Hello, everyone! I would like to ask you about more of a historical than purely physical. So, as far as I comprehended, according to a strict classification, every scientific theory intially should be regarded as a scientific hypothesis before it was proven via sets of experiments and accepted as currently right / working in circumstances it can be applied to. But I can't find any mention that Special or/and General Relativity theory had ever been regarded as hypothesis initially. Am I getting something wrong?

It's widely recognized that when light is trapped in a cavity, it creates standing waves and follows the rules of relativity. For instance:

In a moving frame of reference, the light bouncing back and forth in the cavity shows a change in wavelength, much like the de Broglie waves associated with particles.

These standing waves experience relativistic effects, such as length contraction and shifts in energy, which align with the principles of special relativity.

The image below demonstrates this phenomenon. The wavelength of the modulation envelope corresponds to an electron's de Broglie wavelength when the laser wavelength matches the electron's Compton wavelength.

Are there particular models in modern physics that explain this behavior in more detail? How does this relate to broader wave-based interpretations in quantum physics?

Hey guys,

So, I’ve been thinking about black holes a lot, and I came up with something that might be a solution to the information paradox. I’m 16, so I’m not a physicist or anything, but I’ve pieced this together using logic, and I really want to know if it actually holds up or if I’m missing something major.

Basically, my idea is this:

We know time dilation gets extreme near a black hole’s event horizon. From an outside perspective, anything falling in appears to slow down forever and never actually crosses the event horizon (because of infinite time dilation).

At the same time, Hawking radiation causes black holes to slowly evaporate over time.

If no object can actually reach the event horizon before the black hole evaporates (from our perspective), then nothing ever truly enters the black hole in finite time.

That means information isn’t lost—it’s just stuck in time, super redshifted, and basically undetectable.

So… wouldn’t this fix the information paradox? If nothing truly crosses the event horizon before the black hole disappears, there’s no paradox because no information is ever lost inside the singularity. It’s all still “there,” just impossibly stretched in time.

Does this idea make any sense? I feel like it’s too simple to be right, but at the same time, I can’t find the flaw in it. Has something like this already been proposed? I’d really love to hear what people who know more about this think!

Hi everybody, I've been studying calculus and physics for about 5 years now (I'm in 9th grade btw) and there's still a lot I don't know. Now I do know the basics such as poly integrals, or limits and derivatives, and there are more specific ones l've been studying such as Fourier complex integration and cooling convection concepts or gamma functions and sigma notation.

But there was one concept that always seemed to stump me no matter how much I studied, Trigonometry, more specifically sin and cos in U-substitution, l've tried to understand stand it by watching examples and videos but it never quite stuck with me. I don't understand how but I know that it uses Pythagorean theorem which is A squared plus B squared equals C squared but as far as SOH CAH TOA I just don't understand it. Can anybody help me?

So there is no scientific proof of objective flow of time and it can be just psychological construct?

Some citations from books:

Brian Greene – The Fabric of the Cosmos (2004):

"All moments—past, present, and future—equally exist. Just as every location in space exists whether or not we are there, every moment in time exists whether or not we are experiencing it. The passage of time is a psychological construct*, not something fundamental to the structure of the universe."*

Sean Carroll – From Eternity to Here (2010):

"The passage of time is a feature of how we perceive reality, not of reality itself. The laws of physics describe a universe where time is just another coordinate, and it is only our experience as observers that makes it seem to 'flow' from past to future."

Vesselin Petkov – Relativity and the Nature of Spacetime (2005):

"If the world were objectively three-dimensional, the present moment would be uniquely real, and the flow of time would be an inherent feature of reality. However, relativity suggests that past, present, and future all coexist, making the flow of time an illusion of human consciousness*."*

Hello! I work at CERN and am planning to apply for US grad programs for the Fall '26 intake. My current projects (separately) deal with (i) HEP phenomenology of jet physics in lepton colliders, and (ii) incoherent effects in hadron beams of the LHC. I know these are quite distinct topics, but I am continuing to work on both until I feel confident about choosing one avenue over the other to continue pursuing for the PhD.

So far I have looked at the bigger names linked with national labs (Stanford-SLAC, U.Chicago-FNL/ANL, UCB-LLNL, etc). However, I would like to know other decent schools specialising in accelerator physics. Any input would be of great help. Thank you :)

Assuming the Block Universe theory holds true, and past, present, and future are simultaneous. Is the MWI concept of measurements creating branching universes be conceptually inaccurate? Is it just as reasonable to state all variations exist simultaneously or instantaneously? Further, would the divisions in probabilities be comparable to divisions of past, present, and future? To describe this poorly, can the universal wave function be a block?

What is the probability of a halo around the MW that creates quantized particles of space. The particles created are pushed away from the halo to participate as members of intragalactic and extragalactic space.

Intragalactic particles will move to replace particles consumed by matter, along the way they will help to create and maintain the galactic rotation curve.

Extragalactic particles will join as new members and contribute their share to an ever expanding Universe.

Thank you for your time and patience.

I was recently surprised to learn that steel and aluminum balls placed fairly close to a nuclear bomb can survive the blast. In 1955 during Operation Teapot, several of these balls with a diameter of 10 inches were placed at distances ranging from 13 to 400 feet away from a 23 kt fission bomb. Of these, only the ones on the floor of the shot cab 13 feet away from the bomb weren't recovered. The rest, including ones just 80 feet from the bomb, survived with various degrees of damage. Another similar test I read about was one where a 30-cm steel ball coated in graphite survived just 9 meters from a 15 kt bomb losing only 0.1 mm of its radius, although I couldn't find as much information about this test. With this in mind, is there a certain distance at which no material can survive a nuclear bomb (excluding things like neutronium which can only exist under extreme gravity)? How does that distance change with yield/weapon design? Would a fusion bomb have an easier time vaporizing things than a fission bomb of the same yield? Thanks for any responses.

Can you please provide with few basics on the Wimshurst machine. Cause I am trying to give it as a gift , however I never actually owned the machine myself and only used it for 15 seconds at school. So the questions are:

1. What are the actual safety rules that I had to give to the recepient of said gift? (other than common sense?). for example is it too unsafe to build up charge and leave the device without discharging, can it actually be hazardous?

2. Is it ok to put some small stickers on it? Obviously they won;t be placed on the metal strips or discharge spheres,, but what about plastic parts or the outside of Leyden jars? Or are stickers absolutely should not be placed anywhere on this device?

In a ton of scifi books and media set in the future, the characters scoff at electronic technology as being hopelessly outdated, "an electronic table, do you need a chisel to work it." Then they go on to give out some technobabble about using a "positronic computer" or a ship operating on "graviton power" or something like that.

Is that even possible? Is there some means of producing something that could do everything that electricity does, both in terms of providing usable energy for so many applications operating switches for computing?

We do know it takes about 8 minutes and 20 seconds for the Sunlight to reach to Earth. That is something I accept, and does make sense. However, since light is a wave, and it travels across space to reach us, and that energy takes about that amount of time. However, if you are using a telescope, and looking straight at the sun (with filter on of course knowing how dangerous it is), are you technically bypassing all that energy and looking at the Sun as it is currently, and not what it appears to us 8 minutes and 20 seconds ago?

Let’s take it further. We have the one of the most advanced Telescopes, the James Webb Telescope, and we use it to peer into the past, and seeing the galaxies that are beyond 10+ billion years old. IF we are to zoom into one of the galaxy, and look in one of the stars there (assuming it’s advanced enough), are we looking into the star in real time, or does that look like that 10+ billion years ago, if I am making sense?

Let’s look at this article for an example: https://www.eso.org/public/news/eso2417/

Here, astronomers are able to see a star outside of the galaxy, that is 160,000 light years away away from us. Does it mean we are seeing this star 160,000 years ago, or is the telescope actually bypassing all that waves and seeing the star as it was when the article was published?

Please let me know if this is the right place to ask. I know it may sound all theoretical but I would like to hear the physics aspect behind this.

If the question sounds odd, it did to me too. I have seen two different people, who each operate their own decently popular physics YouTube channels, make the claim that a time dilation gradient like you would expect to see in a planet's gravity well (time is more dilated the closer you get to the planet) actually emerges as a result of an object being in an accelerated state (including, but not limited to, standing on the surface of said planet), and that this emergent time dilation gradient would disappear to the object once the object is in free fall. This was given as an argument to why time dilation can't "cause" gravitational attraction.

The concept is so foreign to my understanding that it's caused me some distress. Is this a real concept in relativity, or resemble one in any way? Surely it had to have come from somewhere.

So I'm doing a project with a mentor where we modelled a Schwarzschild black hole using Lagrangian mechanics and Python. Essentially we used the Schwarzschild metric, considered the schwarzschidl radius to be 0 and the second angle theta to be constantly 90 degrees, so d-theta = 0. Anyways we then used this and divided it by dtau^2, with tau being the proper time of the particle orbiting the black hole, to get the Lagrangian, which we plugged into the euler-lagrange equation and then used python and stuff.

What lost me in the process was why we divded the schwarzschild metric (presented in the form ds^2 = something) by dtau^2 to get the lagrangian. I then realised I don't really understand what the Lagrangian actually represents, as in most examples I've tried my hand at (double pendulum, elastic pendulum, body on a slope), it was always the kinetic energy minus the potential energy, but in this case we did not do that and instead derived it using some random derivation which I do not understand.

Since I am writing a Maths IB IA on something similar, I need to put in a definition of a lagrangian that fits the method I am using, but I also want to understand it before just copy-pasting, so I guess my final question is just what exactly is a lagrangian and why did we use this derivation for the lagrangian in my case?

Edit: I'm probably gonna need a simplified answer because I'm still a high school student so ELI5

Question related to Cosmology.

Edit: I found out through comments, that I made some mistakes while writing this and left some details. I have expresssed my thoughts in a bit more detail in the comments. Please read that. The following things makes no sense.

Let's define timespeed as the rate at which time moves in spacetime. We don't assume its value yet.

There are three possibilities:

1. Timespeed > c → This is impossible because nothing can travel faster than light.
2. Timespeed < c → This would mean that an object at rest moves slower than time. If that were true, a body moving at a speed lower than c−timespeedc - \text{timespeed}c−timespeed wouldn't experience time dilation because it wouldn’t be approaching the speed of light. But we know that any motion, no matter how small, causes time dilation, meaning spacetime bends even for tiny velocities. This contradicts the assumption that timespeed is less than ccc.
3. Timespeed = c → Since we've ruled out the other two cases, this must be the correct one.

This means that even an object at rest is always moving through time at the speed of light. When it gains velocity, some of its motion shifts from time to space, causing time to slow down—exactly as relativity predicts.

Does this reasoning check out?

*Note the prompt I used is AI generated because my original prompt was way to gramatically incorrect and also that i didn't know if anyone would understand it. Other than that I completely thought of this on my own. If this was already a thing however I am sorry for claiming it to be mine. I am not that into physics but I just wanted to see if what I understood is correct or not.)

If you have two object of mass m=1kg moving away from one another at speed = 10m/s relative to the midpoint between two object, then total KE of the system is

KE1 + KE2 = 0.5110^2 + 0.5110^2

KEtotal = 100J

But if we measure from the frame of reference of object 1 then total KE becomes

KE1 + KE2 = 0.510^2 + 0.5120^2

KEtotal = 200J

But this seems wrong, so I think I'm missing something about how Kinetic Energy is handled in different relative frame of reference

Or is the earth so large that we haven't made much of an impact on this protective barrier?

I'm going to need a bit of an ELI15 on this. Magnets and electromagnetism have always been difficult concepts for me to understand. I'm 50 and grew up in a small town. Our particular education system wasn't that great with the sciences.

If a body gives off the energy L in the form of radiation, its mass diminishes by L/c^(2).

https://www.fourmilab.ch/etexts/einstein/E_mc2/e_mc2.pdf from Einstein paper 1905.

ΔE = Δmc^(2) (L is the change in energy) So this would imply that
E = mc^(2) + some constant K ( K is constant for a given object) Isn't this kind of the same thing as lambda in general relativity? How does K become zero? I understand that for a particle which is its own anti particle (photon, Z boson etc) K has to be zero, But for a particle which is not its own antiparticle, wouldn't all equations work if the particle say electron had E = mc2 + 10kev and positron had E = mc2 -10kev Is there something that explicitly forces K to be zero even for particles that are not their own anti particles? Was there any experiment actually done to measure the difference in gravity of a particle and anti-particle? (like the vacuum drop cannon ball and feather)

I'm familiar with how sine waves arise from system where acceleration is dependent on position, like a spring, but aside from the math, I don't have an intuitive understanding of why.

Does it have to do with the principle of least action? What quantity or value is at a minimum in a sine wave, relative to a square wave or triangle wave?

Maybe a sine wave is the lowest energy way to oscillate between two values and nature is just lazy?

Hey I am starting Calculus based Physics but honestly I suck at calculus and it’s too late to switch to non calculus based physics, what fundamentals from calculus do I need to study up on for just Physics 1?

This has been haunting me for a while. Last October I was at a music in the park concert with my family. Everything was great, we were listening to the live band and all the sudden the band slowed down (I thought they were stopping in the middle of the song) and then sped back up to the natural time speed. My wife saw it too, and we both just looked at each other. “What was that?” She saw it and I saw it. It was like time was being controlled with a knob and someone slowed it down then brought it back up. She happened to be recording on her phone. We rewatched the video and you can definitely see a blip where the time slowed down… but the blip was nothing like what we experienced in person.

Any ideas on what happened to us

If the atoms in a grain of rice are aranged side by side like a long rope, how long would it span?

Python program at the end
We know that General Relativity, while brilliant, is incomplete, just look at our neighbor, Andromeda. We simply cannot reconcile its rotation curves without invoking dark matter, which remains nothing more than an indirect necessity; we have zero direct evidence for it. All we see is extra gravity, yet no additional mass is lurking around.

What we need is a model of gravity that aligns with GR’s predictions at the black hole’s edge, where we have strong empirical support, but then naturally evolves from there such that. At the event horizon, gravity must drop off as GR tells us it does. Then, as you move away from the black hole, gravity should begin to increase, providing the extra pull we observe in galaxies (dark matter), before finally decreasing at larger, cosmic scales. And this entire behavior must come from first principles, with no fudging or arbitrary adjustments.

Such a model would not only predict the velocities of objects at the edge of Andromeda, explaining why the rotation velocity remains flat instead of decreasing, but it would also account for the additional gravitational effects without resorting to unseen dark matter. Even more, if the emanation of space can explain cosmic expansion, it could also offer insights into dark energy. This isn’t just speculative; it’s an organic result of a theory that smoothly transitions from the strong field regime at black hole surfaces to the weak field, large scale structure of the universe.

The key twist is that every step of this gravitational dance is modulated by the space emanation Q = 4 * math.pi * R_0**(3/2) * math.sqrt((2 * G * Mass) / (1 - (2 * G * Mass) / (R_0 * c**2))) which is the protagonist of the model, and time dilation factor 1/ math.sqrt{1-2GM/(Rc^2)} , It’s what causes transition: near the event horizon, where time nearly grinds to a halt, this factor tames the gravitational pull, making it much lower than you would expect. As you move away and time recovers its normal pace, the dilation effect fades, allowing gravity to ramp up and even mimic the extra pull we see in galaxies, before falling off. Time dilation and space emanation are the silent orchestrators behind the scene, ensuring that gravity evolves smoothly from the extreme conditions at the horizon to the gravity observe on cosmic scales, all without any arbitrary tweaking.So you get the expansion(dark energy), through space emanation and from there you calculate g, which then in turn gives you (dark matter) extra gravity.

Run the program using spyder, play around. Check, the results. Get familiar with the model because this is what they it will be teach in Schools in the future. This model also work for calculation in non extreme enviroments and matches GR known predictions.

import math

# Constants

G = 6.67430e-11 #gravitational constant

c = 299792458 #speed of light

Mass_Black_Hole = 2.7e40 #Super Massive Black Hole, Andromeda, M 31

Rs= (2*G*Mass_Black_Hole)/c**2

print("")

print(Rs, "Schwarzschild radius")

altitude = 11900

Mass= Mass_Black_Hole

R = 40101265453240.80

h = R + altitude

h2= R + 1000000000

h3= R + 1e18

h4= R + 1e25

correction_factor_GR = math.sqrt(1 - (Rs / h))

correction_factor_GR2 = math.sqrt(1 - (Rs / R))

correction_factor_GR3 = math.sqrt(1 - (Rs / h2))

correction_factor_GR4 = math.sqrt(1 - (Rs / h3))

correction_factor_GR5 = math.sqrt(1 - (Rs / h4))

# SET Volume Function (Q)

Q = 4 * math.pi * R**(3/2) * math.sqrt((2 * G * Mass) / (1 - (2 * G * Mass) / (R * c**2)))

print("")

print(Q, "Q MASTER FORMULA, total emanation from Black hole")

print("")

print("----------------------------------------------------------")

print("Gravitational acceleration GR, SET, NEWTON at the surface of Black hole")

print("----------------------------------------------------------")

g_GR = (G * Mass) / (R**2 * correction_factor_GR2)

print(g_GR, "gravitational acceleration General Relativity ")

k = (c**3) / (4*G*Mass)

print(k, "gravitational acc, using surface gravity c^3 /4GM, Schwarzschild Black Hole Relativity ")

print("")

g_SET = (Q**2 * (1 - (2*G*Mass)/( R * c**2 ))/ (32 * math.pi**2 * R**5))

print(g_SET, "gravitational acceleration SET ")

print("")

g_newton = G * Mass / R**2

print(g_newton, "gravitational acceleration Newton,")

print("")

print("--------------------------------------------------------")

print("Gravitational Acceleration GR, SET, NEWTON at altitude 11900 meters from surface ")

print("--------------------------------------------------------")

print("")

g_GR = (G * Mass) / (h**2 * correction_factor_GR)

print(g_GR, "gravitational acceleration General Relativity ")

print("")

g_SET = (Q**2 * (1 - (2*G*Mass)/( h * c**2 ))) / (32 * math.pi**2 * R**3 * h**2)

print(g_SET, "gravitational acceleration SET matches GR at edge of Black hole")

print("")

g_newton = G * Mass / h**2

print(g_newton, "g Newton,")

print("")

print("")

print("--------------------------------------------------------")

print("Gravitational Acceleration GR, SET, NEWTON at altitude 1 billion meters from surface BH, g increases ")

print("as observe in dark matter models")

print("--------------------------------------------------------")

print("")

g_GR = (G * Mass) / (h2**2 * correction_factor_GR3)

print(g_GR, "gravitational acceleration General Relativity ")

print("")

g_SET = (Q**2 * (1 - (2*G*Mass)/( h2 * c**2 ))) / (32 * math.pi**2 * R**3 * h2**2)

print(g_SET, "gravitational acceleration SET increases as you move from BH due to Time dilation decrease")

print("")

g_newton = G * Mass / h3**2

print(g_newton, "g Newton,")

print("")

print("")

print("--------------------------------------------------------")

print("Gravitational Acceleration GR, SET, NEWTON at altitude 1e18 meters from surface BH, g starts to decrease ")

print("--------------------------------------------------------")

print("")

g_GR = (G * Mass) / (h3**2 * correction_factor_GR4)

print(g_GR, "gravitational acceleration General Relativity ")

print("")

g_SET = (Q**2 * (1 - (2*G*Mass)/( h3 * c**2 ))) / (32 * math.pi**2 * R**3 * h3**2)

print(g_SET, "gravitational acceleration SET increases as you move from BH due to Time dilation decrease")

print("")

g_newton = G * Mass / h3**2

print(g_newton, "g Newton,")

print("")

print("")

print("--------------------------------------------------------")

print("Gravitational Acceleration GR, SET, NEWTON at altitude 1e25 meters from surface BH, g decreases further ")

print("--------------------------------------------------------")

print("")

g_GR = (G * Mass) / (h4**2 * correction_factor_GR5)

print(g_GR, "gravitational acceleration General Relativity ")

print("")

g_SET = (Q**2 * (1 - (2*G*Mass)/( h4 * c**2 ))) / (32 * math.pi**2 * R**3 * h4**2)

print(g_SET, "gravitational acceleration SET increases as you move from BH due to Time dilation decrease")

print("")

g_newton = G * Mass / h4**2

print(g_newton, "g Newton,")

print("")

sqrt_term = 1 - (2 * G * Mass) / (R * c**2)

if sqrt_term < 0:

raise ValueError("Error: sqrt term is negative, increase R!")

escape_velocity_formula_Q = (Q * math.sqrt(sqrt_term)) / (4 * math.pi * R**2)

print(escape_velocity_formula_Q, "escape velocity SET formula")

When we observe the energy of quarks to experimentally determine their rest masses we find that they have very high energy and travel near C. But are we sure that these observations are not the result of the energy put into the protons/neutrons by smashing them together at high speeds, thus we are really looking at their relativistic energies? How are we sure that we’ve corrected for this?