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raed

Posted: Fri Jun 13, 2008 7:45 pm Post subject: Relavtivity

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If a train" X" is moving at 400 km/hour in relation to the earth ,Inside the train there is a similar object "Y" moving with 400 km/hour.
So the object "Y" is moving at 800 km/hour in relation to the earth , if we repeat this system for several times , Could we get the speed of light ??

I mean , It's not feasible , but can any one say it's impossible ??!
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SuperNatendo

Posted: Fri Jun 13, 2008 8:17 pm Post subject: Re: Relavtivity

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raed wrote:

speed of light measured from train going 400 km/hour = 299 792 458 m / s

speed of light measured from train going 400 km/hour inside another train going 400 km/houre = 299 792 458 m / s

in other words, yes, we can say it, it is impossible.

now, as for actually warping space-time in the vicinity of the train to give the illusion that you somehow traveled faster than the speed of light, yes, that is possible.
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mitchellmckain

Posted: Sat Jun 14, 2008 1:03 am Post subject: Re: Relavtivity

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raed wrote:

Relativity modifies the calculation you are makin with the following formula

v = (v1 + v2)/(1+ v1 v2 / c^2)

so for example your trains gives

(400 km/hour + 400 km/hour)/(1+ (400km/hr)^2/(1079252850km/hr)^2)

Since 1,079,252,850 km/hr is the speed of light in km/hr

To the precision of a typical calculator this will just give 800km/hr

But if your trains are going 400,000,000 km/hr the result will NOT be 800,000,000 km/hour

(400,000,000 km/hour + 400,000,000 km/hour)/(1+ (400,000,000km/hr)^2/(1079252850km/hr)^2) is equal to 703,380,674 km/hr

With this formula any two velocities will add up to less than the speed of light.
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SuperNatendo

Posted: Sat Jun 14, 2008 8:40 am Post subject:

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mitchellmckain wrote:

v = (v1 + v2)/(1+ v1 v2 / c^2)

so for example your trains gives

(400 km/hour + 400 km/hour)/(1+ (400km/hr)^2/(1079252850km/hr)^2)

Since 1,079,252,850 km/hr is the speed of light in km/hr

To the precision of a typical calculator this will just give 800km/hr

But if your trains are going 400,000,000 km/hr the result will NOT be 800,000,000 km/hour

(400,000,000 km/hour + 400,000,000 km/hour)/(1+ (400,000,000km/hr)^2/(1079252850km/hr)^2) is equal to 703,380,674 km/hr

With this formula any two velocities will add up to less than the speed of light.

I thought the equation was:

V = (V1 + V2)/1 + ((V1 + V2)/(C^2))

So shouldn't that be (400 km/hr + 400 km/hr)/(1 + (400 km/hr + 400 km/hr) / (1079252850km/hr^2))

?

Also Mitchell, I'm running into a paradox here.

Lets Say I'm trying to get to Barnard's Star, that is 6.0 light years away. I leave earth at what earth sees as 0.99% the speed of light. Now, at this speed, earth sees me shortened lengthwise at about 7 times, and my clocks moving about 7 times slower. To them, when I stop at Barnard's Star, a little more than 6 yrs have passed, but they know that on the ship, the clocks and my aging are just about 11 months older than when I left earth.

Now, From my perspective, time is going by as normal, but everything outside my ship appears to be shortened lengthwise at about 7 times, and the orbit of the earth around the sun is going 7 times slower. The shorter distances allowed me to get to Barnard's Star at about a years worth of time. As I watched the earth orbit the sun during my trip, the earth appeared to be taking 7 times as long to orbit as it used to. By the time I reach Barnard's Star, It appears that the earth has only advanced about 11 months. However, knowing that the light is taking 6 yrs to get to me, I know the clocks on earth say it has been 6 yrs and 11 month since I left even though it seemed like it only took me 11 months to get there.

When I turn around and head back to earth, I watch as my home planet seems to rotate the sun the equivalence of 22 months over the combined time of my trip, yet the people on earth are supposedly 13 yrs and 10 months older?

How does this make any sense whatsoever?
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Janus

Posted: Sat Jun 14, 2008 12:13 pm Post subject:

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SuperNatendo wrote:

I thought the equation was:

V = (V1 + V2)/1 + ((V1 + V2)/(C^2))

So shouldn't that be (400 km/hr + 400 km/hr)/(1 + (400 km/hr + 400 km/hr) / (1079252850km/hr^2))

?

I don't know where you got that equation from, but it is not the correct one for velocity addition

Quote:

Also Mitchell, I'm running into a paradox here.

Lets Say I'm trying to get to Barnard's Star, that is 6.0 light years away. I leave earth at what earth sees as 0.99% the speed of light. Now, at this speed, earth sees me shortened lengthwise at about 7 times, and my clocks moving about 7 times slower. To them, when I stop at Barnard's Star, a little more than 6 yrs have passed, but they know that on the ship, the clocks and my aging are just about 11 months older than when I left earth.

Now, From my perspective, time is going by as normal, but everything outside my ship appears to be shortened lengthwise at about 7 times, and the orbit of the earth around the sun is going 7 times slower. The shorter distances allowed me to get to Barnard's Star at about a years worth of time. As I watched the earth orbit the sun during my trip, the earth appeared to be taking 7 times as long to orbit as it used to. By the time I reach Barnard's Star, It appears that the earth has only advanced about 11 months. However, knowing that the light is taking 6 yrs to get to me, I know the clocks on earth say it has been 6 yrs and 11 month since I left even though it seemed like it only took me 11 months to get there.

When I turn around and head back to earth, I watch as my home planet seems to rotate the sun the equivalence of 22 months over the combined time of my trip, yet the people on earth are supposedly 13 yrs and 10 months older?

How does this make any sense whatsoever?

There seems to be quite a bit of confusion in your post. A lot of it stems form confusing what you see happening on Earth and what you determine is happening on Earth.

To find what you determine what is happening on Earth according to you, you use the Time dilation formula:

T = T`/sqrt(1-vÂ²/cÂ²).

To find what you see happening on Earth you use the Relativistic Doppler effect formula:

f = f`* sqrt((1-v/c)/(1+v/c))

One thing to note is that v is positive for velocities of objects moving away from each other and negative for objects approaching each other.

For the Time dilation formula, this doesn't make any difference because v is squared, but for the Doppler shift formula it does matter.

Taking your problem for example:(

Using time dilation, you would determine that the Earth aged at 1/7 the rate you do on the outgoing trip. Thus if you aged 10.26 mo., the Earth will have aged 10.26/7 = 1.47 mo (Not 6 yr/7 = 11 mo.)
This is how much the Earth has aged according to you.

Using Dopper shift, you would see the Earth age at 1/14 the rate you do. Thus you will see the Earth age 10.26/14 = .7328 mo.

On the return trip, you will determine by time dilation that the Earth will again age 11/7 = 1.57 mo. (Yes, I know, 1.57 + 1.57 mo = 3.14 mo., and the Earth's total accumulated during the trip should be 12.12 yrs, but we'll come back to that later on.)
Using Doppler shift you will see the Earth age at a rate of:

sqrt((1-(-.99c)/c)/(1+(-.99c/c)) = 14 times you do. This is 10.26*14 = 154 mo. = 11.97 yrs.

Add this to the .7328 mo aged during the outbound trip and you get 12.03 yrs. (the difference between this and the 12.12 you should get is due to accumulated rounding error.

Thus while you age 1 year 8.5 mo., you see the Earth age 12 yrs 1.5 mo. during the trip. No paradox.

Now, back to that 11+ year difference between what the you have determined by time dilation that Earth has aged and what it has actually.

The problem is in what happens during the period when you slow down and turn around to return to Earth. During this period, you are no longer in a single inertial frame, And thus the standard time dilation formula and rules can not be applied. Instead, you must use the rules for an accelerated frame. And to cut to the chase, these rules will have you determining that during this period of acceleration on your part, the earth will have aged some 11 yrs 10+ mo.

So, to recap: Doppler shift gives you what you will see.

Time dialation gives you what you will determine. (after all light signal delay times have been accounted for.)
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William McCormick

Posted: Sun Jun 15, 2008 10:44 am Post subject: Re: Relavtivity

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SuperNatendo wrote:

raed wrote:

You cannot warp space. Space is just a place for matter. It has no charge, and there is nothing to effect.

You can create electrical fields that will move matter, change its structure/shape, or change its density, matter that is in space.

But I see no effect on space that would even fall into the realm of science.

Sincerely,

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425 Chaotic Requisition

Posted: Sun Jun 15, 2008 12:08 pm Post subject:

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To say your all 'qualified' it doesn't give me much faith seeing that you all disagree with each other about the equations. Plus. McCormick, what the heck are you talking about?

Quote:

You cannot warp space. Space is just a place for matter. It has no charge, and there is nothing to effect.

Space is spacetime and thus warps due to mass, thats plainly obviously been proven many years ago with the eclipse as the first. Why would space have charge and by nothing to effect what are you reffering to? We all know there is such a thing as permeability of space, varying constants in different types of space. Don't we live in Minkowski space at the moment?

Quote:

You can create electrical fields that will move matter, change its structure/shape, or change its density, matter that is in space.

Yes, spacetime can do that as well, aka gravity being curved spacetime whats your point?

Quote:

But I see no effect on space that would even fall into the realm of science.

Space is everything along side time as the same entity, space is everything with time. How can space not fall into the realm of science, space-time after all is the base of all science.

To answer your question as simply and innocently as possible:

Every new addition of speed will be percieved in numerous ways, so theoretically each observor at every 400 kph would take more or less time to see that one object at 1c. There would be many different observation points to observe with many different time differentials and thus a different time dilation near light speed occuring for each unique observor. So yes we could reach the speed of light, but I'm not sure if that which is seen to be travelling at 1c will be seen by everyone to be travelling at 1c, that especially includes the last 400kph.

But why not, yes.
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mitchellmckain

Posted: Sun Jun 15, 2008 12:51 pm Post subject:

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SuperNatendo wrote:

I thought the equation was:

V = (V1 + V2)/1 + ((V1 + V2)/(C^2))

So shouldn't that be (400 km/hr + 400 km/hr)/(1 + (400 km/hr + 400 km/hr) / (1079252850km/hr^2))

Try a google of >relativity velocity addition< if you don't believe me.

SuperNatendo wrote:

Correct... well it is not actually seeing... it is acutally what they calculate must be the case when they take into account that the light they see you by is traveling at 1079252850km/hr.

SuperNatendo wrote:

To them, when I stop at Barnard's Star, a little more than 6 yrs have passed, but they know that on the ship, the clocks and my aging are just about 11 months older than when I left earth.

.8658 years or 10 months and 12 days older, yes.

SuperNatendo wrote:

Now, From my perspective, time is going by as normal, but everything outside my ship appears to be shortened lengthwise at about 7 times, and the orbit of the earth around the sun is going 7 times slower. The shorter distances allowed me to get to Barnard's Star at about a years worth of time. As I watched the earth orbit the sun during my trip, the earth appeared to be taking 7 times as long to orbit as it used to. By the time I reach Barnard's Star, It appears that the earth has only advanced about 11 months.

Correct. HOWEVER, this all changes when you start slowing down in order to stop at Barnard's Star or turn around to go back. While you are slowing down you would "see" (or calculate) that the earth is going around the sun extra fast in order to catch up so that by the time you stop at Barnard's Star you find that the people on earth are completely correct and that over 6 years passed on the earth while only 10.4 months passed for you.

SuperNatendo wrote:

When I turn around and head back to earth, I watch as my home planet seems to rotate the sun the equivalence of 22 months over the combined time of my trip, yet the people on earth are supposedly 13 yrs and 10 months older?

How does this make any sense whatsoever?

Accelerating back to 99% of the speed of light again you would calculate that the clocks on earth are going 7 times slower than your own, BUT while you were accelerating you calculate that the earth went around the sun, equivalent to the passage of 5.2 years so that when you get there 10.4 months later a total of 6.06 years will have passed on earth during your return trip.

In order to really understand relativity you MUST understand the relativity of simultaneity. That is the key to EVERYTHING.

425 Chaotic Requisition wrote:

To say your all 'qualified' it doesn't give me much faith seeing that you all disagree with each other about the equations. Plus. McCormick, what the heck are you talking about?

Nobody who is qualified is disagreeing about equations. (Hint: SuperNatendo, while intellegent and well spoken, has presented no reason for us to consider him "qualified"). And I don't think either I or Janus is going to be able to help you with McCormick. I don't even try to understand him.

425 Chaotic Requisition wrote:

Quote:

You cannot warp space. Space is just a place for matter. It has no charge, and there is nothing to effect.

In addition, if you don't call, the length contraction that squashes 6 light years down to only .857 light years in the direction you are moving when you travel at 99% of the speed of light, warping space, then I REALLY don't know WHAT warping space could mean otherwise!
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Last edited by mitchellmckain on Mon Jun 16, 2008 6:46 am; edited 2 times in total

Cold Fusion

Posted: Sun Jun 15, 2008 1:33 pm Post subject:

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Quote:

On the other hand, the observer on the platform sees the back of the train moving toward the point at which the flash was given off, and the front of the train moving away from it. This means that the light flash going toward the back of the train will have less distance to cover than the light flash going to the front.

http://en.wikipedia.org/wiki/Relativity_of_simultaneity

But then wouldn't this mean that if you were the back wall of the train, you would see light moving faster at you than it normally would? Isn't this impossible, to see light moving faster than c?

Why would earth appear to move slower while traveling away form it? I thought that through time dilation everything would appear to move faster. What about an object perpendicular to you while traveling at high speeds away from earth? Would this objects time rate appear to go by slower?
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Janus

Posted: Sun Jun 15, 2008 2:01 pm Post subject:

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Cold Fusion wrote:

Quote:

No, that's the whole point. Everyone measures light as moving at c with respect to themselves. Thus any observer anywhere on the train would "see" that the flash starts at the center of the Train, travels at c with respect to the train and strikes the back of the train and the front of the train simultaneously. Conversely, any observer anywhere on the platform or embankment will "see" the flash start at the middle of the train, travel at c with respect to the platform and hit the back of the train before the front of the train. Ergo, relativity of Simultaneity; Events that are simultaneous for observers on the train, are not simultaneous for observers on the embankment.

Quote:

Why would earth appear to move slower while traveling away form it? I thought that through time dilation everything would appear to move faster.

Two reasons:
1. Doppler shift
2. Time dilation. There is no absolute frame of rest in Relativity, Thus every observer is "at rest" as far as he is concerned. To an observer in the ship, it is the Earth that is moving away from him, and the Earth that undergoes time dilation.
A good rule of thumb in SR:
Time dilation always happens to the "other guy".

Quote:

What about an object perpendicular to you while traveling at high speeds away from earth? Would this objects time rate appear to go by slower?

If the object has a velocity with respect to you, yes.
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Cold Fusion

Posted: Sun Jun 15, 2008 2:57 pm Post subject:

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So then the light traveling towards the front of the train appears, or does go slower than it should be going through adding c to the velocity of the train? Essentially then light cannot go c+v1, so it eliminates the v1 by moving v1 slower and therefore ends up at c again....causing it to appear to get to the right forward side slower.
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Janus

Posted: Sun Jun 15, 2008 5:33 pm Post subject:

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Cold Fusion wrote:

OR, you can simply conclude that the speed of light is independent of its source.
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William McCormick

Posted: Sun Jun 15, 2008 6:10 pm Post subject:

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425 Chaotic Requisition wrote:

To say your all 'qualified' it doesn't give me much faith seeing that you all disagree with each other about the equations. Plus. McCormick, what the heck are you talking about?

Quote:

You cannot warp space. Space is just a place for matter. It has no charge, and there is nothing to effect.

Quote:

You can create electrical fields that will move matter, change its structure/shape, or change its density, matter that is in space.

Yes, spacetime can do that as well, aka gravity being curved spacetime whats your point?

Quote:

But I see no effect on space that would even fall into the realm of science.

Space does not change. It is emptiness. It is filled with matter and free electrons. Matter can be effected. However you cannot effect space.

You can bend, twist, crush, disassemble/explode, shrink, and expand matter, however the space remains the same.
Doing those things to matter may cause light or other rays to act strangely. Somehow scientists started to associate the light gases of space with space itself. They are totally two different things. Just more poor science.

There is just nothing in pure space. Space is a three dimensional area. You cannot effect it. You can fill it, you can nearly empty it. But that is about it.

I would have to listen to an argument that the matter creates the space. Only because I cannot leave the Universe to find out. However I do not believe so. I highly suspect that space is self supporting.

Gravity does not cause light to bend. The structure, different density gases, around the sun created by gravity causes the light to bend. Two very different things. One very poor science the other reproducible without a planets gravity field.

Sincerely,

William McCormick
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serpicojr

Posted: Sun Jun 15, 2008 6:23 pm Post subject:

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William McCormick wrote:

Space does not change... However you cannot effect space.

How do you know? Where's your proof?

SuperNatendo

Posted: Sun Jun 15, 2008 8:29 pm Post subject:

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OK, I don't think I understand the relativity of simultaneity as explained by the lightning thing. The person on the train who sees the lightning, sees the light traveling from the front of the train and from the back of the train at the same speed, however, since he is moving towards the front lightning strike, the light from the front strike hits his mirror first, while the second strike appears to happen afterwards. This is because from his frame of reference, the two events are not occurring at the same time, the simultaneous event only happens in the frame of reference of the observer on the ground.

I just don't understand this occurrence, I mean, if this is true, someone observing the big bang from a different frame of reference might actually see everything happening simultaneously, while we, being in a different frame of reference, think it all happened in succession.

I really wish I could grasp this better. It just makes me appreciate Einstein for figuring this out, if it were me I would have thought something was a little bit off in my brain!

Also, I heard the example of the train and the tunnel. The train, from the frame of reference of someone on the ground, appears to be really short. There is a tunnel up ahead, that due to the shortness of the train, appears as though you can close both ends of the tunnel and trap the train, yet according to people on the train, the outside world is very short and there is no way the train could fit its front and back in the tunnel at the same time.

All of this also ties mass in with your speed, which is why a particle that travels at the speed of light would have infinite mass, unless its rest mass began at 0.

Crazy stuff, but I won't give up until I understand it.

P.S. Yeah, I was wrong about my equation, You both had it right, I am new at the math behind the theory, I am just an amateur "scientist", just very interested in the rules of the universe is all, Trying to learn as much as I can.
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