Relativity and a Solar Sail

A few technical details related to this thread ...

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Several decades ago the concept of relativistic mass increase was dropped in favor of the concept of relativistic momentum increase (p = gamma * (m * v)). Mass is once again recognized as invariant, even at high velocity/speed. A lot of people learned it the old way.

Of course once you get much above 0.99c the veolcity of a body becomes effectively invariant also. This means that all of that extra energy ends up in gamma. Or maybe in the multiplication signs. Weird.

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A number of preliminary engineering studies have been done on intersteller space missions using light sails and giant orbiting lasers for propulsion. The laser collects energy from Sol to power the beam, which pushes the space craft to its destination. A scheme for using the laser here to decelerate the space craft there has even been worked out. It involves releasing a portion of the sail at the mid point of the trip to act as a remote mirror to reverse the direction of the beam at the space craft.

The particle wind from Sol and other stars plays no role in these schemes. It seems to me that it COULD be used for local propulsion via a sail-like device, but I've never seen a proposal to do so.

Regards,
LB

Dear Larry,

Excuse me, I have no intention to be offensive, but what you are saying is a nonsense:
- m=gamma*m0 where m0 is the rest mass of the body
- gamma is dimensionless, and in physics has no meaning other than that of a coefficient, least of all capable of absorbing "all that extra energy"

Please, tell me how the autors of the "solar sail" intend to hold on place the reflecting mirror at the midpoint? Chaining it to the surrounding planets if available? Or, maybe some turtles are necessary...

There is one possibility which could work, however - the so called "photon jet". Much like normal jets, but using light instead of mass flow.

I disagree with the contention that there is no ether. Light is motion in the form of a wave. The wave cannot propagate through nothing. It can only propagate through something: ether, medium, aether, call it what you will. So far, we have been unable to detect the particles of this medium with our current technology. However we do detect the macroscopic effect of this medium.

Conventional physics states that there is no ether, and that there is no detectable resistance to movement in the proposed ether. Wrong! Particle accelerators must add incredible amounts of energy to raise the velocity of a proton (or equivalent) when the proton is near light speed. Conventional science explains that the mass of the proton has dramatically increased. Really? An alternate explanation is that the resistance of the light carrying medium has finally become significant because the proton is nearing light speed. You cannot reach/exceed the speed of light because the force you are applying to the proton is electromagnetic force, which can only propagate at light speed.

The whole matter is analogous to why a propeller driven aircraft cannot exceed the speed of sound. However, put the aircraft in a dive, where the force of gravity now acts as a propelling force, and the aircraft can exceed the speed of sound.


Gregg Wilson

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>
Dear Larry,

Excuse me, I have no intention to be offensive, but what you are saying is a nonsense:
- m=gamma*m0 where m0 is the rest mass of the body
- gamma is dimensionless, and in physics has no meaning other than that of a coefficient, least of all capable of absorbing "all that extra energy"
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
Like I said, weird. (No offense taken.)

If mass actually did increase you could detect it with an experiment. This is (part of) why they moved away from the concept of mass changing with speed. But if velocity also becomes (essentially) constant ... where does the energy go?

The problem with relativity is not that it's hard to understand, but that it's hard to believe. The basic concept of relativity (everything is relative) is obviously correct, but we may not yet have figured out some of the details, or know exactly what they mean in the physical world. We certainly have trouble explaing them to ourselves.

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>
Please, tell me how the autors of the "solar sail" intend to hold on place the reflecting mirror at the midpoint? Chaining it to the surrounding planets if available? Or, maybe some turtles are necessary...
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

The released portion of the sail is free floating and continues to accelerate, always staying ahead of the space craft.

[Gregg]
[Light is motion in the form of a wave. The wave cannot propagate through nothing.]

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That was Newton's dilema some senturies ago - he concluded the light consists of particles. We know now, that the light is both, and, according to de Broglie, everything is both. That's why the electron microscopes work.


[Gregg]
[Conventional physics states that there is no ether ... Wrong!]

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Conventional physics simply says we do not need the ether concept to explain what we see. You want to replace the relativistic mass increase with relativistic ether properties? No problems. The final effect observed is all the same. But then you have to describe the ether mathematically, make it consistent with all observations, and finally make some important prediction. Then you wait for some experiment confirming it, meanwhile answering unpleasant questions like "What about the stellar aberration?" or "How is it that the light travels with the same speed in all directions?" and so on.

[Hal]
[Conventional physics simply says we do not need the ether concept to explain what we see. You want to replace the relativistic mass increase with relativistic ether properties? No problems.]


So the actual physics of reality does not matter, as long as the equation is accepted? Let's see if that is true:

Conventional:

There is no medium for light waves. Once you have achieved a vacuum within the particle accelerator, we are left with NOTHING. Okay, we begin to accelerate the proton. We have to add massively more energy to get higher proton velocity, because the proton mass is increasing as we approach light speed. Let us not be faint hearted. We shall commit all of the Earth's energy to this proton. Now the proton velocity is only a gnat's ass short of light speed. According to the relativist equation, the proton mass is now a vast multitude of the mass of the Earth. In accordance with the universal law of gravitation, the proton causes the Earth to implode upon the proton. As the matter of the Earth accelerates to almost light speed during this collapse, the mass of the Earth becomes vastly greater than the solar system. The solar system implodes. The universe implodes on our proton. The law of gravitation demands that the implosion velocity exceed the speed of light yet the relativistic momentum equation prohibits that.

Alternative:

There is a medium that light waves propagate through. As we increase the proton velocity near light speed, the resistance to motion by the medium begins to be significant. It does not become infinite, but becomes very large but finite. Finally, we cannot get the proton to exactly light speed or faster, because the electromagnetic energy pushing the proton cannot propagate faster than light speed. The participating scientists are depressed by their failure to reach light speed. The Earth and the Universe remain intact. No entity or property became infinite.

Laws and equations are human inventions that attempt to represent reality in a very simplistic, cartoon like way.

The fact that light propagates from a moving source at exactly the same speed in all directions is powerful evidence that light is a wave and not a particle. The velocity of propagation is determined by the properties of the medium, not the moving object.


Gregg Wilson