r/AskPhysics

Ok, this is a nerdy question, but the thought has really been bugging me recently.

I know that Star Trek waves away relativity with the made-up Heisenberg Compensator and allows for faster-than-light travel with just normal time change. I'm curious if the Enterprise came back to Earth, say from Vulcan, which, according to canon, is in 40 Eridani (16.5 light years away), the crew could look in whatever equivalent of the James Webb Telescope and see themselves before they returned. So, in a sense, they would be in two places at once.

At singularity does any mass exist?

Is it inevitable that a black hole keeps going up in size over ‘time’ as it keeps gobbling up its surroundings? (I couldn’t help use ‘time’ in the sense we understand it, and I don’t know what time means to a black hole).

If it is all due to mass, isn’t there a limit for density? If not, what chemical element would the mass be?

If we were to get inside the event horizon would everything around us look bright or dark?

I'm entering 12th grade, and I was planning to major in computer science. However, with the current high unemployment rates, I'm having second thoughts and considering a switch to physics instead.I'm not sure now what kind of jobs you can get (coming from an average student) if I'm interested in theoretical physicsics.

The singularity is a point with zero volume, but does it contain all the black hole mass? Are the singularities of a 1e3 solar mass and 1e10 solar mass black hole different? If a black hole acquires mass by slurping a star then does the stars mass instantly add to the singularity? And then is the space between the event horizon and singularity just empty? It doesn't make sense. Also, is there a chance that a black hole is just a 'normal' object like a neutron star, that happens to be too heavy to reflect or emit light?

So I recently read Project Hail Mary and watched the film, and first of all, if you haven't at least watched the movie yet, what the heck are you waiting for?! lol. But anyway, one of the plot points of the story is that because Rocky's species was apparently completely unaware of Relativity, they ended up bringing far more fuel than they actually needed to reach Tau Ceti, because they were assuming that Newtonian physics was the way the universe operated. As a result, Rocky explains that he was baffled both that the trip seemed to be a lot shorter than he expected, and required far less fuel.

But shouldn't that have resulted in them having LESS fuel than they needed rather than more? Since the closer you get to the speed of light, the exponentially more energy it requires to go faster/keep accelerating, whereas under Newtonian physics it would be linear? Normally Andy Weir does his homework regarding stuff like this, so I want to give him the benefit of the doubt. But I don't understand how this could be possible given my admittedly layman's understanding of Relativistic physics.

I am quite comfortable with the notion that the universe is infinite, and that the early universe (during/right around the big bang) was also infinite.

But I am confused by how we can say that the universe was infinite and that matter in this infinite universe was uniformly spread out. Wouldn’t this imply that there is an infinite amount of matter in our universe also? This seems to be contradictory.

Any finite amount of matter in an infinite universe either needs to be non-uniform and clumped, or infinite which allows it to be uniformly spread. The uniform spread of matter seems to be well tested with CMB observations and Baryonic Acoustic Oscillation measurements. But infinite matter seems to be a blaring contradiction to reality. Is there anything I am misunderstanding? Anything else I should research on?

Temperature is the internal kinetic energy of the molecules. Basically the speed/rotation.. of molecules and it controls the chemicals reactions.

Why cant you bake a bread in room temperature as long as you wait for a long enough time?

Is 14 billion years since the big bang like an infant, or is it a middle ager?

I read some clickbaity articles that are all about the end or death of the universe, makes it all sound very old. Before our sun there were endless other suns already burnt out, and all that.

Our solar system formed what, 5 billion years ago? So it's like one third of the universes' lifetime. That doesn't seem much.

I wonder what astronomers would have seen five, ten billion years ago when they looked into the skies, deep into the universe. It must have been a lot denser populated with stars, a lot brighter.

Weird when you think about it.

I just need to know form someone why and how this happens for an essay also it might just be fun to know why

I have set myself a goal of building a fusor in 2 yrs. I am looking for any help, but especially I am looking for book suggestions, websites, articles, everything I need to know​ to build a fusor. I hav2 always been interested in physics, but I need a solid base not just a patchy and vague sort of understanding. Even if you can't give me any concrete suggestions, I would appreciate a detailed outlining of all the fields necessary. E.g, high voltage, vacuum, plasma, electromagnetic fields... these are just a few broad ones, i would really appreciate more detail if possible.

Thank you all very much in advance!​

Okay so I need to take physics for my major and I only needed one which was college physics. I decided to knock it out this summer and get out of the way. My advisor recommended me to take physics from straighterline and my credits will transfer if I passed the class. A few days into the course, I noticed a lot of things that I saw in my previous calculus classes. I was confused and I googled, turns out I am doing calc based physics. I am terrified and I am unsure if I can pass this summer class. Its completely online, there isn't much online resources provided with the website. Please send me any worksheets, YouTube, anything so I can learn and pass.

Anything tips will be greatly appreciated!!!

Hey! I am a student in high school and recently got an opportunity to join one of the most prestigious university for technology in my country for summer internship. They asked students to give ideas on things they can research in. I recently was exposed to the idea of emergent complexity and read a good chunk of stephen wolfram's A New Kind of Science, and got to learn about cell automatas, and they spiked my interest and I am thinking about having my research proposal as 'Study of Increasing complexity, and affected computation in higher dimensional cell automata' is this good? And how can I present it to them? And Any general questions they might ask? ( ps. Im sorry for any grammatical errors:p)

Hello! Im a lowly highschool physics student and was wondering if anyone could help me out for my studying…

“There is a loop carrying current in a clockwise direction. Assuming there is a magnetic field pointing to the right, describe the magnetic force acting on different points of the loop (top, right side, bottom, left side).”

I’m just confused how the field and current are parallel at certain points? Another version of the question had the field pointing out of the page which made a lot more sense because my fingers actually can bend that way…

Anyways if anyone could help explain this question to me and help me further my conceptual understanding on magnetism i would DEEPLY appreciate it😎😎

For example if you’re traveling so fast and come back to earth? Say 70 years, how come one twin has gray hair while you don’t have gray hair. Wouldn’t you both be like 70 years old? Like I don’t understand it at all.

I don't expect it to work completely 1 to 1 with the real solar system, obviously, but is there a decent sort of working, physical small scale model that recreates our solar system physics that I can learn about/watch a video of anywhere?

I'm writing a Sci-Fi book that's grounded in enough experimental and theoretical physics to be considered theoretically possible---I've already made up my mind on that, so any attempt at dissuading me will basically end up in an 'unstoppable force meets an immovable object' scenario (unless there's a plausible reason beyond just "it's impractical" behind the claim).

Also, I wouldn't call my book Hard Sci-Fi because that implies that the book is more focused on science than a story (or something like that).

Anyway, here's my idea:

As stated above, my plan is for people to be charged with static electricity upon entering a ship, with it having flooring, walls, ceilings, and other electrical components with equal and opposite charges (the fewer electrons that need to be exchanged, the more explosive the reaction---I really hope I don't have my sciences mixed up; perhaps there is such thing as too much research) to the people, so as to prevent any bursts of lightning (assume that electrical components are properly insulated and stuff). So, using a powerful electrostatic generator (something that already exists) to provide enough downward force for astronauts would (hypothetically) certainly be within the realm of possibility, especially for a hyperadvanced Sci-Fi society (which would certainly have the capabilities of making an efficient wireless electrostatic generator).

So what do you guys think? I've already ran this sort of thing by a Sci-Fi Subreddit, and a couple of them claimed that such a thing at least seemed like it could work (initially, I thought of using magnets with charged astronauts, but one guy pointed out that magnets wouldn't be necessary with static electricity already existing). Anyway, I figured that also getting a general consensus from a Subreddit more likely to be filled with physicists, particularly people with more knowledge of physics than me, would be a good idea.

If I’m not mistaken no known interactions fit such a description, as while the weak interaction is mediated by massive bosons of different masses the W and Z bosons are also different in the sense that the W boson is electrically charged while the Z boson is electrically neutral. I know that while there don’t seem to be any gauge bosons that only differ in mass there are particles that seem to differ only in mass. For instance the only difference between electrons and muons is their mass and what follows from differences in their mass, and similarly the only difference between the up quark and the charm quark is that the charm quark has a greater rest mass than the up quark.

So I was wondering if QFT would allow for an interaction mediated by different gauge bosons that differ only in their rest masses that differ by multiple orders of magnitude even if there are no known interactions to fit such a description.

I have thought of an idea that I would love to ask how feasible it is. 

The concept rests on the fact that water pressure would overcome air pressure. 

You would have a system that is locked in heightwise, to allow for tidal flow into the system. 

This water would run through the system through turbines and generate electricity and exit through the air pocket at the bottom of the system.