Physics quandry?

Question

Yes I'm sure I could just do some research on this to find out, but I'm bored and asking here.

If objects increase in mass as they approach the speed of light (with their mass being infinite at the speed of light), then would an object that achieves the speed of light (impossible, but let's say there was some loophole) have infinite mass? If so, would it have an infinite gravitiational pull? If so, would all the rest of the universe be drawn towards it at infinite speed? If so, would the rest of the universe have infinite mass?

Also, if something increases in mass as it approaches the speed of light, doesn't that negate the law of conservation of energy and mass, or is kinetic energy applied to acceleration converted to mass (thus explaining the increasing difficulty of accelerating a given amount of mass)?

Bob, don't we define mass as the resistance of an object to force? so then by definition that would cause the mass of the object to increase. The question is whether objects moving at relativistic speeds have increased gravity (and I guess whether or not that'd be a way of testing the graviton theory)

In retrospect, the force could remain the same on a reletivistic object, but more energy could be required in order to exert the same amount of force, so I guess that makes sense...

So, pretty much it's irrelevant, as it would take infinite energy to get something to light speed. My point on energy being transformed to mass was that for conservation of energy and mass to occur, the kinetic energy (Which is, what, mass times the square of the net velocity or something?) would be transfered, so assuming no change in mass, the increase in velocity would have to be the same for any addition of energy. If it isn't, then something's got to give, and that means that the mass would have to be higher.

Oh hey, Wiki gave the equation to determine the actual mass of the object given its rest mass. Nifty. Not sure of the accuracy.

Answer 1

(1) For an object with mass to achieve the speed of light, you must put in an infinite amount of energy. So if you assume that is possible, then yes, the object will attain infinite mass and become a blackhole that will suck everything in the Universe into it, but not at infinite speed. However, I see no point in explaining this because we have already made an "impossible" assumption (have infinite energy available to achieve infinite mass), thus violated the laws of physics. So any questions you have about what happens after the object attains infinite mass is moot because anything now is possible.

(2) Mass and energy are the same thing in different form. So if an object increases in mass, the mass must come from somewhere, and in this case, the mass comes from the kinetic energy being put in to increase the object's speed. So there is NO violation of conservation of energy and mass.

(3) Special Relativity tells us that the increase in mass is only as measured by us who are stationary on Earth. If you were on a spaceship that's traveling close to the speed of light, you will not measure a mass increase. To you the spaceship and yourself still looks and feels the same. Just as to people on Earth, the spaceship would look shortened but to you it still looks the same. And to people on Earth, time would seemed to have slowed down considerably on the spaceship, but to you everthing on the spaceship is still normal.

Answer 2

The conservation of energy (energy is neither created nor destroyed) is not violated. As you allude, kinetic energy is converted to mass-energy, but it is not destroyed. The whole E = mc^2 thing is essential to understanding modern physics. This famous relationship simply says that energy is a form of mass and mass is a form of energy.

In string theory, the theory is that finite vibrating strings take on the characteristics of all the fundamental forces and matter in the universe, depending solely on their energy, which determines the frequency they vibrate at. Thus, this little bundle of energy can look like an electron, for example, which has mass (inertia). Or, it can look like a photon, which has no inertia.

As to mass ---> infinity when v ---> c, infinite mass is not feasible. There is not enough energy in the universe (and the parallel ones next door) to bring a rest mass to infinite mass. But if one could, the universe would become one very large black hole...a singularity.

Answer 3

Responder Bob D is not correct: the mass does change as velocity increases. The energy required to cause that increase appears as increased mass. Hence the conservation laws (which actually should be called the conservation of mass-energy) are not violated.

Answer 4

You can learn the most by studying the behavior of objects near the speed of light.. Yes, it takes energy to accelerate an object. What law of conservation of mass are you thinking of? If the object you are accelerating is influenced by a gravitational field, that can increase the energy needed to accelerate.

I have yet to see a satisfying explanation of how the energy used to accelerate an object is converted into increased mass of the object. Yet, I observe the reverse direction of E=mc**2 in nuclear fission.

So yes, I would admit that 'physics quandry' is an oxymoron.

Answer 5

The energy required to accelerate further as you approach the speed of light approaches infinity. Mass doesn't change.

Edit: Mass is independent of velocity, the gravity an object exerts is also independent of it's velocity, it is speculated that a massive rotating object will cause 'frame-dragging' around it but this is theoretical. You are correct in that conservation of energy would be violated by mass increasing with velocity.

Answer 6

i don't know