Recent content by jartsa

Oh. But maybe in the special case of a flashlight shining to the direction perpendicular to its motion they agree? In a photon-gas bag frame the energy from the flashlight is increased increased by gamma(v). In a flashlight frame when the light emitted by the flashlight is stored into a bag...

Let me replace photocell by a photon-gas bag, into which the light emitted by the flashlight gets trapped . (it's simpler that way) Using bag frame: High energy object (light) collides with a parked bag. Bag does nor budge, because of its high mass (a simplification). Collision is inelastic...

I don't know if there was any mechanism. We just used one frame, and then we used another frame. When we launch a sack full of photon-gas using a catapult, then the mechanism that increases the energy of the photon gas is the catapult mechanism. (Energy comes from a spring) And now the same...

Two identical flashlights glued together, so that they shine to opposite directions, is a such thing that its velocity does not change in any frame. So let's use that thing. Let's say the thing is at rest. And we let it shine until batteries are empty. And then we change to a frame where the...

So why not use conservation of energy in lab frame? Electric energy of a moving charged capacitor goes from one place to other place, the amount of energy does not change. Can we make a simplifying decision that the moving thing is not a rocket, meaning that its velocity does not change?

The title says "do observers always agree on the number of waves in a beam of light", but it was actually a pulse of light, according to the text? Right? I did not read carefully though. To be sure, I consider both cases: Of course observers always agree on the number of waves in a pulse of...

Instead of being confused about reciprocity, you should imagine a scenario where observer A is confused about reciprocity. A says: B moves and B's clock is slow. My clock is normal. Why the heck does B think that my clock is slower than his own clock? The task is now to explain the thoughts...

In the planet frame math is easy. Just a super energetic particle (shuttle) passes the planet.

First one. In the frame of the shuttle there exists gravito-magnetism between the sun and the planet. (Let us keep in mind that the speed of the solar system is ridiculously close to c in the frame of the shuttle) (It's less weird in the frame of the planet)

With its rest-mass, helped by extreme gravito-magnetism, perhaps? Can I say that, moderators? Maybe Ibix can understand?

Well, hmm, tidal force on rocket fleet placed so that the rockets are symmetrically at the opposite sides of a black hole, experiences a tidal force that compresses the fleet at force that goes to infinity, as the distance between rockets approaches 2rs. I used a very large object, the fleet...

You said pull of gravity goes to infinity, but not tidal forces. I asked how can pull of gravity go to infinity without tidal forces going to infinity. Seems impossible to me. I mean, I meant to ask that. I used as an example a body experiencing an infinite pull of gravity, said pull not...

If an observer lowers a box that contains light, using a rope, towards a super massive black hole, from infinity, we know that the trajectories of light beams inside the box become similar to trajectories of light beams in a box in a very strong gravity field. We know this, because we know that...

If the left side of your body is pulled with infinite force to one direction, and the right side of your body is pulled with infinite force to slightly different direction, then is there not an infinite tidal force?

Force is arbitrarily close to mass multiplied by surface gravity, when a test mass is hanged arbitrarily close to the horizon using a rope, the other end of which is at infinity. By force I mean the force felt at the upper end of the rope The rope is of course massless. I mean small rockets...