Is this one better?
Part of the problem is that the words “mass” and “energy” are used in a few slightly different ways in Relativity.
If I’m not too mistaken here, when an atom has a jump in the electrons from a higher energy level to a lower one, a quanta of energy is given off as a photon. A photon is essentially massless. So light does not equal loss of mass.
If a photon had mass an incandescent light would explode.
Except I think that might be the wrong question. The real question is whether the atom losses mass when it goes from a higher energy state to a lower energy state. I think that the Wikipedia entry quoted by Magnet* above suggests it does: “Whenever any type of energy is removed from a system, the mass associated with the energy is also removed, and the system therefore loses mass.” Going from a high-energy state to a low-energy state implies a loss of energy, and hence seems to imply a loss of mass. The fact that the proton it produces itself does not have mass does not change that dynamic – it simply means that the proton is the energy that has been removed from the atomic system.
- Magnet: With all due respect, I think you should consider naming yourself after a stronger force. I mean, (electro)-magnetism is just so . . . weak. Amirite?
Right, you can’t “generate” energy. You can move it around. With it, you move some mass. I think the wiki examples are helpful in this regard, since compressed springs and hydroelectric dams have little to do with kinetic energy.
He’s just posting in this thread so someone will inevitably ask him how he works.
False. Long story short, this confusion stems from the popularized version of Einstein’s mass/energy equivalence equation being somewhat simplified.
Right. Just because a photon has no rest mass doesn’t mean it’s massless. Energy has mass and vice-versa as described in all those cited equivalence articles. The total mass-energy of the atomic system decreases when the electron cloud collapses to a lower energy state and emits a photon.
Let’s kick this up a notch–
Given that mass is a function of velocity, and that all motion is relative, that means by changing my velocity, I’m not only changing my own mass, but also the mass of all other matter in the universe.
Yeah, that’s clearly wrong, and has something to do with inertial reference frames yadda hey hey vey, but I’ve never been able to wrap my mind around it. Basically, how does the universe “know” who’s accelerating and who’s standing still? Why does the twin in the spaceship age more slowly than the twin on Earth and not vice-versa?
Strong, weak, it’s all the same when things get hot.
When you accelerate, your mass increases and the total mass of everything else decreases by the same amount. This is true regardless of your frame of reference. However, the amount of change depends on the frame of reference, and there is no “right” answer. Likewise, the total energy of the system (you + everything else) is constant, but its value depends of the frame of reference.
Why does the twin in the spaceship age more slowly than the twin on Earth and not vice-versa?
As long as spaceship-twin is drifting away from Earth-twin, both will observe that the other is aging more slowly. The only way to make a side-by-side comparison is for one twin to turn around and catch up with the other. Since the Earth doesn’t have a steering wheel, let’s say the spaceship turns around. To reverse its motion, the spaceship must change its frame of reference, and if the ship is fast then this will require a great acceleration. Acceleration causes time to slow down. Therefore, spaceship-twin will observe time go into fast-forward on Earth while he fires his megathrusters. Earth-twin doesn’t need to accelerate, and doesn’t experience this effect. By the time the spaceship lands, both twins will finally agree that spaceship-twin aged less.
Basically, how does the universe “know” who’s accelerating and who’s standing still?
The universe doesn’t know who’s moving and who’s still. It also can’t tell the difference between the force of gravity and forces of acceleration. They equally glue you to your seat.
That means that if spaceship-twin parked in front of a black hole, which has a great gravitational force, he would observe his Earth-twin go into fast-forward just like when he fires his megathrusters.
This next part tends to blow my mind:
Imagine spaceship-twin is freed from the black hole and is preparing to go back to Earth. He fires his megathruster and is pushed to floor. The stars fall behind him. And he thinks, “Am I even moving”?
There’s no way to find out. You see, maybe the stars are all literally falling down. He could be the last stationary object in the galaxy, hovering on a column of rocket fuel as the Milky Way falls away. He can’t even tell by scanning the area for galaxy-devouring black holes. According to Einstein, gravity is not a force. It’s just the shape of spacetime. It may look flat where it happens to be empty, but that’s not guaranteed. Just because you’re falling, it doesn’t mean you’re being pulled by another thing. It just means you’re on a local precipice in spacetime. So he sits, and ponders until his thrusters stop, and he’s back to being weightless in space. Or maybe in free-fall.
Yeah, the main issue is one of symmetry. The person on Earth and the person in the rocket ship - assuming the rocket ship has constant velocity - are in a symmetrical situation. (Well, almost. The person on Earth actually experiences acceleration due to the orbit of the Earth and the gravitational potential of the Earth, but this effect is negligible.) Once the rocket turns around and accelerates, the symmetry is broken. That’s where the crux of the “paradox” occurs.
Gotta say I’m learning more from this thread than I ever did in school. In a “gaming forum”. Rock on you folks.