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This is the whole reason why we call it 'relativity'! There is no global unambiguous way to define an absolute velocity, so only the relative velocities matter. Everything else is just from a point of view. When one says 'Bob moves at 10km/h and Alice is stationary' they are implicitly defining a reference frame. Usuallay in day to day life, we define our ...


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Well technically speaking, time (or better say passage of time) is identical in two frames of reference that are not accelerating with respect to one another (i.e. at rest or moving at constant speed). So yeah, if an ant and an elephant are put on a missile and accelerated into outer space and back, they would have aged identically with respect to one ...


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Gravity is acceleration. Einstein's equivalence principle says that gravity (with the vector pointing toward the center of the mass) is equivalent to actual movement with acceleration pointed "outward". That's why we observe gravitational blueshift. Now, blueshift means that the frequency of the photon received is increased as compared to its frequency at ...


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Yes and no. Remember in special relativity whenever someone asks a question, they always are told to draw a spacetime diagram. The same thing happens in general relativity. If you want to see what is possible, consider drawing a Carter-Penrose diagram. For a black hole you can draw the event of a test particle crossing the event horizon. The past light cone ...


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So steam is caused when you have a supersaturated water vapor that cools and forms large suspended water droplets in the air. This is governed by the kelvin equation which you can read more about here: https://en.wikipedia.org/wiki/Kelvin_equation To get larger water droplets, or in your case a denser looking steam, you have two options: 1. you increase ...


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The model is good as a probability model for quantum mechanics, up to the "superposition", where you say: Nobody knows where is the red and the black card, so each card is red or black with the 50% of probability. In other words each card is red and black at the same time (superposition). No , just the state of the card is unknown, it is not half ...


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My question is, why doesn't interference occur with the observer here? Aren't there still probability waves between the quantum objects going through each slit, and shouldn't these waves interfere and create fringes of some sort? The results of any experiment when modeled with mathematics is absolutely dependent on the boundary conditions, which pick up ...


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With an observer there are no longer two probability waves travelling through each slit. There is a particle exiting one slit, which can be described by having some probability of where it will hit on the other side but there is no "second wave" from the other slit for it to interfere with. Another way to make it a little easier. If you imagine the ...


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"Virtual" is not a property of a particle at all. And it is not true that pure electric and magnetic fields are "made out of virtual photons" or that a combined electromagnetic field is "made out of real photons". A "virtual particle" is not a particle. It is an internal line in a Feynman diagram, which is in turn a graphic notation for a certain integral. ...



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