The "at rest" portion of the thought experiment does not correspond to any known property of a photon.

BUT - I strongly suggest you get up to date on photon mass expression as demonstrated in experiments.

 

BUT - I strongly suggest you get up to date on photon mass expression as demonstrated in experiments

Sure, got a link?

 

Just to play devils advocate for a bit, many people 100 years ago were all making some VERY convincing arguments that it was impossible to move faster than the speed of sound. They knew that as you approached it, a shock-wave built up, and they proposed that you couldn't pass through that.
Since we've never actually accelerated anything with any sensors onboard nearly fast enough for it to start encountering substantial relativistic effects, we don't actually have any proof that the speed of light is impassible, just some theories that have yet to be proven incorrect (and probably never will be).

However, I still believe that someday, in the very, very distant future, the human race will manage to travel from planet to planet faster than light. We've just too clever and stubborn not to.

 

we'll definately be travelling to the planets. A few hundred years ago who thought we would ever walk on the moon...but we did it. Even if the speed of light is ever reached i doubt well find intelligent life because distant galaxys take thousands of years for there light to reach us. There talking about the future of long distance space travel maybe to create a wormhole, or they may possibly already exist in space but it would be technology way beyond us, it would be like a mediavel war hero going on work experience with a rocket scientist. who nos what the future holds

 

It is true (so far as we know at this point in time) that a photon has zero REST mass.

The mass of a photon(in motion, of course)

Is planks constant multiplied by the frequency of the light and divided by the speed of light squared.

Momentum is energy and energy is equivalent to mass. (Thanks Albert)

It's late and I'm not going on a search through the internet for facts that most of us are aware of already.





massless particles emitted from the sun will never have an effect on a solar sail, and we all know that solar sails work, which means photons can transfer their momentum to an object with mass, because they have mass, as defined by the famous E=mc2 equation.

 

Technically i think they believe a wormhole would also be a time machine, space and time being two of the same thing.But then arguments break out if you go back in time and shoot one of your great great great grandparents you wouldnt of happened, and you could only travel back to when time travel was created and the argument goes on. But time travel already exists like the GPS clocks having to be altered, its not a fantasy. When we know what happens at the singularity point of a blackhole, where the laws of physics are themselves broken , that is when i believe we'll use space to our advantage and leave the blue marble

 

When we know what happens at the singularity point of a blackhole, where the laws of physics are themselves broken , that is when i believe we'll use space to our advantage and leave the blue marble

I don't think the laws are broken, just stretched and taken to the absolute extreme beyond our comprehension. The laws may even have more portions that need added on that we don't know about, such as going from newtons laws to relativity. Just further extremes that need to be analyzed.

 

I found the solution ?

http://www.phys.ncku.edu.tw/mirrors...y/SpeedOfLight/Superluminal/superluminal.html

 

Wow!

Something that is going 99.99999% has tremendous energy invested in it, almost nuclear in magnitude.

Going .9999999C with respect to what exactly?

I can certainly find some quasar in the night sky which we are all going .9999999C away from. Now, which has all that energy, the quasar or us?


This next comment is not just directed a you Bill, but it is fairly obvious that even special realtivity creates as mjuch confusion as does QM. The only exception is that QM seems to have confused some of the folks that helped create it.

 

Relative to us. That is the point, everything is relative. Since we are the observers most things are taken as relative to us. All else is extrapolation.

But, and this is the big point, since we are the observers nothing can go faster than light from this point, or as observed from this point. It is also true of any other observation point, but this is the one we can take definitive measurements.

Fancy verbage doesn't get around the basics, the expansion of the universe is not a magic step around the fundamental laws. The math is consistent, verbage and philosophy isn't. It is one of the reasons I tend to dislike philosophical questions for their own merits.

I hope there are ways around FTL, such as wormholes, but wishful thinking isn't it.

 

But if we are going .9999999C relative to the quasar then it is going the same relative to us. Quasarians would be saying we are the ones with all the energy.

Trouble is, we can see one quasar to our left, receding at .9999999C and one to our right receding at .9999999C. Now, I ask, from our perspective, what velocity are the two quasars receding from each other? What about from the perspective of the quasars? How can you reconcile the difference? Which of the 3 of us is standing still? This stuff is not all that difficult, but you must be a very meticulous accountant to make it work out right.

Without getting into too much explanation about this, depending on the observer, velocities beyond C are possible in the universe between 2 objects. Just not mutually. A third party is required. Mitch's dad is right.

The energy you are talking about is only between the points of reference. Change one of the points and the energy changes. It only has significance in that way, and not in any absolute terms.

I can at any time declare that I am in flight at .9999999C from that first quasar, but my kinetic energy will not change one erg.

Your claim is only valid in the very specific case that you try to accelerate an object that is in your frame of reference to some velocity close to C with respect to that frame of reference. You will then need to invest a lot of energy taken from the supply in your frame of reference.

Here is a real fun thought experiment. You gaze at a billiard ball floating out in space trying to figure out how to accelerate it to .9999999C. As you are scratching your head, an alien traveling at .99999999C (note the extra '9') toward you spies the billiard ball. Now he's got another take on the situation. He say's to himself, "If I could just slow down that billiard ball I could have enough energy to run my house for a long time". So he builds and deploys a super-duper net that grabs and slows down that ball by extracting most of the kinetic energy out of it. You see what he does and get on the phone to him and ask, "Hey, where did you get all the energy to accelerate that ball?" He replies back "What do you mean, I got a ton of energy out that sucker by slowing it down! Who is right? Did the ball gain energy or did it loose it?

Anyway, It’s my experience that this is something it’s better not t try to change people minds bout. Kind of like religion, or magnetic fields. The subject is just too far reaching.

 

Uh, no, we discussed that earlier, with the 3 body problem in post #17. If you switch your reference to the quasar, the other jet still isn't going faster than light, it just has more nines. Again, it is relative to where you are looking from, not differential speeds. But the main thing is, no matter where your viewpoint is, C is still the limit. You can approach it forever, adding 9's to your hearts content, but never touch it. If you can't touch it, you can't go past it.

The theory still stands, it is reliable, and robust, and remains invoilate, no matter what the wishful thinking. There are things I don't understand about time slippage, but the speed issue is actually pretty simple. Two objects from your point of view that are moving together or apart greater than C aren't exceeding C from your point of view. The speeds you measure are still under C. More importantly, switch points of view to the other objects and they aren't exceeding C from each other either, but have a different numbers that will adjust accordingly.

The reason I am so sure is I have put a lot of thought into the subject, and took the time to learn the math at one time. I put a lot more thought into the subject than most. It is one of the subjects I would love to be wrong about, but the theory works consistantly and well.

 

No problem Bill. Think of it as you like.

Please don't put words in my mouth though. I never said the theory fails, just there are many that are confused by it and do not know how to properly work it.

 

Those relativistic effects again..

Approaching C, the length of the vessel shortens , explaining the meter stick trick. But the mass also increases (the current guess about mass involves interaction with Higgs bosons - if your motion involves interaction with more Higgs bosons, then mass increases) to the extent that any particle that makes it to C also has infinite mass. This is bound to be hard on the crew of any spaceship achieving that speed, not to mention the rest of the universe. It's hard to imagine the rocket motor that can accelerate a mass only slightly less than infinite.

This is a perfect example of the sort of confusion I am talking about.

This seems to imply that at least someone believes that Higgs bosons occupy some preffered frame of reference with respect to this observer. How about to another observer of the event that sees the vessel as slowing down? Will they claim that the vessel is encountering fewer Higgs bosons and therfore it's mass is decreasing? What is the vessel doing, encountering more, or less Higgs bosons?

So,
We have observer A, who sees the vessel speed up.
We have observer B, who sees the vessel slow down.
We have observer C, who is on the vessel and claims it's undergoing some change in velocity.

Any observation made by A, must be supported by the observations made by B and C once relativity is properly applied to those observations. This example is an easir one though. One of the frames of reference is special. The vessel's, it's dv/dt is non zero. However, the assumption that this must be hard on the occupants is a little off the mark. The folks at A might think those occupants are getting massive. The folks at B might think they are the biggest loosers, but the folks on the vessel will not have noticed any change in their mass once they correct for the instantaneous value of dv/dt.

Once relativity is properly applied you should see that only their mass relative to A increases, not their intrinsic (rest) mass. Likewise their mass relative to B decreases. However, A, B and C, should all agree that the intrinsic mass of occupants in C did not change if they have proper knowledge of realtivity.

You need to keep in mind that all things have a intrinsic, actual or 'rest' mass as well as a relativistic mass. That intrinsic mass never changes, the realativistic mass changes for every observer.

I do not think the mass - Higgs boson relationship was ever meant to explain relativisitc mass, only intrinsic mass. The relativistic mass ( which comes about as a consequence of the FitzGerald-Lorentz transform which is in turn derrived from the speed of light being set as an absolute limit and independant of the velocity of its source. The transform assures conservation of energy given this property of 'C' ) is entirely dependant on the observer.

 

Lack of proof is not disproof.

 

Tektronix has once claimed in their advertising that the sweeping trace on the screen of their high end scopes travels faster than the speed of light.

They may very well be correct, as it is relative. If I take a very powerful laser and shine it at Jupiter, then move it ten degrees in ten milliseconds (not impossible for a scope beam or very fast magnetic actuators), then I will have beaten the speed of light with the resulting beam.

Assume that the distance from Jupiter to earth is about 900,000,000 km. The distance moved on the moon is equivalent to tan(10deg) * 900000000 km = 158,694,282 km... or 1.58 million km/s, about 5.3x the speed of light.

Applying it to a scope beam... let's say the screen is 10 cm and the trace is set to 50 ps/div, that would mean that it traverses the screen in 500 ps and travels at 2 billion meters per second, which is 6.7x the speed of light.

So yes, relatively, beams of particles can travel faster than the speed of light (in this case photons and electrons) but they do not send information faster than the speed of light.

 

uhhh, no. I've heard the same argument with scissors, you have a point you think is moving faster than light, but it is an abstraction. The light doesn't gain speed. Imagine a stream of BBs from a BB gun and sweeping the gun across the heavens. You will have a stream of BBs, but the gaps between the pellets is the only thing that will increase as the stream forms an arc.

 

uhhh, no. I've heard the same argument with scissors, you have a point you think is moving faster than light, but it is an abstraction. The light doesn't gain speed. Imagine a stream of BBs from a BB gun and sweeping the gun across the heavens. You will have a stream of BBs, but the gaps between the pellets is the only thing that will increase as the stream forms an arc.

Yes, that is an important distinction. The beam isn't a physical object.

 

No, but it is a stream of particles. I think the BB analogy is pretty close.

 

No, but it is a stream of particles. I think the BB analogy is pretty close.

Yes, as it is not a physical object it is possible for the "concept" of those objects to appear to travel faster than the speed of light.