r/AskPhysics 3h ago

If you fall into a black hole, how much time in the outside universe can you watch go by. If you orbit close to a black hole can you watch all history go by?

3 Upvotes

Title


r/AskPhysics 21h ago

Any physics majors/physicists that read philosophy in their spare time

68 Upvotes

Hey just wondering if any physics students or physicists read philosophy as interest . And not necessarily just philosophy of science. But other fields of philosophy such as metaphysics, existentialism, logic. And even maybe some literature classics. After a long uni day full of physics I know a good literature classics helps my mind truly relax.


r/AskPhysics 5h ago

LUX-ZEPLIN possible WIMP detection

2 Upvotes

Saw articles and read the preprint on the potential detection of a single WIMP likely have a mass of at least 200 GeV/c2. I understand this does not reach statistical significance and may be ruled out but am curious of peoples thoughts on this as the paper is impenetrable for me to fully understand although I understand the overall effort to exclude background and other events. My question is does the results just tell us a potential large particle as noted or did the experiment tell us anything beyond that.

In my effort to find something I can understand I went to Wikipedia on the effort and read this:

" Although future analysis is required to confirm or refute the event as a genuine dark matter detection—the event's statistical significance does not clear the 5σ threshold of a "discovery" in particle physics—the event's high recoil energy is consistent with weakly interacting massive particle (WIMP) models in which WIMPs have either different internal energy states or couplings with ordinary matter that vary with momentum.\23])\24])" My question is what is meant by WIMPS having different internal energy states of couplings with ordinary matter that vary with momentum. Additionally in the preprint itself they say at the end of the abstract "We describe the analysis and event of interest, the background model used in the statistical inference, and detail several of the rare background topologies considered." Does rare background topologies refer to ruling about background or are they talking in regard to potential properties of the signal?

I guess at the root of my question for this preliminary finding did they just find a potential signal of a particle at least 200 GeV/c2 or were there other things that tell us more beyond this. The paper is too complicated for me to know if there is more information beyond that not understanding all the terms. What do you experts think? Thanks. Here is the preprint for reference:

https://lz.lbl.gov/wp-content/uploads/sites/6/2026/08/LZ_Preprint_260901_Dark_Matter_EFT_Nuclear_Recoil_Search_at_Higher_Energies.pdf


r/AskPhysics 2h ago

If entropy is a method for determining “Time” does hawking radiation prove time displacement in a meaningful way?

0 Upvotes

If we have a baseline for how thermodynamic reactions SHOULD OCCUR…

And yet Blackholes radiate at 1 trillionth of a kelvin..

We could extrapolate backward from that, and say “Given this mass this is what we WOULD EXPECT to see”

So by measuring the low intensity of hawking radiation do we use this to confirm “Yes time is definitely running slower inside the black hole because of this relationship of energy out, vs what should be happening inside if time were 1:1”

Sorry I KNOW we already accept time dilation is a thing that occurs …Im just specifically asking if measuring the entropy of a black hole, also confirms the same things with no discrepancies.


r/AskPhysics 3h ago

Why does accelerating upward increase effective gravity?

1 Upvotes

Shouldn't it decrease or negate the effects of gravity? Gravity pulls you down, so you go up. Then why does effective gravity increase when riding in an elevator?

Also, why do people experience weightlessness in free fall? Isn't gravity still acting on them?


r/AskPhysics 1d ago

Is there a more effective way to visualize spacetime than a blanket with heavy weights on it?

49 Upvotes

This image is engrained in my brain because it’s just SO intuitive, but someone explained to me that this in not accurate because it requires gravity to work and uses circular reasoning.

Should I just shut up and trust the math? Of course my spatial reasoning is limited to three dimensions but now there is no model that sits nicely in my brain.

I’m working on learning the math required to understand but am curious if there is still a popular intuition among more rigorous or knowledgeable individuals

Thanks in advance!


r/AskPhysics 4h ago

How would a car with only 1 moving wheel move?

0 Upvotes

Hello!
I am creating a little rage game and a friend argued that the physics in the game are not accurate.
Essentially the idea is that you control a car with each wheel as a separate moving entity. The front wheels can only move forwards, the back wheels only move backwards.

My understanding of basic physics is that if I am moving one wheel, the car should rotate around itself ( the center of mass ) and if you move 2 wheels ( like the 2 front wheels ), the rotational vector should cancel out and be left only with forward vector, so move forward.

My friend disagrees. He thinks that if one wheel is moving while facing forwards, the car should move forwards regardless and no rotation should happen, because all of the wheels are straight.

Could anyone clear this up?
Maybe we are both wrong and the real answer is something else.
Or both are correct in different circumstances?

Thanks!


r/AskPhysics 23h ago

Are there waves associated with the weak and strong nuclear force?

23 Upvotes

The waves associated with the EM interaction are very well known and more recently we detected gravitational waves. Are there equivalents of those waves for the other two fundamental interactions? If so, how are they different?


r/AskPhysics 6h ago

E&M 2 ponder

1 Upvotes

If I get a empty box and fill it with electrons(or ions) scattering around, then apply a time dependent magnetic field through the box, how do the electrons move in the box? I feel like it’s a simple solution but modeling it gets finicky with lenz’s law


r/AskPhysics 7h ago

How do we know we know gravity isn't effecting our perception of how old the universe really is?

1 Upvotes

Was watching Interstellar (for the 5x time) last night and the Millers planet scene gave me a thought. Our estimation of the age of the universe is based on our perspective, however the perspective of a potential alien civilization could be different based on the gravity pulls of their local system. Is this factored into our calculations at all? Is it possible time in our system is accelerated/decelerated and that is why the universe seems so empty and could be throwing off our Drake equation theories?


r/AskPhysics 7h ago

Diffraction pattern from 5 slits

1 Upvotes

I am struggling to understand how the diffraction pattern from 5 slits is formed. How many maxima and minimum there are?

Also is the diffraction pattern a "modulated" version of the interference pattern?


r/AskPhysics 7h ago

Need Class 9 Physics module to clear up concepts 🔥

0 Upvotes

I am in class X and my coaching is about to start 11th grade (first 4 chapters in all subjects pcm)

and i wanted to clear up my concepts for class 9 like sound,gravitation,laws of motions, etc.

If anyone has their coaching module for physics and chem or any pdf of their module PLS PLS PLS SEND MAN I GENUINELLY NEED IT 😭


r/AskPhysics 20h ago

Why is curl of gradient always zero

7 Upvotes

The math gives zero but I'm looking for an intuitive explanation. I see from another reddit post that if there was curl, then a path will always loop back around to the same point, and that can't be possible because the gradient always points towards a point of higher elevation and that would be contradictory. But can't the curl be reversed mid path, bc the curl is a single value at every point, then the path won't loop back around and you won't end up with a contradiction where the elevation increases towards the lowest point, the point of origin?


r/AskPhysics 16h ago

Self study physics book follow up

2 Upvotes

Hello, I’m Kevin and am new to this group. I’d like to self study physics after having taken non-calculus physics > 30 yrs. ago. Forgot calculus and so is Young and Freedman inappropriate for me, or can I use AI or embedded software/book explanations to reteach myself ?? I use physics in my work as a research nurse practitioner at NIH, and I also just love physics. At work, I apply physics in: 1. XR Radiology; 2. Nuclear medicine; 3. MRI ; 4. Ultrasound; 5. Physiology of blood flow and respiration; 6. Optical properties of eyes and corrective lenses; 7. Heat transfer (temperature reg.); 8. Acoustics of hearing and sound conduction/transduction; 9. Mechanics related to motion, balance, etc.; and I could continue.

Would a non-calculus physics textbook be better, or am I missing important concepts by not using calculus to learn (re-learn more deeply) the concepts?? Can you all recommend a non-calculus textbook if you think it is better? Giancoli or Cutnell and Johnson? Thank you, Kevin


r/AskPhysics 1d ago

Is there a density at which objects emit photons?

17 Upvotes

I have no background in physics, but I wonder if objects that create light, for example, the Sun, emit photons at a set density. With that I mean, for example, 1 m2 of the surface of the Sun emits 1.8 × 10¹⁷ photons a milisecond (made up data for the sake of the example). Is thinking about light emission in terms of a “photon density” like this even meaningful?


r/AskPhysics 13h ago

Looking for a clue

0 Upvotes

I am doing research on an artist's work and trying to find the source for this image. It is supposed to be a model of some kind and it is linked to Heisenberg. The text on the artist's website makes no sense, since it talks about hydrogen-bombs.

Is anyone familiar with this image and can give me a source? The only thing looking vaguely familiar that I could find were still images of the "Trinity Test" shortly after the detonation.


r/AskPhysics 1d ago

Is it possible to get crystal clear images of extremely small scales?

6 Upvotes

I've been looking at electron micrographs of various cells. They're amazing, but still plenty blurry. I've learned enough about physics to know that there will be limits to how small a structure we can clearly 'see' with various imaging technologies.

For example, I understand you can't image things that are smaller than the wavelength of the light you're using. Given quantum theory, I assume that applies to all particle/waves, but I'd like to stick with visible photons for this question.

Is the blurryness in optical images of very small objects a result of our imperfect machines (machining tolerances, lens impurities etc)? If we managed to create an atomically 'perfect' microscope, would we be able to zoom in more and get super clear images, or are we basically at the limit now of what visible light will do?


r/AskPhysics 1d ago

If time and space are linked (connected, attached- however you want to phrase it) and both can be manipulated or warped by the mass of an object- does that mean time has physical properties? If so- can it be warped enough to travel back?

39 Upvotes

r/AskPhysics 8h ago

Evaporating primordial black holes as a "complex life wall"

0 Upvotes

A speculation I had recently: I've always been fascinated by black holes, and primordial black holes. The latter aren't known to exist but they're predicted by a lot of models and a bunch of JWST observations have increased the likelihood that they exist.

If primordial black holes exist, they might have been formed across the whole mass range. They're a candidate for at least some of dark matter for that reason.

But very small ones would already have evaporated, so the only ones left would be about asteroid mass or heavier.

That gets to my speculation. When a black hole evaporates (if we are right about how this works) it hits a runaway phase where it basically detonates, converting its remaining mass-energy into a shower of particles and radiation. The latter would include a lot of hard ultra-high-energy gamma rays. I've heard this put forward as a possible source for some of the very spicy photons we've detected.

If there was once a population of small ones that were evaporating, could this have resulted in a universe that until recently (in cosmological terms, so billions of years) was full of little evil bang-pop firecrackers that kept going off and spraying everything near them with ionizing radiation.

That could have more or less forbidden the evolution of complex life, technology, and spacefaring intelligences until "recently." (I'm aware of the other thing that might make us early in that regard, namely metallicity and early stars and planets probably being metal poor. Both could be true.)


r/AskPhysics 22h ago

why is an electric dipole a rigid body?

2 Upvotes

in a "dipole immersed in a electric field", why isn't either the external electric field pushing the 2 charges away or coulomb's law pushing them together, making the length between them change? and why are we doing torque calculations on them?


r/AskPhysics 1d ago

Cant you derive Newton's first law of motion from the second?

7 Upvotes

If there is no net force acting on an object, then F_net = 0

Since a = F_net / m

Then a = 0

So the object will experience no change in its state of rest or uniform velocity.

Why is Newton's first law distinct from the second?


r/AskPhysics 14h ago

Why are clouds all at the same height

0 Upvotes

Whenever its cloudy and i look up like 99% of hte clouds are at the same bottom level and have differnt heights but why, why aren't there some way higher up and lower to make it scattered?


r/AskPhysics 2d ago

As of now, is most of the mass within our universe concentrated in BHs or stars?

81 Upvotes

r/AskPhysics 1d ago

Escape Velocity is confusing

42 Upvotes

I understand that an object traveling at escape velocity will escape orbit for Earth, but I’m confused as to why it’s a velocity and not an acceleration.

If you’re accelerating upwards at just over 1G, wouldn’t that be enough to eventually get you out of orbit since you’re counteracting Earth’s pull?

And at which point do you need to be at escape velocity? Just at a single, specific altitude, or consistently at that speed? Because if I go to escape velocity and stop accelerating, won’t I just fall down rather than break away?


r/AskPhysics 1d ago

Do chaotic systems also limit how far into the past you can recreate?

7 Upvotes

My understanding of a chaotic system is this:

A system is chaotic if, due how it evolves over time, any change to the t=0 initial condition, no matter how small, will result in a noticeable change at some future point t=T

From my understanding, the laws of physics are time symmetric (in general - exceptions for weak force, entropy, expansion of the universe).

Does this mean if I observe a chaotic system at time t=0, I not only can't predict the system infinitely far into the future, but also can't retroject to time t=-T for some sufficiently large T?