whatever speed your going!
EanofAthenasPrime
Ean thinks that you should perhaps re-read his post. Ean did not say light is the "infinite" speed. Ean said that light is the "ultimate" speed.

Also, Ean better understands your original post. Now Ean can see the puzzle. Since light always moves the same velocity regardless of the travelers velocity, there is no way to for a traveler to measure their speed in relation to it. However, there is a way for an external viewer to measure it. They would also have to calculate time dilation to get their actual speed as well.

Three Right's second post above is incorrect. A traveller would not see everything as frozen. Three Right, remember that light always travels at the same speed. So light would still take 10 seconds to bounce of that rock regardless of the speed travelled.
polis
C = speed of light

1.- Take a particle p1, and a second particle p2
2.- Put them on an particle accelerator; make them "run" in opposite direction.
3.- trow both of them at C/2 speed, and make them collide.
4.- What you get is a crush at (C/2+C/2) speed, AKA, speed of light.

So, you get two things:
1.- You actually achieve the speed of light
2.- You've just made antimatter for a short while.
polis
 polis wrote: C = speed of light 1.- Take a particle p1, and a second particle p2 2.- Put them on an particle accelerator; make them "run" in opposite direction. 3.- trow both of them at C/2 speed, and make them collide. 4.- What you get is a crush at (C/2+C/2) speed, AKA, speed of light. So, you get two things: 1.- You actually achieve the speed of light 2.- You've just made antimatter for a short while.

This is for real. The CERN did it.

Now, the amazing question is:

what if I trow each at (C/2+1) ?
C+2?

Speed of light overrun?

ThreeRight
 EanofAthenasPrime wrote: Ean thinks that you should perhaps re-read his post. Ean did not say light is the "infinite" speed. Ean said that light is the "ultimate" speed. Three Right's second post above is incorrect. A traveller would not see everything as frozen. Three Right, remember that light always travels at the same speed. So light would still take 10 seconds to bounce of that rock regardless of the speed travelled.

but heres the thing, when you look up into sky, and see galaxies 10 light years away, what you are really seeing is that galaxy as it was 10 years ago right?

lets say you travel away from a planet at light speed for 10 seconds and stop. When you look at the planet, wouldn't what you will really be seeing is what the planet was 10 seconds ago?

USING THIS PRINCIPLE

if you travel away from a planet at light speed and you look back at the planet...

if the instance you look at the planet is 5 seconds after you launched off from the planet at light speed. you would see whatever that happened at the planet 5 seconds ago.

if the instance you look at the planet is 10 second after you launched off from the planet at light speed. you would see whatever that happened at the planet 10 seconds ago...

and since 0+5-5=0 and 0+10-10=0, what you would be seeing is the planet "frozen in time"
Indi
ThreeRight wrote:
Indi wrote:
 ThreeRight wrote: It is said that an object cant move at a speed of light... but this makes no sense since i know that speed is relative.

Relative to what? Think about it. How do you know that the speed of light is relative? And what is the speed of light relative to?

 ThreeRight wrote: When one says "you cant move faster then the speed of light" whats it relative to?

If i were to say "i am moving slower than Jim", what am i giving my speed relative to?

Am i not giving my speed relative to... Jim?

So if i say, "i am moving slower than light"... what is it that i am giving my speed relative to?

YOU DID NOT READ MY POST!!!

 ThreeRight wrote: When one says "you cant move faster then the speed of light" whats it relative to?

Not only did i read your post, i answered your question. If you did not get the answer, a more constructive way to have handled it would have been to ask me to clarify it.

 ThreeRight wrote: but heres the thing, when you look up into sky, and see galaxies 10 light years away, what you are really seeing is that galaxy as it was 10 years ago right? lets say you travel away from a planet at light speed for 10 seconds and stop. When you look at the planet, wouldn't what you will really be seeing is what the planet was 10 seconds ago? USING THIS PRINCIPLE if you travel away from a planet at light speed and you look back at the planet... if the instance you look at the planet is 5 seconds after you launched off from the planet at light speed. you would see whatever that happened at the planet 5 seconds ago. if the instance you look at the planet is 10 second after you launched off from the planet at light speed. you would see whatever that happened at the planet 10 seconds ago... and since 0+5-5=0 and 0+10-10=0, what you would be seeing is the planet "frozen in time"

This is correct. If you were travelling at the speed of light looking backwards, time would appear to stand still.

Now think about what would happen if you looked forward.
ThreeRight
 Indi wrote: Not only did i read your post, i answered your question. If you did not get the answer, a more constructive way to have handled it would have been to ask me to clarify it.

ohh sorry, i re-read the post and i get it now.
so, you cant move faster then "speed of light" relative to the light?

thats really mind-boggling, if one points the flash light in front of oneself, the light coming out of the flashlight would be heading AWAY from the oneself at the "speed of light" but, relative to the light, the one is moving away from the light at the same speed.

so, if one turns on a flash light, and runs in the opposite direction without holding the flashlight in his hands, he would be moving away from the light at the speed faster then the "speed of light" relative to light, wouldn't it?

 Indi wrote: This is correct. If you were travelling at the speed of light looking backwards, time would appear to stand still. Now think about what would happen if you looked forward.

the time would appear to be moving faster? err, it appears like time freezes if you travel @ speed of light and look behind you, but in front of you it would appear that time travels faster... i think... (wow, time is confusing).
rshanthakumar
ThreeRight wrote:
 Indi wrote: Not only did i read your post, i answered your question. If you did not get the answer, a more constructive way to have handled it would have been to ask me to clarify it.

ohh sorry, i re-read the post and i get it now.
so, you cant move faster then "speed of light" relative to the light?

thats really mind-boggling, if one points the flash light in front of oneself, the light coming out of the flashlight would be heading AWAY from the oneself at the "speed of light" but, relative to the light, the one is moving away from the light at the same speed.

so, if one turns on a flash light, and runs in the opposite direction without holding the flashlight in his hands, he would be moving away from the light at the speed faster then the "speed of light" relative to light, wouldn't it?

 Indi wrote: This is correct. If you were travelling at the speed of light looking backwards, time would appear to stand still. Now think about what would happen if you looked forward.

the time would appear to be moving faster? err, it appears like time freezes if you travel @ speed of light and look behind you, but in front of you it would appear that time travels faster... i think... (wow, time is confusing).

Time is confusing because our science linked it with light and particles. Light, in my opinion has very little to do with time. All that light supplies is a constant for our visualisation of time. We should not link this up with time.

Yes, time will 'appear' to stop but it continues to run at both the points. what makes it interesting more is the fact that time is as independent a dimension as any other x, y and z. It will continue to move but our perception could get affected when we move at light speed. There is no other relationship between the two. Even the time dilation is a perception. We might not really be saving time by moving at light speed. We might feel that we are saving. More in line with what happened to Rip van winkle. He still got old.
EanofAthenasPrime
 ThreeRight wrote: USING THIS PRINCIPLE if you travel away from a planet at light speed and you look back at the planet... if the instance you look at the planet is 5 seconds after you launched off from the planet at light speed. you would see whatever that happened at the planet 5 seconds ago. if the instance you look at the planet is 10 second after you launched off from the planet at light speed. you would see whatever that happened at the planet 10 seconds ago... and since 0+5-5=0 and 0+10-10=0, what you would be seeing is the planet "frozen in time"

This seems logical, however, traveling at the speed of light is theoretically impossible as well as undefined, for the sake of discussion this is not provable (the effects of time dilation at lightspeed are unknown).

 Quote: ohh sorry, i re-read the post and i get it now. so, you cant move faster then "speed of light" relative to the light? thats really mind-boggling, if one points the flash light in front of oneself, the light coming out of the flashlight would be heading AWAY from the oneself at the "speed of light" but, relative to the light, the one is moving away from the light at the same speed. so, if one turns on a flash light, and runs in the opposite direction without holding the flashlight in his hands, he would be moving away from the light at the speed faster then the "speed of light" relative to light, wouldn't it? Indi wrote: This is correct. If you were travelling at the speed of light looking backwards, time would appear to stand still. Now think about what would happen if you looked forward.

the time would appear to be moving faster? err, it appears like time freezes if you travel @ speed of light and look behind you, but in front of you it would appear that time travels faster... i think... (wow, time is confusing).

Ean does not understand what your are saying about the flashlight, but you must remember that light is not actually time. Just because light displays time, doesn't mean that not being able to perceive a change in light over time will necessarily affect time. What does affect time is velocity.

 Quote: Time is confusing because our science linked it with light and particles. Light, in my opinion has very little to do with time. All that light supplies is a constant for our visualisation of time. We should not link this up with time. Yes, time will 'appear' to stop but it continues to run at both the points. what makes it interesting more is the fact that time is as independent a dimension as any other x, y and z. It will continue to move but our perception could get affected when we move at light speed. There is no other relationship between the two. Even the time dilation is a perception. We might not really be saving time by moving at light speed. We might feel that we are saving. More in line with what happened to Rip van winkle. He still got old.

Ean agrees with the first paragraph of rshanthakumar's post. However, when moving at speed close to lightspeed, external time speeds up. Time does not go in slow motion. This would defy the laws of matter (our brain would have to be reconfigured for altered consciousness.) So, if you want to skip large amounts of time, high speed travel is for you.
ThreeRight
if external time speeds up, then the people that is looking at the object traveling really fast, is seeing the object moving slow, isn't it? because if external time speeds up, then to the people outside, it would seem as the object has slowed down.

If this is true, then how the heck do we know if the object is traveling really fast, and whats it relative to? relative to the people looking at the object from the outside, it would look like the object is moving slower then it already is. Isn't it true that the time it takes for an object to move from one place to another determines the speed?
EanofAthenasPrime
 ThreeRight wrote: if external time speeds up, then the people that is looking at the object traveling really fast, is seeing the object moving slow, isn't it? because if external time speeds up, then to the people outside, it would seem as the object has slowed down. If this is true, then how the heck do we know if the object is traveling really fast, and whats it relative to? relative to the people looking at the object from the outside, it would look like the object is moving slower then it already is. Isn't it true that the time it takes for an object to move from one place to another determines the speed?

Yes. For example, you could see a digital rendering of a space ship travelling at 99% speed of light (from a distance far enough that it would seem to move slowly.) Then, you could have a real spaceship travelling at 99% with the same distance and vector. The real spaceship would appear to move slower. But that is what the Time Dilation equation is for.
explosive
in nature there is nothing that can be called infinite because this system has 4 diemensions including time and there has to be a begining moment... and there is nothing has a begining can be endless, infinite .
but in space the limit speed is the lights speed. and can be said this speed behaves like infinite because of this this ;300.000 km/sn, the speed of light ,isnt relevant to any speed.. and also because of this time is relative..
ThreeRight
 explosive wrote: in nature there is nothing that can be called infinite because this system has 4 diemensions including time and there has to be a begining moment... and there is nothing has a begining can be endless, infinite . but in space the limit speed is the lights speed. and can be said this speed behaves like infinite because of this this ;300.000 km/sn, the speed of light ,isnt relevant to any speed.. and also because of this time is relative..

but time is just what we use to measure stuff's movement. like, "it took 3 seconds for this object to get from here to there" its just a MEASUREMENT TOOL that man created. Like a ruler stick! "It will take 30 minutes to bake a cake".
------------------------------------------------------------------------
If you get a flash light, point it in front of you and turn it on, Relative to the light that the flashlight is making, you would be moving away from the light at "light speed", so you are basically moving at "light speed" relative to the light that the flash light is making isn't it?.

If thats true then, if you turn on your flash light, and point it in front of you... and run the other way at speed 3mph, Relative to the light that is comming out of the flashlight, you would move the "speed of light" + 3 mph away from the light.

its like, if your standing and your friend runs 4 mph away from you, and your friend looks back.
Relative to your friend, it would look like you and the rest of the world is moving away from him at 4 mph.
explosive
i meant that light speed is independent of the objective that carries it.. Assume a train has a speed of 200.000km/sn a light which send from an edge to another, lights speed is 3 00.000 km/sn for the machinist and also for an observer on earth it is 300.000 too .not 100.000 or 500.000.. so the time will be change for the observers, machinist and the man on world .the time of lights reaching the other edge.
assume again the trains lengt is 300.000 km so the time light must travel this distance , for the machinist light travels this distance 1 sn and for the observer on earth [/u]its speed is also 300.000 but the machine has also a speed relatively the reaching will be occur in 300.000/(300.000+200.000) 0.6 sn
Bikerman
 explosive wrote: i meant that light speed is independent of the objective that carries it.. Assume a train has a speed of 200.000km/sn a light which send from an edge to another, lights speed is 3 00.000 km/sn for the machinist and also for an observer on earth it is 300.000 too .not 100.000 or 500.000.. so the time will be change for the observers, machinist and the man on world .the time of lights reaching the other edge. assume again the trains lengt is 300.000 km so the time light must travel this distance , for the machinist light travels this distance 1 sn and for the observer on earth [/u]its speed is also 300.000 but the machine has also a speed relatively the reaching will be occur in 300.000/(300.000+200.000) 0.6 sn

This is a little unclear. The central point is OK - light travels at the same speed for all observers - but the last paragraph is confusing and I can't see how you get the figures quoted.

Relative time dilation is normally expressed in terms of the Lorentz transformation as follows:

(Where t is time, x,y,z are spatial coords and - which is the Lorentz transformation)
Indi
 ThreeRight wrote: but time is just what we use to measure stuff's movement. like, "it took 3 seconds for this object to get from here to there" its just a MEASUREMENT TOOL that man created. Like a ruler stick! "It will take 30 minutes to bake a cake".

Nothing about relativity denies that time is simply a metric - a measurement. It is a dimension, just like the dimensions of length, width and height. And it's really not that different from those dimensions.

However...

According to relativity, when you measure length, width, height... and time... from different frames of reference, you will get different results. You may say "this object is 2 cm long and took 3 seconds to get from A to B". But if i measure from a different frame of reference, i may find that it is 10 cm long and took 3 years to get from A to B.

 ThreeRight wrote: If you get a flash light, point it in front of you and turn it on, Relative to the light that the flashlight is making, you would be moving away from the light at "light speed", so you are basically moving at "light speed" relative to the light that the flash light is making isn't it?.

Theoretically correct. All of our understanding of time and space breaks down at c, so we can't really wrap our minds around what a photon would "see". But theoretically, the photon would see you moving away at c.

 ThreeRight wrote: If thats true then, if you turn on your flash light, and point it in front of you... and run the other way at speed 3mph, Relative to the light that is comming out of the flashlight, you would move the "speed of light" + 3 mph away from the light.

No, and this is where you have to leave your common sense behind. The light will still leave the flashlight at c... it's just that the photons will be "stretched". The wavelength of the light leaving the flashlight will be "red-shifted" from your point of view, but will still be travelling at c.

But you will still measure the light moving away at c, and the photon will still "see" you moving away c (theoretically).

 ThreeRight wrote: its like, if your standing and your friend runs 4 mph away from you, and your friend looks back. Relative to your friend, it would look like you and the rest of the world is moving away from him at 4 mph.

i know this is what your common-sense tells you happens, but in reality, that is not what happens. It's just that for speeds like 4 mph, the difference between what really happens and what you think happens is pretty much impossible to notice.

Suppose you were standing still, and your friend was running toward you at 6 mph. i am also standing still, watching.
You see: him approaching you at 6 mph
He sees: you approaching him at 6 mph
i see: him approaching you at 6 mph

Now suppose you start running toward him at 6 mph.
You see: him approaching you at 12 mph
He sees: you approaching him at 12 mph
i see: you approaching him at 6 mph and him approaching you at 6 mph

So far everything should make sense. But that's only because the speeds are so small. Look at what happens when we change it from 6 mph to 0.6c.
You see: him approaching you at 0.88c (NOT 1.2c!)
He sees: you approaching him at 0.88c (NOT 1.2c!)
i see: you approaching him at 0.6c and him approaching you at 0.6c

Common sense works fine for common situations... low speeds. At high speeds, you can't use common sense.
EanofAthenasPrime
Okay, I have a question. My brain is kinda turned off right now, so I didn't try to actually compute this, but if there was railgun that shot a bullet that went 99.9999999999% c would it be relative similar to light? Like, for a spaceship going .5c that launched the rail gun, and from a stationary observer, would the bullet seem to be going at basically the same speed in both frames of refrence? Or do u have to go 100% c for this property to start?
Bikerman
 EanofAthenasPrime wrote: Okay, I have a question. My brain is kinda turned off right now, so I didn't try to actually compute this, but if there was railgun that shot a bullet that went 99.9999999999% c would it be relative similar to light?
Depends what you mean. It would be travelling nearly as fast as light but, unlike light, it has mass and would therefore show other effects when observed from another frame of reference. We will call the bullet's view of things BFOR (Bullet's frame of reference) and we will assume a stationary observer (SOFOR) and a Train travelling at 200km/h (TFOR). So those are the 3 reference points which make up our universe for this question.
 Quote: Like, for a spaceship going .5c that launched the rail gun, and from a stationary observer, would the bullet seem to be going at basically the same speed in both frames of reference? Or do u have to go 100% c for this property to start?
I see what you are asking. OK the answer is no. The bullet would appear to be travelling at different speeds (very marginally) when seen from TFOR and SOFOR,
The bullett could never actually reach c of course because it is massive (ie it possesses mass). Nothing with a positive mass at rest (intertial mass) can reach c. As the massive object gets closer to c, more and more of the energy from whatever force is being used to accelerate the object, gets converted into mass (m=e/c^2) and makes the object even more resistant to acceleration. According to the sums the bullet would have a mass of ∞ if it reached c.