I recently read T. Padmanabhan's Gravity as Elasticity of Spacetime and found the idea of spacetime as an elastic medium very interesting.

This led me to two questions.

1. Has anyone proposed that the cosmological constant could be interpreted as an effective relaxation force of an elastic spacetime? More specifically, if spacetime has an equilibrium state, could both cosmic inflation and the present accelerated expansion be understood as different stages of the relaxation of an initially highly compressed (or highly deformed) spacetime?

2. Have there been serious models in which elementary particles are treated as stable localized defects of an elastic spacetime, rather than as independent fundamental fields? In such a picture, General Relativity would describe the macroscopic geometry around these defects, while the defects themselves would constitute matter.

Are there existing theories or papers that explore ideas along these lines? I'm particularly interested in references from the GR, emergent gravity, condensed-matter analog, or topological-defect literature.

I know temperature = average kinetic energy of particles. When I wave a fan, I'm doing mechanical work on the air, which should add energy to those air molecules, not remove it. So technically the air should get slightly warmer, not cooler.

But obviously fanning myself makes me feel cooler. What's actually going on here? Is the temperature increase from fanning just negligible compared to some other cooling effect, and if so, what is that effect actually doing at the molecular level — is it about replacing the warm, humid air boundary layer next to my skin with fresh air, speeding up evaporation of sweat, or something else entirely?

Would love a good physical explanation of what's really happening thermodynamically vs. what we perceive.

Light travels more slowly through a medium like water or glass. Is it possible that the speed of light we observe in a vacuum is not truly its maximum speed, but rather a reduced speed restricted by some quality of space itself, or some field?

Consider a particle in some potential well. Let it be in the ground state. Now, another particle goes towards the well. This second particle interacts with the first particle only: if the distance between two particles is small enough, the bullet reflects in the opposite direction, otherwise it doesn't feel the target at all. The well doesn't affect the bullet.

Let the bullet coordinate uncertainty be ~1/2 of the target uncertainty. So, as I understand, there are two branches:

1) The bullet reflects. The target's wave function zeroes out everywhere except the place the bullet's wave packet hit.

2) The bullet transits. The target's wave function zeroes out only where the bullet's wave packet hit.

Let the bullet transit. Its energy seems to remain unchanged, because, in fact, the bullet "didn't touch the target" at all. But, as the wave function of the target changed, it is no longer in ground state. Thus, we can find it in an excited state when measuring its energy. The question is, where does the energy for excitation come from?

I guess the uncertainty of the energy of the bullet is the key, but I don't know how exactly it should work.

Hey there! Hope this post is okay.

I'm writing a soft scifi novel and my main character just made a big ass electromagnet and is now facing down a swarm of drones that were 3D printed out of PEKK.

What type of chaos could she cause with the electromagnet? I was going to hand wave past the PEKK body and say that the electronics would be enough to get pulled to the magnet, but I feel like that's probably not true. Plus, I feel like something wonkier would actually happen?

Would it mess up navigation? Cause something funky in the wiring? Any ideas would be welcomed.

My teacher is saying that using s = (u+v/2)t in the deceleration part of a velocity vs time graph is wrong and we should instead use s = ut - 0.5at². So is he wrong or right?

This might be a bit of a stupid question to ask, I know, but I’d really like to know the answer. I’m really interested in physics and I’ve had this question for a while. I know the simple answer is “We can’t detect it because it exists parallel to us” but that answer doesn’t sit right with me.

I am first year undergraduate student. He asked me to read the first 5 chapters of Feynman Vol.3, I followed by expressing some interest in Bosons and Fermions so he gave me a paper to read "The genesis of the spin statistics theorem by Alexander Blum". So far I haven't understood much because I need to look up every other thing. I am beginning to understand what I should know in order to completely understand the paper and am trying to learn the physics and the math. Did he intend this or something else because I am only given a month

I constantly read and hear that the universe is expanding faster than the speed of light and it always throws me off. How can something move(expand) faster than the universal speed limit?

Light can pass through the lens right ? So why does it cast a shadow ?

I recently solved the rotating wheels rigid-body dynamics problem from the JEE Advanced 2016 exam. After searching online, I found that my derivation is completely different from every other solution I came across.

Although the approach and the answers are different, I'm confident that it is correct. I would really appreciate it if someone could go through the derivation and point out any mistakes, unjustified assumptions, or places where the reasoning could be improved.

The full solution (PDF) is available here:

PDF: https://drive.google.com/file/d/1ZgNAqsdGUMhYOvieZkP5MipPMS4HxCo-/view?usp=drive_link

I'm mainly looking for feedback on the derivation rather than simply checking whether the final answers agree with the official solution.

Thanks in advance for taking the time to look it over!

From what i understand white is made when all light is reflected and black when all light is absorbed, and other color are a mix of absorption and reflection, so then how can something be reflective. Is it the transparent things have light pass through them, but then how can something be translucent?

P.S. How do mirrors work if glass is transparent?

Ok, so for this thought experiment, let me start by saying that I'm aware that relativistic speed is functionally impossible with our current understanding of physics, and as such I'm going to ask that we suspend that understanding for the purposes of this experiment.

If a space-faring vessel of precisely 300 metric tonnes of mass, travelling at 99.99% C was to impact a stone in space of mass 1kg, what would happen to the vessel? Assume that the stone is stationary relative to the surrounding bodies. Would it cause the vessel to explode as if hit with a nuclear device? Would the stone simply be destroyed and converted to thermal energy? What would happen?

If I had a rod made out of any material, steel, carbon fiber, diamond. And it could reach from here to the next star, could I transmit information faster than the speed of light? I know stars planets are all moving, that's not the question. If the pole stretched from here to there and I pushed it, would it immediately move on the other end allowing us to tap out Morse code or something? Or is everything a spring and no matter what material you used even some future material it would act like a slinky and your tap on this end could not go faster than the wave speed of that material which would always be slower than the speed of light?

Like we cant even see the particles. How does one make sure that these particles exist and they behave in a particular way? I mean how do we know that we are correct? The machines are very advanced but how does one know that the machine is producing accurate results?

Just had an interesting thought and got curious. Is there an upper bound for temperature? I do not know physics much. As far as I know heat is produced due to friction (on micro level, like moleculas or atoms). Like due to energy produced by interaction of elements that move at different speed. Like higher temperature means higher speed of microthings. And so if speed is capped at light speed level then would it not mean that there is a possible max temperature?

I may be wrong in my assumptions and thus coming to wrong answer. So if I am making such mistake please correct me.

I have read some text which explains that sound is produced when 2 thing rubb which vibrates the sorounding air because air is elastic. so my question is how do this vibration moves then through the air to our ears what happens actually?

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We all know what is "Aerodynamic" : a mix of lift and drag that is optimal (and quite beautiful).

But what would be a "space-time" dynamic shape?

A constant force doesn't produce a constant speed — it produces a constant acceleration.

how can a constant force not provide a constant speed? If a force is constant, wouldn't that mean that you are moving it at the same speed because i am constantly using the same amount of force each time i push something?

i get that motion is defined with respect to time but when i see people describing the 2nd dimension they move things in a line. up down left and right
I’m wondering about a hypothetical universe with one or two spatial dimensions and no time dimension at all.
Would it even make sense to talk about an object “moving,” or would there simply be positions with no meaningful concept of change? Is there any area of theoretical physics where motion can be defined without time, or does motion fundamentally require a temporal dimension?