126 replies to this topic

[Pliny]

Already answered.

But....but.... but...how do I see a shift if light is traveling at the same speed relative to myself from all sources. Sound is traveling through a medium - air, and the medium is what causes the frequency shift as the source moves away. Now you said that, "if I am approaching a source of light, each pulse of light has less distance to cover before it reaches me. So you observe them to reach you more frequently than they are emitted. Converse true for if you are moving away from the source." That does not jibe with special relativity. Light from all sources travels, relative to me, at the same speed, there can be no more "frequently emitted pulses of light" I could observe from anywhere.

[ToadBrother]

That being true then, and you appreciatively put it in better words than I, how is a perception of red shift and blue shift possible?

For goodness sakes, Pliny, the Doppler Effect has to do with how waves reach an observer. I don't know how you're confused about this as a number of people here have explained over and over and over again.

[ToadBrother]

But....but.... but...how do I see a shift if light is traveling at the same speed relative to myself from all sources. Sound is traveling through a medium - air, and the medium is what causes the frequency shift as the source moves away. Now you said that, "if I am approaching a source of light, each pulse of light has less distance to cover before it reaches me. So you observe them to reach you more frequently than they are emitted. Converse true for if you are moving away from the source." That does not jibe with special relativity. Light from all sources travels, relative to me, at the same speed, there can be no more "frequently emitted pulses of light" I could observe from anywhere.

The speed of light is not infinite. That's what you seem to be suggesting, because that's the only way what you're saying makes any sense. Since the speed of light is finite, it takes time for a photon to cover a particular distance.

[Pliny]

Pliny, the energy involved in applying a force is given by the following equation:

Energy = force * distance

If the object that the force is being applied to doesn't move any distance, no energy is spent. This is basic grade 8 physics here. The magnet is sitting still, not moving. Therefore no energy is expended.

So if I push against a wall and neither the wall nor I move any distance then no energy has been expended, although I might break out into a sweat.

That's a mathematical formula for determining the amount of energy expended to move an object a specified distance. If the distance is zero of course mathematically I get an answer of zero. I may apply a force but not enough to overcome the inertia of the mass. Does that mean zero energy has been expended?

But in fact, a magnet on a fridge does not drop to the floor. The force of gravity, is pulling it's mass toward the floor. The properties of the magnet are keeping it stationary resisting the pull of gravity. In effect, it is similar to me holding a ball outward in my hand, I am expending energy by preventing the ball from dropping. When I run out of energy and can no longer hold the ball it drops to the ground.

Essentially, a state of equilibrium of forces is attempted to be achieved by all objects, it takes energy to maintain them in a state out of equilibrium. All objects on Earth to reach equilibrium remain on the ground. An energy is applied to move it off the ground and it must be continuously applied to keep it off the ground in a state out of equilibrium. The magnet behaves as any other object that is put on a vertical surface. It falls off, unless it is in contact with a ferrous metal, in which case it does not.

The formula tells me no energy is being expended. The magnet is moving 0 distance. Is this the case?

If I have two magnets and hold them apart, keeping their polar opposites from moving toward each other. I must use force. How long I can apply the force to keep them apart is the amount of energy I have to keep them apart. I don't see how that energy can be zero???

Edited by Pliny, 27 October 2011 - 12:19 AM.

[Pliny]

The speed of light is not infinite. That's what you seem to be suggesting, because that's the only way what you're saying makes any sense. Since the speed of light is finite, it takes time for a photon to cover a particular distance.

If an observer were traveling at light speed would light appear to be traveling at light speed relative to that observer or would it appear stopped. Doesn't special relativity essentially imply that the speed of light is infinite since it's speed is constant relative to all observers - or do you exclude an observer traveling at light speed or one at half the speed of light.

[Pliny]

For goodness sakes, Pliny, the Doppler Effect has to do with how waves reach an observer. I don't know how you're confused about this as a number of people here have explained over and over and over again.

I am not confused by the Doppler effect. I am confused as to how it applies to light as regards special relativity.

The Doppler effect is created by a moving source where the signal is compressed in the direction of a moving source and thus the frequency sounds higher as it approaches and gets lower as it moves away.
It is the compression of the sound by the motion of the source as it moves toward an observer that makes it's frequency seem higher. The sound being emitted by the source is catching up to the sound already emitted, so to speak.

If the source is not moving all listeners will hear the same frequency.

In special relativity, light is moving at the same speed relative to all observers. The light from the source is then traveling away at the same speed in all directions. There is no compression of light in the direction of the source as it moves. It moves the same speed away in all directions as though the source is motionless. That is the claim of special relativity. The source being motionless means there can be no Doppler Effect, that is to say, shift in frequency to observers from a motionless source.

Intuitively, we think the star is moving away from us thus the Doppler Effect seems a plausible concept that can be applied to light frequency. The light emitted as the source moves towards a direction is catching up to the light already emitted, in the same manner as sound. Thus a frequency shift should be observable. Why everyone has been trying to tell me that over and over escapes me. But if light travels the same speed relative to all observers as special relativity states, it violates the theory of special relativity to say a frequency shift can be observable.

Edited by Pliny, 27 October 2011 - 12:23 AM.

[Wild Bill]

If an observer were traveling at light speed would light appear to be traveling at light speed relative to that observer or would it appear stopped. Doesn't special relativity essentially imply that the speed of light is infinite since it's speed is constant relative to all observers - or do you exclude an observer traveling at light speed or one at half the speed of light.

First of all, unless someone invents a Star Trek space warp drive it is impossible to travel at light speed. Einstein's simple equation of E=MxC^2 means that Energy equals Mass times the Speed of Light Squared! If you understand this and dig a bit deeper you realize that this means that the faster you go the more your Mass increases, which means you need more energy to accelerate even faster. You may start at 100 lbs of Mass but at 20% of light speed you may have 130 lbs. The rate of increase is also not linear but follows a curve. When you get close to the speed of light your apparent Mass becomes so great that there is no longer enough energy in the Universe to make you go any faster!

But for purposes of argument let's assume that your model is real. If an observer were traveling at light speed and measured the speed of light he would get the exact same value of any other observer traveling at any different speed. This has been stated over and over in this thread but you either just can't or won't accept it or you are just trolling us!

If you think about this long enough you will come to understand that there is only one way such a thing could be true. The observer's time rate must be FAR slower than ours! To him, everything is perfectly normal but to US he is moving so slow as to look like a fly in amber. The speed of light hasn't changed! It is still exactly the same value as measured by any other observer traveling at any other speed! The CLOCKS move faster or slower! The rate of time passing is different for each observer but there's no way for any observer to be able to know that. To him, it takes the same time to boil water for a cup of tea as anybody else, anywhere.

I can't comment on your suggestion stating that the speed of light is infinite 'cuz I have absolutely no idea of where that came from or how it is relevant!

No one, including Einstein, has ever said that the speed of light is infinite!

You're breaking new territory here, Pliny. You should marry Betsy.

Edited by Wild Bill, 27 October 2011 - 07:39 AM.

[Pliny]

First of all, unless someone invents a Star Trek space warp drive it is impossible to travel at light speed. Einstein's simple equation of E=MxC^2 means that Energy equals Mass times the Speed of Light Squared! If you understand this and dig a bit deeper you realize that this means that the faster you go the more your Mass increases, which means you need more energy to accelerate even faster. You may start at 100 lbs of Mass but at 20% of light speed you may have 130 lbs. The rate of increase is also not linear but follows a curve. When you get close to the speed of light your apparent Mass becomes so great that there is no longer enough energy in the Universe to make you go any faster!

But for purposes of argument let's assume that your model is real. If an observer were traveling at light speed and measured the speed of light he would get the exact same value of any other observer traveling at any different speed. This has been stated over and over in this thread but you either just can't or won't accept it or you are just trolling us!


If you think about this long enough you will come to understand that there is only one way such a thing could be true. The observer's time rate must be FAR slower than ours! To him, everything is perfectly normal but to US he is moving so slow as to look like a fly in amber. The speed of light hasn't changed! It is still exactly the same value as measured by any other observer traveling at any other speed! The CLOCKS move faster or slower! The rate of time passing is different for each observer but there's no way for any observer to be able to know that. To him, it takes the same time to boil water for a cup of tea as anybody else, anywhere.

I can't comment on your suggestion stating that the speed of light is infinite 'cuz I have absolutely no idea of where that came from or how it is relevant!

No one, including Einstein, has ever said that the speed of light is infinite!

You're breaking new territory here, Pliny. You should marry Betsy.

Hey Wild Bill! That's funny.

Special relativity theorizes that "light travels at a constant velocity relative to all observers". I didn't have an argument from anyone about that.

So what does it mean when special relativity states that "light moves at a constant velocity relative to all observers"? It is not qualified by the statement "unless the observers are moving; in which case it's velocity would be calculated as being plus or minus the relative velocity of the observers" - even though you would intuitively think that. So adding that qualifier invalidates the statement special relativity makes that light moves at a constant velocity relative to all observers. Isn't that saying that the velocity of an observer relative to light must be zero, and the velocity of all observers relative to light must be zero?

But for purposes of argument let's assume that your model is real. If an observer were traveling at light speed and measured the speed of light he would get the exact same value of any other observer traveling at any different speed. This has been stated over and over in this thread but you either just can't or won't accept it or you are just trolling us!

That makes sense but we are talking about relativity theory here. Observers would have to be measuring light realtive to other things and the statment is that "light travels at constant speed relative to all observers" not relative to other things.

Edited by Pliny, 27 October 2011 - 09:15 AM.

[Wild Bill]

Hey Wild Bill! That's funny.

Special relativity theorizes that "light travels at a constant velocity relative to all observers". I didn't have an argument from anyone about that.

So what does it mean when special relativity states that "light moves at a constant velocity relative to all observers"? It is not qualified by the statement "unless the observers are moving; in which case it's velocity would be calculated as being plus or minus the relative velocity of the observers" - even though you would intuitively think that. So adding that qualifier invalidates the statement special relativity makes that light moves at a constant velocity relative to all observers. Isn't that saying that the velocity of an observer relative to light must be zero, and the velocity of all observers relative to light must be zero?



That makes sense but we are talking about relativity theory here. Observers would have to be measuring light realtive to other things and the statment is that "light travels at constant speed relative to all observers" not relative to other things.

I'm sorry Pliny but I just give up! I'm not sure if you're just yanking our chains or that in real life you write science articles for WatchTower magazine!

Life's too short!

[kimmy]

So if I push against a wall and neither the wall nor I move any distance then no energy has been expended, although I might break out into a sweat.

That's a mathematical formula for determining the amount of energy expended to move an object a specified distance. If the distance is zero of course mathematically I get an answer of zero. I may apply a force but not enough to overcome the inertia of the mass. Does that mean zero energy has been expended?

If you lean a stick against a wall, the stick is applying force to the wall. Possibly for hours, days, or even many many years. Does that mean the stick is generating infinite energy?

No, Pliny, it does not. And as usual the problem here is that you just don't understand what you're talking about.

You're expending energy by pressing against the wall-- contracting your muscles uses chemical energy, and generates heat. But you're not generating energy any more than the stick leaning against the wall is generating energy.

But in fact, a magnet on a fridge does not drop to the floor. The force of gravity, is pulling it's mass toward the floor. The properties of the magnet are keeping it stationary resisting the pull of gravity. In effect, it is similar to me holding a ball outward in my hand, I am expending energy by preventing the ball from dropping. When I run out of energy and can no longer hold the ball it drops to the ground.

And holding the ball at constant height is no different from a table holding a ball at constant height. Is the table burning energy? If a ball sits on a table for 100 years, does that mean that the table has generated an incalculable amount of energy during that time? No.

Essentially, a state of equilibrium of forces is attempted to be achieved by all objects, it takes energy to maintain them in a state out of equilibrium.

Nope.

All objects on Earth to reach equilibrium remain on the ground. An energy is applied to move it off the ground

yep

and it must be continuously applied to keep it off the ground in a state out of equilibrium.

nope

The magnet behaves as any other object that is put on a vertical surface. It falls off, unless it is in contact with a ferrous metal, in which case it does not.

The formula tells me no energy is being expended. The magnet is moving 0 distance. Is this the case?

yep

If I have two magnets and hold them apart, keeping their polar opposites from moving toward each other. I must use force. How long I can apply the force to keep them apart is the amount of energy I have to keep them apart. I don't see how that energy can be zero???

If you put a brick between two magnets to keep them apart, is the brick generating energy? Nope.

Your muscles are burning chemical energy while you're holding the magnets in place, but that energy isn't being added to the system of magnets. It's being lost as heat. It's not being added to the system of the magnets.


-k

Edited by kimmy, 27 October 2011 - 11:12 PM.

[kimmy]

So what does it mean when special relativity states that "light moves at a constant velocity relative to all observers"? It is not qualified by the statement "unless the observers are moving; in which case it's velocity would be calculated as being plus or minus the relative velocity of the observers" - even though you would intuitively think that. So adding that qualifier invalidates the statement special relativity makes that light moves at a constant velocity relative to all observers. Isn't that saying that the velocity of an observer relative to light must be zero, and the velocity of all observers relative to light must be zero?

No, Pliny...


If I'm driving my spaceship at a speed of c/2 and there is an observer directly in front of me... the light from my headlights is approaching him at c and I am approaching him at c/2. From my point of view, the light from my headlights is also moving at the speed of light, and the observer is coming towards me at .5c.

You might intuitively think "she's moving at .5c and from her point of view light is moving at c so from the point of view of somebody watching, the net effect should be .5c + c = 1.5c". But you'd be mistaken, because you'd be mixing information from 2 different frames of reference.



-k

[Bonam]

Dunno how you had the patience for that kimmy, I just gave up a few posts ago

[GostHacked]

Hey Wild Bill! That's funny.

Special relativity theorizes that "light travels at a constant velocity relative to all observers". I didn't have an argument from anyone about that.

So what does it mean when special relativity states that "light moves at a constant velocity relative to all observers"? It is not qualified by the statement "unless the observers are moving; in which case it's velocity would be calculated as being plus or minus the relative velocity of the observers" - even though you would intuitively think that. So adding that qualifier invalidates the statement special relativity makes that light moves at a constant velocity relative to all observers. Isn't that saying that the velocity of an observer relative to light must be zero, and the velocity of all observers relative to light must be zero?

That makes sense but we are talking about relativity theory here. Observers would have to be measuring light realtive to other things and the statment is that "light travels at constant speed relative to all observers" not relative to other things.

Light travels at about 300,000 KMS per second. The speed at which we travel is practically negligible, so this is why light travels the same speed for all observers. We are moving much much much slower.

[kimmy]

Dunno how you had the patience for that kimmy, I just gave up a few posts ago

As Bill suggested, it's almost turning into a Betsy situation, where people stop replying and one party thinks "a ha! I'm asking questions they can't answer!" when the truth is that everybody else has decided he's beyond hope. This is becoming as frustrating as teaching my cat to type, but I hate giving up because I hate leaving him with the impression that he's debunked all of modern physics by asking really dumb questions.

Light travels at about 300,000 KMS per second. The speed at which we travel is practically negligible, so this is why light travels the same speed for all observers. We are moving much much much slower.

No, Gost, that's not correct. See my previous post.

-k

[Pliny]

No, Pliny...


If I'm driving my spaceship at a speed of c/2 and there is an observer directly in front of me... the light from my headlights is approaching him at c and I am approaching him at c/2. From my point of view, the light from my headlights is also moving at the speed of light, and the observer is coming towards me at .5c.

Does "from your point of view" mean the same as "relative to you"? If so then I exactly agree.

I am saying, "relative" to you in your speeding spaceship, light is traveling at the speed of light. And "relative" to the observer in front of you light is traveling at the speed of light.

The measurement of the speed of light is made "relative to each of the observers" not from one of the observers.

You might intuitively think "she's moving at .5c and from her point of view light is moving at c so from the point of view of somebody watching, the net effect should be .5c + c = 1.5c". But you'd be mistaken, because you'd be mixing information from 2 different frames of reference.
-k

Exactly.

So now how is what you just said different from what I have been saying? That should be easy to figure out.