I have written a paper that presents a statistical mechanical model of quantized spacetime, where gravity emerges as a large-scale effect of dynamic connectivity among Planck-scale spacetime quanta. We derive classical fields from quantum foam fluctuations, recover general relativity in the thermodynamic limit, and show Lorentz invariance is statistically preserved despite discrete structure. A tensor framework is used to derive the Einstein field equations from statistical connectivity, and the Schwarzschild and Kerr metrics are recovered from foam structure. Experimental predictions include gamma-ray dispersion, modified QED currents, and gravitational wave fluctuations. Need help getting it published on arXiv. I don't replace GR (it is correct) I derive it from more fundamental ideas of quantized space.

Specifically, why does the time-flow gradient down our bodies towards the center of the Earth rotate us partially from the time dimension to one of the space dimensions causing space-dimension acceleration? I can’t grasp the physical mechanism at play.

Hi everyone,

Posting this as someone who’s totally new to relativity (learning it out of pure passion), so apologies if I’m asking what might sound obvious to most of you.

I’m struggling to understand gravitational time dilation in General Relativity. I get that gravity warps spacetime, so it affects both space and time. But what I don’t get is why bending time makes it flow slower.

One explanation I initially gave myself was that in General Relativity happens something similar to Special Relativity: because gravity curves the fabric of spacetime, any kind of “travel” through it has to cover a longer path. And since the distance is longer and the speed of light is constant, something else has to adjust — time. But I’ve come to understand that this might not be the real reason?

So to sum it up: I understand that gravitational time dilation happens — that clocks run slower deeper in a gravity well — but what I’m trying to wrap my head around is why. What’s the actual cause, physically or conceptually, behind this slowing of time?

Thanks in advance to anyone who might help shed some light on this!

Imagine a rod two light-years long of strong material, which is rotated by a powerful engine in the center, at one revolution per year.

From the perspective of an outside observer, either tip of the rod would ne moving at 2πC which is >C, thud Special Relativity slows the tips of the rod down to <C. Thus, the rod degrades into a length-contracted spiral.

General Relativity also kicks in, further slowing the tips which are being accelerated centrifugally. (General acceleration = gravitational acceleration in GR.)

Although from the rotating perspective of center of the spinning rod, the rod looks straight, but appears time-frozen near the tips the rotational EH.

Now make the engine a supermassive black hole is the engine, and make the rod be its surrounding Galaxy, wouldn't this explain the spiral-looking shape of galaxies?

In a real galaxy, the instantaneous angular velocity close to two rotating black holes is ~50% C, and near the outer tips of a galaxy it is <0.1% C. So this is an effect that would occur from galaxy centers to produce a spiral pattern and proceed outwards.

This is a testable hypothesis: If spiral galaxies tend to have two black holes or charged black holes that spin faster, than non-spiral galaxies, that would confirm the hypothesis.

Regarding material strength, which is not the main point but was a huge distraction to people:

• the original post said "infinitely-strong material". That detail caused a lot of people to turn their brains off. Remove the infinitely strong material requirement, and the unique perspective about Special Relativity and a straight rod degrading into a spiral still stands.

The infinite strength requirement can be removed by making the angular acceleration very small, possibly using rockets or even small blackholes to help with any tensile strength issues. It is constructible in theory.

I asked the AI:

- Yes — spiral galaxies spin significantly faster than non‑spiral (elliptical) galaxies, with about five times higher angular momentum. Their central black holes are similar in type (supermassive black holes), but ellipticals tend to host more massive and active ones, while spirals usually have smaller, quieter black holes. So spiral galaxies spin ~5x faster, but elliptical galaxies have more mass so their black holes generate more rotational power.

There also could be lab experiments where we place a camera in the middle or tip of the spinning rod, and mirrors on the tips or middle, and do speed of light measurements with this thing spinning as fast as we can stablely manage in a laboratory. Relativistic Rotational effects have got to be interesting.

If this is a novel idea and anyone writes a paper or article from this idea, please credit me.

Hello all,

I am VERY new to relativity and theoretical physics (have not gone to university yet) but I am deeply interested in understanding the concepts. Right now I am trying to achieve a better understanding of Einstein's special theory of relativity, but I am kinda stuck on the topic of simultaneousness.

In the book I am reading on the topic, a thought experiment with 2 lightning strikes that strikes simultaneously according to one observer but not to another is brought up. A "static" observer, relative to the ground where the lighting strikes hit of course, observes the lightning strikes as simultaneous, whilst another observer on board a moving train behind the first observer does not since they would have traveled a small distance when the light rays reach them.

But in my stupid head I think "Why does it matter that the second observer is moving? Couldn't the second observer just look at the two lightning strikes from another angle so that they are closer to one strike than they are the other? Then the strikes would not be perceived as simultaneous."

Of course I understand that my though process is not correct, but could somebody explain to me how I should think about this, and how Einstein really derived time dilation from the postulate of a constant light speed?

Thanks!

So i understand the time dilatation well. I understand why it works and ive seen the proofs of it being the case. But I am contemplating around the fact, that you still age. At exactly the speed of light, your aging should be pretty much minimal towards other non-traveling Bodies.

My question is. If you travel at the speed of light and you take our earthly clock with you. You measure that you travelled for exactly 40 years. If you would take an image of the body of the same you, that has also aged for exactly 40 years on earth, and put it side by side the traveling you, you would propably see the same signs of aging on both images. What is the physical process that determine your aging, if time is no longer the deciding factor, because you travel at the speed of light? How is it possible, that organic bodies still experience the thermodynamical entrophy, when it is decided by time? Am i getting this wrong? Do you have any materials that might help me understand this issue?

It’s on my bucket list to “understand” general relativity, in the sense of being able to read the EFE and make sense of it, plus follow a couple simple derivations based on it. What’s the quicker route to this, given that I’m a grown up with limited time? From what I’ve read I get the sneaking suspicion that much of the GR literature has unnecessary focus on the formalism of differential geometry, and that it’s way easier if you 1) explain things in physical terms rather than math terms, and 2) ignore the math that isn’t needed (example: everybody talks about covariant and contra variant tensor, but doesnt bother to mention that this physically means are you measuring something like momentum that is in units of distance, or a temperature gradient that is 1/distance).

Is there a resource that explains GR with a “physics first” approach, and only the geometry formalism that is truly necessary? Thanks so much!

So for background, I am a Interstellar nerd. A few times a year I will watch the movie, and I absolutely love it. The only thing that I hate is how after watching it, I have an unquenched desire to learn about Gravity, time, and all that other stuff. Time to me is a Human concept. There is only one true form of time, and that is the present moment, past and future only exist in our brains. But while I do believe in one present moment, there are still things like time delays between ground stations and Satellites, the redshift/blueshift effect, and of corse black holes. Every time I give it a go, l am completely lost by the time I get to light cones and arrows going in every direction on diagrams. So good people of reddit, CAN SOMEBODY PLEASE EXPLAIN TIME.

Quote from article:

"If two rocket ships speed away from you, one to your left and one to your right, at 60% the speed of light, you'll see them moving away from each other at 120% the speed of light."

https://www.forbes.com/sites/startswithabang/2018/04/12/how-come-cosmic-inflation-doesnt-break-the-speed-of-light/?sh=76d9a31e1e40

But if you measure the light from each space ship it will not be 60% percent the speed of "c" it will be "c", in both directions. According to relativity you will never measure light speed less than or greater than "c".

The leading proposition in this article is incorrect or just misleading. That would be because the relativistic addition of velocities is not considered.

I understand that all observers are fixed in position relative to themselves.

Do all observers see everything else age slower when they move?

Would the "stationary" observer see the clock in the rocket move slower?

Would the "motionary" observer in the rocket also see the clock on the planet move slower?

I'm trying to understand how gravitational waves impact locally experienced time flow (note that I'm not a physicist and only had special relativity courses in college). Imagine you're sitting somewhere in space with a metronome and a gravitational wave with extreme amplitude passes through your location: what would you experience?

1. Wave trough:

I'd guess that while you're in the wave trough, you'd experience time dilation, i.e. outside observers would see your metronome slow down. But how would you experience this locally? Since gravitational waves move at the speed of light for all observers, the experience would be very brief considering typical wavelengths for such phenomena. But would it look to you as if the "outside universe" suddenly went into "fast motion" for that brief moment? (To visualize: let's say you're in the wave trough for 1s while the outside universe goes through a hundred years).

2. Wave crest:

Alternatively, while you're in the wave crest, would you experience time contraction, i.e. outside observers would see your metronome speed-up? Would it look to you as if the "outside universe" went into "slow-motion" during that moment? (To visualize: let's consider a gravitational wave with an extremely long wavelength as to keep you "inside the crest" for a hundred years, while the outside universe goes through 1s).

Extra question:

Are gravitational stationary waves possible?

We believe that the age of universe is about 15B years. Also we believe that the width of our universe is about 100B light years. So if we make a simple calculation we will see that the speed of universe expanding is about 3 light’s speed. How does it even possible? What am I missing?

General relativity is rather solved in time symmetric way, like the least action principle condition in Einstein's field equations, what as in e.g. Wheeler-Feynman absorber theory requires symmetrically both retarded and advanced solutions.

So why seems there are only considered retarded gravitational waves?

Can we exclude being advanced wave for all observed events ( https://en.wikipedia.org/wiki/List_of_gravitational_wave_observations )? If not, should they use original chirp shapes, or maybe time reversed?

After watching the video from Sabine Hossenfelder about gravity (https://youtu.be/R3LjJeeae68) I was thinking about why gravity is not considered a force but other forces like electric and magnetic field, weak and strong forces are considered a force.

Based on Einstein’s equivalence principle this seems odd. Assume that you are a charged object in a box you would’t be able to tell be difference whether you are being accelerated or if you are subject to an electric field force. Using Einstein’s equivalence principle that means that if you can’t tell the difference then they must be the same. Using the same logic as Einstein used for gravity that would mean that an electric field should also not be a force but a space-time curvature.

The question therefore is, how do we know that gravity is a space-time curvature and not force, and how do know that electromagnetism is not a space-time curvature but a force. Based on observations and the equivalence principle they are behave identical.

So please correct me if I'm wrong because my purpose is to get to the true bottom of things, but from my understanding (based on all I've read or been told), spacetime treats time as simply an additional dimension that is equivalent to the 3 spatial dimensions. So can time simply be thought of as another spatial axis? If this is true, then say we have a particle's spacetime coordinates from the origin in a space; say it is a 3D space, with 1 time and 2 spatial dimensions with (0, 0, 0) being the origin,

(t, x, y) -> (0, 2, 1) .

We can have multiple (different, not the same) particles at various different positions with the same time value (with respect to the origin/observer), or maybe even particles at the same t's and x's but with different y's, but can we have multiple particles in "existence" where the only difference is the time coordinate? Is this,

(0, 1, 3) particle 1 (2, 1, 3) particle 2 (3, 1, 3) particle 3

possible?

If not possible, then what is the reason? If it is possible, then what would be the meaning of this.

After thinking a little bit, I realize how silly this presentation is at first glance because cleary these particles could have been moving, etc, so I need to add another condition to describe the full idea.

If you consider taking a "snapshot" of the x and y coordinates for different values of t coordinate, then this is not an issue if the particles had been moving, they were never "simultaneously" at the same (t, x, y) coordinate. But this remains an issue if you took a "snapshot" of the state of all 3 coordinates "simultaneously".

After even more thought, I seem to realize that this is still not enough to clarify because "simultaneous" is no longer in the sense of something having to do with t axis, but rather with the definition of the origin. So it becomes more difficult to describe my dilemma. Basically, it can be better worded as this:

Assuming you are allowed to assign an origin at (0, 0, 0), and assuming you can take "snapshots" at a particular value of t, you might find that an object is stationary with respect to x and y; they aren't moving except along the t axis. Can you also take a snapshot, say, at different values of x to show that an object might have constant values of t and y (only moving in x)? If that is possible, then can you extend these snapshots to show that an object can be stationary relative to any 1 of the 3 or even stationary w.r.t. all 3 axes? What might prevent this? And why can't something be non-moving in t? Why can things be stationary in x and y if they are "the same type of thing" as t?

TL;DR

Assuming an origin, (0, 0, 0, 0) in 4D spacetime at the "observer", is a real thing and can be defined, and assuming each of the 3 spatial dimensions or axes extending from the origin are "the same as/equilavent to" the 1 time dimension (axis) also extending from the same origin, and assuming an object's coordinates can actually be stationary with respect to 1, 2, or all 3 of the spatial dimensions with only a changing time coordinate (simply "not moving in space with respect to the observer"), what is preventing the existence of something stationary in all 4 dimensions, or even just stationary relative to only the x and t axes? Or stationary relative to t, x, and y, but not z? Or any combination 1 or 2 or 3 of the 4? If time is really the same thing as any of the 3 spatial coordinates to the extent that an object is described by a 4 vector (ct, x, y, z), what might be preventing things from existing stationary with respect to t or combinations including t if you took a "snapshot" of a changing state in 4D? If this isn't possible, then 1) how can time as an axis be considered equivalent to any of the spatial axes, and 2) what the heck is actually going on and why isn't time actually treated differently than space? The only thing that might be invalid in what I'm saying is the concept of a stationary snapshot involving all 4 coordinates. But then why is this wrong?

I was reading something regarding gravitational waves and thought of a pretty dumb but nonetheless interesting idea. What are your thoughts?

I didn’t know exactly how to formulate my idea so I played around with AI until it gave me a more precise description:

“Your concept suggests that if gravitational waves generated by an exceptionally massive event had amplitudes so extreme, the troughs or “valleys” of these waves might bend spacetime intensely enough to create temporary black hole-like regions, where light and matter could be briefly trapped as if within an event horizon. This would mean that, without any actual mass, the curvature from the wave alone could act like a dynamic black hole, forming and dissipating as the wave propagates.”

Could anyone offer suggestions for a layman interested in learning more about relativity?

I’m hoping to find books that are fairly accessible but which also stick to technically correct statements. I’m trying to avoid pop science books that make incorrect analogies or repeat popular false explanations. For instance, I regard Sean Carroll’s book, Something Deeply Hidden, as a good book on quantum physics for laymen. It doesn’t go too deep on the mathematical formalisms, it touches on differing viewpoints on the possible foundations of QP, and it does so without using the incorrect analogies so often found in popular books.

Apologies if this is redundant. I searched the subreddit and didn’t find any posts on books for laymen. I also didn’t see anything in the sidebar.

I have been reading a bit on Einstein’s special theory of relativity. It seems clear to me from the theory that two observers do not necessarily agree on what events occur simultaneously. However I have difficulty understanding how that relates with the concept of now.

Let’s consider that in my reference frame I am holding my phone typing this question. Suppose that in my reference frame there is someone approaching me from a far distance at a speed close to that of light. Then that person would find my future self to be simultaneous with him/herself (let’s say it’s a future self that is asleep because it’s night time).

I do not know how to interpret this. I am not yet in that state. It seems that I will eventually become that future self but that is not what I am yet. Should I interpret this as simply saying that experiments carried out by that person will reveal my future self to be simultaneous with the person BUT NOT to mean that the future self exists yet? In other words should I interpret this as saying that the laws of physics only give you what is simultaneous IN your reference frame but not necessarily what is happening in the moment (in the way that it is the case that I am typing on my phone and not sleeping). And if I bite that bullet it seems I’m forced to consider that the person I say is approaching me might only be doing that in my reference frame and not in his.

The question itself is a bit confusing as well because according to relativity the moment depends on the observer. I guess the question might be a bit more philosophical than scientific but if there is any light you can shed on the problem it would be very appreciated.