Recent content by Green dwarf

Thank you, @martinbn, @PeroK and @Ibix.

By a clock outside the event horizon, things slow down as they approach the event horizon and never quite reach it. From an outside perspective, there shouldn't be anything inside a black hole. Everything should be just outside the event horizon. There shouldn't be a singularity.

Saying the particle has no position operator - is that different from saying it is not at any location or that it is nowhere?

Is it at a single point half way between the two stars, or is it in a superposition of locations forming a hemispherical shell around the sun, or does it just not exist at all until it interacts with a particle in Alpha Centauri?

Thank you. That's a new idea to me - some localisation. Going back to my original question about the photon, would the same apply there, so that all directions are not equally probable?

Thanks DrClaude. Presumably all particles interact constantly with gravity. Would that mean that they are always localised?

Let's say a uranium atom floating in space emits an alpha particle. Presumably, the alpha particle travels in a superposition of all possible directions until it is detected. (I'm guessing that a 'detection' can be an interaction with another particle, not just an interaction with a conscious...

Thank you DrChinese. Your answer makes sense. If, instead of emitting a photon, the electron is knocked out, does the electron travel on all directions too? Would the same be true of the proton? What about a larger atom or a molecule or a speck of dust or a pebble?

If a lone hydrogen atom in space emits a photon, is it emitted in a particular direction or in a superposition of all directions?

Thank you everybody for your responses. As I expected, the situation is much more complicated than the simple model I was imagining. I really don't understand general relativity and probably never will. At 70 years of age, I'm probably better suited to growing beans in my vegie patch. I do run...

Thanks Dale. I'm wondering too, would there be any truth in the idea that the matter in a black hole would form a thin shell on the event horizon because matter falling in would stop there (from an outsider's perspective)? One might think that as the black hole grows, matter inside it would then...

I'm wondering is whether it is the gravitational potential (in J/kg) at a point in space that determines the rate of passage of time, or whether it is the gravitational field strength (in m/s2). To clarify, suppose you had a very heavy hollow spherical shell. The gravitational potential would...

Thank you vanhees71. Can I ask a further question? My understanding is that a wave function could in theory be defined for the whole universe and that this function evolves in a deterministic way. Does that mean that the uncertainty in the system doesn't increase over time? The alternative being...

My understanding of quantum theory and information theory is that, given complete information on the state of the universe at present, it is possible to predict its state at all times in the future and past. 3 questions: 1: is this true? 2: how are quantum-probabilistic outcomes accounted for...

Thank you everyone. Being a science teacher and not a physicist, I have been influenced by science textbooks for school kids which tend to classify energy, though I have never been quite comfortable with the classifications offered. Hence my initial question. It's actually quite a novel idea to...