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Speed of light Q.

post #1 of 17
Thread Starter 
I was watching a program about the Time travel.

Ok as i understood it, as you approach the speed of light (known as SoL from now on) time slows down, if you go faster than light, time goes backwards. These effects can be measured on earth, albeit very small, ie taking a plane trip across the atlantic, you will be travelling at speed, which means as far as you are concerned the trip took about 0.0001 seconds less than an observer from the stationary ground. A space shuttle trip may produce effects that are 1/4 of a second difference between observers.

My questions are.

1) The earth travells around the sun at very high speed. Therefore If I removed myself from the Earth to a completely stationary position in space and waited for the Earth to do one orbit of the sun, I should measure a greater duration than someone on earth. As the universe is rotating aswell, I wouldn't be completely still. But If I could maintain a position in space that cancelled out all the movements of everything, so that I was essentially not moving at all, would I measure time as infinitely fast?

2) If time slows as I approach the SoL and goes bacwards after I exceed it, I must therefore deduce that at exacly the SoL, there is no time measurement at all. Isn't it then true that lightbeams leaving a distant star say 1000 light years away (as we measure it on earth) actually reach a destination (as far as the beam is concerned) instantly, because at the SoL there is no measurement of time?

3) If this is true, what does it mean?
post #2 of 17
1) The earth travells around the sun at very high speed. Therefore If I removed myself from the Earth to a completely stationary position in space and waited for the Earth to do one orbit of the sun, I should measure a greater duration than someone on earth. As the universe is rotating aswell, I wouldn't be completely still. But If I could maintain a position in space that cancelled out all the movements of everything, so that I was essentially not moving at all, would I measure time as infinitely fast?

You are never not moving in this universe. The expansion of the universe would tug you in a direction much like the ocean forces a piece of driftwood to move despite no actions on the part of the wood. the differences in time measurements would be negligable.

2) If time slows as I approach the SoL and goes bacwards after I exceed it, I must therefore deduce that at exacly the SoL, there is no time measurement at all.

the sun is not massive enough to exibit this behaviour. You are describing what would happen if you approached a black hole. You see, light speed is a constant. If the sun was massive enough to stop time the point where time would stop, so would emmiting light. therefore light would stop and you wouldn't be able to see the sun because there is no light to shine on your retinas. It would be a black hole. On the grand scale of things the sun is just another unimpressive celestial object.

Isn't it then true that lightbeams leaving a distant star say 1000 light years away (as we measure it on earth) actually reach a destination (as far as the beam is concerned) instantly, because at the SoL there is no measurement of time?

No. Light is constant. The medium may affect the speed but in the vacuum of space light with travel at 300K kph. Photons do not have any sense of time so only the person making the measurement can determine the perceived time it takes for it to travel 1000 light years.
post #3 of 17
It's all relative. There is no "stopped" and "going". If two things are moving relative to one another that's all that counts. If the earth is "moving" and you are not then there will be a time shift.
post #4 of 17
[quote]Light is constant.<hr></blockquote>
Don't be so sure of that
<a href="http://www.sciencedaily.com/releases/1999/10/991005114024.htm" target="_blank">http://www.sciencedaily.com/releases/1999/10/991005114024.htm</a>
post #5 of 17
Thread Starter 
OUTSIDER.....

I think you completely misread my question. I stated that when i wrote SoL, I meant Speed of Light. It has nothing to do with our SUN, just a coincidence that the suns name is sol.

It always amazes me that when you ask a hypothetical question you'll always get a 'you cant do this because of stupid reason X.' even though the rest of the question is stupidly unobtainable. Its just a theory.

1) Im simply asking, if you could hold yourself completely still in space, cancelling out all movements of any kind, would Time flow infinitly fast?

2) Consider a spacecraft travelling at exactly the speed of light. (Forgetting all reasons why this is not possible yet). At this speed there is no time. Say you wanted to travel 100 light years in this craft to a distant planet, but as there is no time at the speed of light, how can you measure how long you need to be in transit for to reach the destination. You cannot say I need to travel for a hundred years, because on the craft you cannot measure a second, let alone a hundred years. Therefore as far as the craft is concerned you will reach your destination instantly and crash into it, or at least you will reach the mythical edge of the universe instantly as well.
post #6 of 17
[quote]Originally posted by MarcUK:
<strong>
1) Im simply asking, if you could hold yourself completely still in space, cancelling out all movements of any kind, would Time flow infinitly fast?</strong><hr></blockquote>

Still wrt what? What's moving and what's not? It's all relative to what two objects you want to compare. There is no absolute coordinate system.

[quote]Originally posted by MarcUK:
<strong>2) Consider a spacecraft travelling at exactly the speed of light. (Forgetting all reasons why this is not possible yet). At this speed there is no time.</strong><hr></blockquote>

No. It's all relative. For the person moving, time is moving along normally. For people not moving his time will be shifted.

The only difference is acceleration. Two people moving relative to one another at speed c. One will have to accelerate to match speed with the other. That's the key ... acceleration. To say that one of the two people is moving at c and the other isn't doesn't make sense and misses the point of relativity.

[quote]Originally posted by MarcUK:
<strong>Say you wanted to travel 100 light years in this craft to a distant planet, but as there is no time at the speed of light, how can you measure how long you need to be in transit for to reach the destination.</strong><hr></blockquote>

Going c it will take 100 years.

[quote]Originally posted by MarcUK:
<strong>You cannot say I need to travel for a hundred years, because on the craft you cannot measure a second, let alone a hundred years.</strong><hr></blockquote>

In your craft you measure a second to be a second, a year to be a year.

[quote]Originally posted by MarcUK:
<strong>Therefore as far as the craft is concerned you will reach your destination instantly and crash into it, or at least you will reach the mythical edge of the universe instantly as well.</strong><hr></blockquote>


Sigh
post #7 of 17
Thread Starter 
I've obviously got myself extremely confused at some point, sorry for wasting your time. I will do some investigations.

[ 05-11-2002: Message edited by: MarcUK ]</p>
post #8 of 17
There is a reason why mass can't go the speed of light. you just stumbled on it.
post #9 of 17
Thread Starter 
[quote]Originally posted by Outsider:
<strong>There is a reason why mass can't go the speed of light. you just stumbled on it.</strong><hr></blockquote>

Im not sure what you mean. What have I stumbled upon?

I've spent the last couple of hours GOOGLE-search Time-travel.

It states on several sites I visited that at the speed of light (C) that time stands still. But Scott_H is telling me that I will always observe my watch counting the seconds no matter what speed I travel. As I've earlier said, travelling at C should mean I can traverse any distance instantaniously, which again at least has been mentioned on several sites. This is because as you approach C, distance becomes shorter, until at C there is no distance.

Doesn't this then mean, going back to my original post, that as far as the light is concerned, travelling from a star 1000 light years away (as we measure it), it has actually reached us instantly?

Im not trying to start a fight here, Im just trying to understand!

[ 05-11-2002: Message edited by: MarcUK ]</p>
post #10 of 17
You can't go "c". You just can't. If I remember ... spin 1/2 particles cannot go faster than c but integer spin ones can. Photons are spin 1 they can go c. Protons electrons neutrons ups downs ... are half integer spin particles. They can't go faster than c and we are made of them.
post #11 of 17
Thread Starter 
[quote]Originally posted by scott_h_phd:
<strong>You can't go "c". You just can't. If I remember ... spin 1/2 particles cannot go faster than c but integer spin ones can. Photons are spin 1 they can go c. Protons electrons neutrons ups downs ... are half integer spin particles. They can't go faster than c and we are made of them.</strong><hr></blockquote>

Obviously, I don't understand what you write above. I understand that anything with mass cannot go 'C' because of the infinte amount of energy required for the acceleration, but Im not trying to disprove that. Im only trying to establish the theory that If I *could* travel at C, then time would stop and distance would be 0, thus making all travel of any distance to be instantanious. At the other end of the scale, if i *could* hold perfectly still, then time would be infinitely fast and distances would be infinitly large.

Can you Scott just tell me whether this theory is correct, rather than giving me a hundred reasons why I cant travel at C, or hold myself perfectly still?
post #12 of 17
Well If I could pass through matter and if I could teleport myself and if I could I find a infinite source of energy....

You may was well say "If the laws of physics did not apply what would physically happen".
post #13 of 17
Thread Starter 
7.1 Effects as One Approaches the Speed of Light

To begin, consider two observers, A and B. Let A be here on Earth and be considered at rest for now. B will be speeding past A at a highly relativistic speed as he (B) heads towards some distant star. If B's speed is 80% that of light with respect to A, then for him (as defined in Section 1.4 ) is 1.6666666... = 1/0.6. So from A's frame of reference, B's clock is running slow and B's lengths in the direction of motion are shorter by a factor of 0.6. If B were traveling at 0.9 c, then this factor becomes about 0.436; and at 0.99 c, it is about 0.14. As the speed gets closer and closer to the speed of light, A will see B's clock slow down infinitesimally slow, and A will see B's lengths in the direction of motion becoming infinitesimally small.
In addition, If B's speed is 0.8 c with respect to A, then A will see B's energy as a factor of larger than his rest-mass energy
where m(B) is the mass of observer B. At 0.9 c and 0.99 c this factor is about 2.3 and 7.1 respectively. As the speed gets closer and closer to the speed of light, A will see B's Energy become infinitely large.
Obviously, from A's point of view, B will not be able to reach the speed of light without stopping his own time, shrinking to nothingness in the direction of motion, and taking on an infinite amount of energy.
Now let's look at the situation from B's point of view, so we will now consider him to be at rest. First, notice that the sun, the other planets, the nearby stars, etc. are not moving very relativistically with respect to the Earth; so we will consider all of these to be in the same frame of reference. Remember that to A, B is traveling past the earth and toward some nearby star. However, in B's frame of reference, the earth, the sun, the other star, etc. are the ones traveling at highly relativistic velocities with respect to him. So to him the clocks on Earth are running slow, the energy of all those objects becomes greater, and the distances between the objects in the direction of motion become smaller.
Let's consider the distance between the Earth and the star to which B is traveling. From B's point of view, as the speed gets closer and closer to that of light, this distance becomes infinitesimally small. So from his point of view, he can get to the star in practically no time. (This explains how A seems to think that B's clock is practically stopped during the whole trip when the velocity is almost c. B notices nothing odd about his own clock, but in his frame the distance he travels is quite small.) If (in B's frame) that distance shrinks to zero as his speed with respect to A goes to the speed of light, and he is thus able to get there instantaneously, then from B's point of view, c is the fastest possible speed.
post #14 of 17
Thread Starter 
OK Scott I found this, which pretty much confirms what Ive been trying to establish.

But can I assume that because it is "B" who has undertaken the acceleration that it really is his time that has stopped? and not "A"'s who is relatively still.

Does this mean that from "B"'s point of view, when he reaches C, he will just be freeze framed? or does his watch still tick away the seconds, which I don't believe it could, as his time is now infinatley slow, ie stopped?
post #15 of 17
Well I'm not sure that I agree with everything that is above. Like I said above i had a chance to learn much more about this stuff but passed on it.

Everyone's own watch is always okay. We always think our time is the correct time and we don't know anything odd is happening. Because it's all relative.

Like I said the acceleration is the important part. If two people are traveling relative to one another, one thinks the other is the one moving, why would one clock be one way and the other the other way? If one "stops" and they compare clocks they will be off. Why should one clock be slower than the other? It's the acceleration.

It's messed up shit. I'll have to maybe go read up on it. But I'm not sure I care to spend the time. No pun
post #16 of 17
Thread Starter 
You'll be glad to know, Ive ordered a few books from Amazon, the famous Stevenhawkin book, and a couple of others about schrodingers Cats!
post #17 of 17
Time is a relative term, it's hard to really defined it.

As for question 1.

Why make you think for sure that you're moving at all?

Why make you think for sure that the earth revolves around the sun and not the other way around, or even the whole universe revolves around the earth?

For all we know that, we could be the center of the universe and everything revolves. Or perharps that we already exist in many points in the universe, or... we didn't even exist in this universe and we only thought that we exist in the universe. So... Perharps we can change our present location easily, much like on how a 3D modeler change the location of his 3D model in 3D space. Insert coordinate and you're there. Of course the 3D modeler can animate his 3D model so that it will always in different location at each particular timelie so that there's a perceive illusion of motion, but it's only an illusion.

Moving in time, moving in space, it's all merely an illusion.

Okay. That would be the philosophical pondering for the day. Yes, it can be confusing.

As for the question. I wouldn't know for sure. No one ever tried going at a absolute static point in the universe and see the whole universe there.

As for question 2.

I wouldn't know for sure. No one ever tried going at the speed of light, travel a few light years away, and checked if they're experiencing the whole ride in a few years or just a few seconds (or less or even instantanious).

I do understand your confusion over this kind of stuff. For years, we the public are always told by the scientific documentaries and communities that explained on how when something move closer to the speed of light, it will aged slower. And how stars are light years aways.

But we are sometimes never told that, is the light years the distance or how long it take to go there (perceived by the person that is traveling near or at the speed of light)? Astronomers always saying, that this star is 15 light years away, but 15 years to whom? To us or the light?
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