Relativity

A comment in the ongoing "Nature of Time" thread made me wonder what gravity would look like if the Galilean version of Relativity was correct I have seen the animations depicting Galilean spacetime diagrams and wonder whether or not they can be extrapolated to a model of gravity in a similar way to how AE moved on to GR from Special Relativity. Just to say,I am not attempting to attach any credence to Galilean Relativity. I just wonder if that model might be stretched to incorporate a kind of Galilean General Relativity and what "Galiliean Gravity" might look like.

I came across this by chance the other day, and felt that this is a particularly good explanation of the meaning of “metric” in the context of GR, so I thought I’d share it here for whoever is interested: Some nice visualisations in there. Also, the other GR-related videos on this particular channel are quite good. No particular point for discussion, I’m simply sharing this for all those who wish to learn more about this subject without having to dive too deeply into the abstract maths. Particular emphasis on comments from time stamp 19:40 onwards (on coordinate vs proper measurements), as that’s were all those many common misconceptions arise. ED…

The question is, if time passes by slower close to heavy masses, what effect does that have on light passing by a heavy object (black hole). According to Einstein, all processes take place slower and, although light keeps travelling at the speed of light, we (from our point of view) should see that this light should pass by slower. In the intergalactic space, however, the total opposite should happen. As time goes by faster and the light there also passes by at the speed of light, from our point of view we should see this light travelling faster than the speed of light as we know it. If this is real, the galaxies we see, should actually be slightly farther away from us, b…

Hey folks, i am an S1 student in Scotland ( it should be 7th grade for the usa ). I've been asked to write a 6 pages essay about General Relativity and it's implications. First, i looked some documentaries on Youtube to understand better how space is connected to time and how both are not absolute as newton described. I think i understood what Albert is trying to say pretty good now. What i don't get is how is it possible that gravity bends space-time, is it the matter that bends it ? or the relation of the mass and the space-time, like in the classic view of gravity ? or does spacetime alone "do the job"?. One last thing i don't really understand in …

If any point in the spacetime model is specified wrt any reference point is it inevitably the case that that point can only ever be an approximation to any physical activity that actually takes place there? If so is this because of theories like the Uncertainty Principle or does it simply follow from the spacetime model itself, because it models both position and time ,as well as (I imagine) that at the most detailed level that all things are in relative motion no matter how we try to set up any scenario that might illustrate processes at rest to each other?** **Not completely sure if that is completely accurate and I think Studiot recently disa…

What is gamma factor of object, which is freely falling into black hole, on event horizon?

I'm interested in why less time passes on the spaceship than on Earth in the twins paradox of special relativity, and the only explanation I've ever seen is that the spaceship takes a "shorter path through spacetime". By "explanation", I mean a proposal for a physical mechanism that would slow down the time evolution of the spaceship's wave function, or some other theory that provides a framework for understanding the phenomenon. I'm not interested in the quantitative aspects of the problem; I take Lorentz's transformation equations as given. I may be dumb, but I'm not that dumb! 😄 The only reason I use the twins paradox as an example is because it eliminates the arg…

From the thread Sending an instantaneous signal: No, it’s not. If you wish to discuss it, open your own thread on entanglement, so your misconceptions can be addressed. Could someone please do me a favor and address these misconceptions? I'm afraid I don't understand them. By "using entanglement" I meant using entangled particles to send an instantaneous signal, as the OP had asked about (or, more speculatively, possibly using whatever process underlies entanglement sometime in the future, if such a process exists and we can learn how to use it).

(wasn't sure in which sub forum to put this one) I have been trying to follow (some of) the ongoing entanglement topic and this has occurred to me. Suppose there was a way to look for entangled particles (coming from deep space) that showed a pattern indicating that they were created deliberately ,could that be an indication someone was sending a message from the location of the "twins" of the particles we had just encountered ? Could we answer by locating the source of the signalling and then finding a source of entangled particles midway between us and them and encoding them?(they would reach us and our interlocutors at the same time)…

Hello, I'am new here and in search of a simple explanation to a rather dull question : in the classical Lorentz first equation to translate from O to O' referentials we have x' = gamma.(x - vt). But v should be x/t, hence x = vt and we have x - vt = 0 which is meaningless. No amount of litterature I read on the subject could enlight me, I'am trying to write simple numerical exemples but this point is a non-goer.

In this paper there will be discussed a re-imagination of logical categorization, based on modern data from quantum physics for the reason of obviating the limitations, paradoxes, and arbitrary parameters found to characterize a said physical reality. If you are unfamiliar with categories: category, in logic, is a term used to denote the several most general, or highest types of thought forms or entities, or to denote any distinction such that, if a form or entity belonging to one category is substituted into a statement in place of one belonging to another, a nonsensical assertion must result. Categorization shaped classical logic, which shaped mathematical logic, w…

I was about to reply to this saying basically that I think that space is expanding at all scales, but on smaller scales (even between Milky Way and Andromeda), gravity overwhelms expansion so that the galaxies are "moving through" space relative to each other faster than expansion can separate them. A google search shows only results that disagree with my view, and seem to suggest that if two things (in an otherwise empty universe, say) aren't separating, then I guess there's no meaningful way to say that that space is expanding? If two more-distant galaxies are separating at an increasing rate due to expansion, people use phrases like, "gravity has no effect at those dis…

hello i would like to ask if there is a way to implement black holes, wormholes, and warp drives on antennas, rf circuits, and signal processing. thanks very much.

Gravitational potential is only meaningful in some simpler metrics like Schwarzschild. Assuming our universe is flat on the largest scales, do we say it's flat because it has uniform mass distribution, and is that independent of the total mass? Then, assuming it's flat and that the big bang happened, theoretically it was always flat? Or is it flat specifically because it has very little average density, and wasn't always flat? If what I wrote above makes sense, you'd be trying to compare a clock in flat spacetime, to a clock in flat spacetime after inflation. Could it make sense to do it with a Doppler analysis? If you compared clocks at different plac…

Time is a dimension that always moves forward, never backwards. But as we move closer to the black hole, time first turns 45% and then 90% and time changes its axis. The question is where does the time go?

As a measure of a distance between objects does the term ,"event separation " mean exactly the same thing as "the spacetime interval"? (as the terms are commonly used) Do physical objects only exist in the framework of the events that went into making them up and changing them?

hello i would like to ask if circular polarizers generate wormholes and warp drives. thanks very much.

Twin paradox is a corollary of kinematic time dilation effect of special relativity, it is a thought experiment, which cannot be completed with current technology, can only be confirmed or denied by theory at present. Twin paradox usually has two moving objects (two brothers), incase more moving objects are added, then the chaos level of the result will be greatly increased, then some current solutions may be no longer in force. Here is a possible method to solve twin paradox in micro-gravitational field. The premise of this method is that the kinematic time dilation effect in the gravitational field will be affected by a coefficient of k. The kinematic time dil…

What might be the overall energy of the observable universe? Is it possible that ,to an approximation it might add up to zero? Since there is a universe beyond what we can observe that may mean we can never know the answer but are there any models that could be used to answer the question? (Are there as many possible answers to the question as there are frames of reference?)

We are told that there is a super massive black hole in the middle of our galaxy and that it makes no sense why the stars on the edge of our galaxy are moving as fast as they are. Scientists have recently seen stars that they believe are further away from us than should be possible to see. What if we are already inside the event horizon of our galaxy's black hole? It would explain why everything is red shifted.

I understand that spacetime curvature is mathematically modelled as a local effect. But the effect of gravity is felt at great distances Is it necessary for all the local spacetime curvatures to be summed geometrically for this large gravitational field to be modelled? If so,is there some technique for doing this ? Suppose we are looking at the curvatures produced by the moon and the earth and we pick a point midway between the line that joins their respective centres,how would one calculate the curvature due to the earth and the curvature due to the moon at that point? And how do we add them?

These equations were made for a upcoming work of fiction that my sister is writing. My task is to create something that resembles math or equations consciousness in its various forms. I am aware that there is an advanced equation for the wave function. this is less about that and more about how we all agree what now is and how does time dilatation effect what now means? the idea was to give abstract ideas for basic algebra, calculus and some form of geometry. the best i can do for geometry is a personal bubble. idk I'm giving up so if anyone can clean these up or has any input that would be great thanks in advance. I forgot to mention that I decided to place this he…

If we consider the gravitational effect of the Solar system upon its nearest neighbours (or upon the gravitational field immediately outside it) does this change as the SS evolves with time? For example ,as Jupiter moves 180 degrees around the Sun is there a noticeable (or theoretical) effect on the gravitational field as experience by a body outside the SS? I ask this because I have heard that the effect of gravity is not dependent on the interior makeup of a massive body( the Solar System in this instance)

Yes ,I only had in mind what would be practical (and enlightening for me) Is there anywhere that these spacetime graphs have been written down? Some sort of a graphic spacetime depiction of the Solar system at some particular time (say t=01/01/2000 at midnight) If there was then we could make adjacent snapshots (eg t=24 48 ,72 hours later etc ) and run the snapshots like a movie. Accuracy not important ,just maybe as a way of looking at spacetime events in a non local way?

The existence of matter tells space how to curve, and curved space tells matter how to move. This is layman's terms to basic principle Behind Einstein's Genius thinking and is the heart of Relativity. Einstein's successfully linked for the first time, the phenomenon of gravity with that of spacetime and relativity. If mass exist anywhere in the Universe ,spacetime around it will curve. But depending on a few variables can affect how much. But if you take away the mass causing this Warped Spacetime, what causes the "Curved Fabric of Space" return to its previous state, into its unbent position?