Does the Light Speed Limit Only Apply to Information?

does the light speed limit only apply to information?

as it turns out we only get one value for the speed of light. About 300,000 klm per second that is the constant or limiting factor, in quantum theory a hypothetical partical called a tachyon has been postulated. It in theory would move faster than light, that is if it existed and would allow faster than light signaling so hypothetically you could receive an email before you sent it, the universe is not filled with causality problems such as this and that is pretty good evidence that these particals are not real in fact there have never been any found and if there were it would bust einsteins constant, for more than half a century people have tried to bust einstein and be the next genius but so far this constant speed 300,000 kps stands unbroken.

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Consequence of approaching infinite mass for near-light speed particles

To your question about "gravitational mass": in General Relativity (GR) this is a very very delicate point. The concept of a "gravitational mass" is not trivial in GR and one needs to specify very precisely what one understands as gravitational mass. First of all "mass" is not governing the curvature of space: the energy momentum tensor is. So if you are interested in the gravitational field of a massive particle moving very fast one would need to solve the field equations with the energy momentum tensor of this particle. You can NOT use lets say the Schwarzschild metric (SSM) and put in the "relativistic mass" of your particle. First the concept of relativistic mass is not a good one 2. the SSM does not hold at all for moving particles/sources. It holds only outside a static, spherical symmetric object. I did not find a reference for the gravitational field of a relativistic moving particle but one can for sure not use the SSM. The gravitational field will depend on the particles four-momentum, it will be non static and not spherical symmetric, since the direction of motion is an axis of anisotropy. Maybe one can work out some spatial axis-symmetric solution for that problem choosing a coordinate system in which the four momentum becomes $p^alpha=(p^0,0,0,p^3)$ but I have not found/ calculated one. Apart from that I would assume that even at relativistic speeds the curvature caused by single massive particle will be relatively small, since even at very high speeds the energy/momentum of such a particle would be rather small.This gravitational mass against infinity picture does not hold: its all about the energy momentum tensor and you will not get this one to infinity with just relativistic speeds.That being said one more point towards "gravitational mass" in GR, to be specific in the SSM. In the SSM the "gravitational mass" comes up in form of a integration constant and from the Newtonian limit we see that this constant can be identified with the classical/Newtonian gravitational mass. This is one special case where classical gravitational mass has a meaning/equivalent in GR. It is one of very few cases where the concept holds some meaning in GR. In general this is not the case and one can define a multitude of "masses" (integrals over very different objects)

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You're in a car travelling at the speed of light...?

First, SLOW DOWN!! Come down to the Speed of Sound. Suppose that you were standing near a train track, and a high-speed Bullet Train was coming at you. It started blowing its whistle while it was one mile away, and continued to blow the whistle until it was one mile past you. Consider: When the train is one mile away, you HEAR the sounds wave coming at you MORE FREQUENTLY because of the speed of the bullet train. When the train is right in front of you, you hear the sound waves at their correct frequency. And as the train moves away, you hear a the sound waves coming at less frequently than before. But did THE SPEED OF SOUND change? NO! What changes is the FREQUENCY of the sound wave, not the SPEED. So, what you hear is a dropping pitch -- ooooooWEEEooooo -- as the drain approaches, passes, the goes away. This is called THE DOPPLER EFFECT. You can hear the same thing if you listen to the Indy 500 on Memorial Day, or pass a truck on the highway. Now, back to light speed. When you turn on your headlights, the light leaves the headlight at the speed of light. YOU would see no difference. But to someone on a planet in front of you, HE would see your headlights, BUT AT A SHIFTED FREQUENCY. The light would be at a HIGHER frequency than the "white light" from your head lights. You head lights would appear much REDDER to him, probably in the infrared or higher region, and he would need special equipment to see you. To someone on a planet BEHIND YOU, he would see your lights at a LOWER freqeuency then the light from your heads lights. You head lights would appear much BLUER to him, probably in the ultraviolet or lower region, and he would also need special equipment to see you. in ALL THREE CASEs, the SPEED OF LIGHT remains the same, but the FREQUENCY of the light waves changes. When the frequency INCREASES, we call it RED SHIFT. When the frequency decreases we call it BLUE SHIFT. Astronomers use this very principle to determine of any given star is moving TOWARDS us (red shift) or AWAY from us (blue shift). The Doppler Principle is very precise. We can use Red Shift and Blue Shift to tell HOW FAST a star is traveling, and, using lasers or radar waves, exactly how fast your CAR is traveling!