The inverse stare law.
this post was submitted on 05 Nov 2023
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π nice one
I don't understand the formula, but I understand Mr. Bean. +1
If you have two charges q1 and q2, you can get the force between them F by multiplying them with the coulomb constant K (approximately 9 Γ 10^9) and then dividing that by the distance between them squared r^2.
q1 and q2 cannot be negative. Sometimes you'll not be given a charge, and instead the problem will tell you that you have a proton or electron, both of them have the same charge (1.6 Γ 10^-19 C), but electrons have a negative charge.
q1 and q2 can be negative. The force is the same as if they were positive because -1 x -1 = 1
In this case yes, but if q1 was -20ΞΌC, q2 was 30ΞΌC, and r was 0.5m, then using -20ΞΌC as it is would make F equal to -21.6N which is just 21.6N of attraction force between the two charges.
If they are oppositely charged particles, I would expect that there is a force of attraction acting on them, yes.
I am not saying that's wrong, just that there's 21.6N of attraction force between the two charges not -21.6N.
But those are the same thing.
No, if the force is negative it acts in the opposite direction
Yes, and a force acting in the opposite direction of the distance is an attractive force.
But that if both are negative not one pos one neg like the previous commenter gave in their examples, so the true formula has an absolute value in the numerator: |q1Xq2|
No, but there should be a minus in the Coulomb formula
G is a constant,
m is mass,
d is distance from each other starting from their center of mass,
This measures gravitational force, F
edit: fix similarities typo
Awesome to see the similarities between: Newtonian Mechanics and Quantum mechanics
Coulomb's law was essential to the development of the theory of electromagnetism and maybe even its starting point, as it allowed meaningful discussions of the amount of electric charge in a particle.
Here, ke is a constant, q1 and q2 are the quantit>ies of each charge, and the scalar r is the distance between the charges.
Being an inverse-square law, the law is similar to Isaac Newton's inverse-square law of universal gravitation, but gravitational forces always make things attract, while electrostatic forces make charges attract or repel. Also, gravitational forces are much weaker than electrostatic forces. Coulomb's law can be used to derive Gauss's law, and vice versa. In the case of a single point charge at rest, the two laws are equivalent, expressing the same physical law in different ways. The law has been tested extensively, and observations have upheld the law on the scale from 10β16 m to 108 m.
It's electromagnetism you mean, not quantum mechanics.
Guess what electromagnetism turned out to be
They're different things. The OP means electromagnetism, Coulomb's law has nothing to do with quantum mechanics, it's classical physics.
Quantum electrodynamics though
Okay but tell me, what theory superceded electromagnetism?
Sure, EM is still useful, I use it in my work, but in the end, it all boils down to QM.
"X depends on or is built up on Y" does not imply "X is Y". Concepts, laws, techniques, etc. can depend or be higher-order expressions of QM without being QM. If you started asking a QM scientist about tensile strength or the Mohs scale they would (rightly) be confused.
Yes, of course. Coloumb and Maxwell had no idea about QM when they were developing their ideas. Not to mention that these higher-order abstractions are just as valid as QM (up to a point, but so is QM). Depening on the application, you'd want to use a different abstraction. EM is perfect for everyday use, as well as all the way down to the microscale.
My point is that EM is explained by QM, and therefore supercedes it. You could use QM to solve every EM problem, it'd just be waaaaay too difficult to be practical.
I feel like you're using "supercede" differently to the rest of us. You're getting a hostile reaction because it sounded like you're saying that EM is no longer at all useful because it has been obsoleted (superceded) by QM. Now you're (correctly) saying that EM is still useful within its domain, but continuing to say that QM supercedes it. To me, at least, that's a contradiction. QM extends EM, but does not supercede it. If EM were supercedes, there would be no situation in which it was useful.
Guys guys, yesterday I ate some hot wings and then shit myself on the way to the toilet π€£πͺπ―
Also can you really solve all em equations with qm? I always thought the laws broke down from one to the other? So youβre saying going from em to qm the laws break down but going from qm to em the laws hold up?
Huh? Not sure what the first part of your comment means but I'll give it a go...
Quantum mechanics basically explains all interactions between particles/waves (take your pick, it's all the same) except gravitational interactions. You can use the laws of QM to solve any problem you'd have if you were studying electromagnetism, in fact you can derive versions of EM directly from QM. EM will start breaking down at small scales, we're talking 10^-9 m ish. It'll still be accurate, you'll just notice your data will be off from your calculations the smaller you go. You can exploit QM effects to be tangible/visible on larger scales, but it takes some work. QM only starts breaking down at the Planck scale, which is suuuuuuper small. We can't observe anything that small yet so it kinda doesn't matter. It'd be nice if we had a theory that did, though.
The first part was me being humbled by the intellectual conversation and it going way over my head so I said the dumbest thing I could think of to level it out. But then I reread it and learned something. Planck scale being built up from minimum units? Iβm assuming this is what string theory is attempting to do? Also donβt you find it kind of stupid that the largest size is 10m^26 and the smallest is 10m^-35 and we naturally observe the universe closest to 10m^0? Like weβre right in the middle of that? Seems obvious that looking in each direction and hitting a wall is analogous to naturally looking into the distance and only being able to see so far and looking closely and only being able to see so far.
Oh yeah, that's super interesting! I think our understanding of the universe (and conseqentially, our theories) are a byproduct of our place in the universe. If we were on a smaller scale and still had the same intelligence, perhaps we could peer deeper in one direction, at the cost of the other. I think there could be infinte complexity hiding just beyond our reach.
Quantum mechanics didn't supersede electromagnetism. Again, they're different things. Electromagnetism is a fundamental interaction. Whereas quantum mechanics describes the mechanics of quantum particles. Whether those particles are affected by electromagnetic forces or not. It's a description of how they behave at quantum scales.
Coulomb's law has nothing to do with quantum mechanics, it's a description of how macroscopic charged particles interact. What the OP should have said to be correct is:
Awesome to see the similarities between: Newton's law of gravitation and Coulomb's law
I don't know where he got quantum mechanics from.
Coulomb had the last laugh though because Newton's theory has been superseded by relativity.
What was you doing step gravity?
-Time, probably
So has Coulomb's theory
If there's anyone who can, please let me know if the similarities between these two formulas imply a relationship between gravity and electrical attraction or hint at a unified theory, or if it's just a coincidence or a consequence of something else.
The relation between them is that they're both forces that scale with the inverse square of the distance between the objects. Any force that scales with the inverse square of distance has pretty much the same general form.
Another similarity is that both are incomplete, first approximations that describe their respective forces. The more complete versions are Maxwell's laws for electromagnetism and General Relativity for gravity.
There's some relation in that they both act on fields, but the things that affect those fields are very different (higgs bosons and electrons respectively) and the relationship between all that for an 'unified theory' is a topic of much research. IANAP though (not a physicist)
Are higgs bosons supposed to be gravitons? I think you're confused about how some particles aquire some of their mass, and how all mass behaves.
Electromagnetism and gravity are both mediated by massless bosons; photons and gravitons respectively. This is why both forces follow the inverse square law.
I don't think there's any evidence for gravitons yet, and gravity hasn't been quantized. I'd say it's this similarity that's the best argument of quantum gravity, not the other way around.
Fair. The masslessness of the bosons that should mediate gravity, along with them being spin-2, can however be deduced from the properties of gravitational waves.
We know that gravity is a wave that travels at the speed of light, this has been experimentally measured many times. If it is also quantized (a very reasonable ~~symptom~~ hypothesis since everything else that we've ever seen is) then by definition there are particles that carry gravity.
If gravity is continuous then we would end up with something like the ultraviolet catastrophe but for gravity.
Hmm, I hadn't considered an "ultragravity catastrophe". I wonder if this could accout for dark energy or the supposed inflatons? Probably not, the catastrophe suggests infinite energy, not just lots of energy, eh?
The ultraviolet catastrophe was averted due to the discreet nature of electrons though, and I don't recall gravity behaving as a blackbody radiator anyway. Would this come into effect at horizons?
Sorry, I think I came off as too confident in my previous comment. I'm quite sure about my first paragraph but the rest is just speculation from an amateur.
If I would risk speculating even further though, there's some similarity in the sense that infinities indicate a problem. In the ultraviolet catastrophe the infinity arises from the energy of arbitrarily short EM wavelengths. With gravity it arises in the density of black holes. It seems unreasonable that it would actually be infinite, and it's possible that quantization of gravity plays a part in preventing that from happening.
massless bosons
Why do I feel like I've been insulted
The most accepted theory among physicists is that "shit's crazy, yo".
There is one thing particularly interesting, and that is that the inverse square laws appears again. It appears in the electrical laws for instance.
That is electricity also exerts forces inverse to the square of distance with charges. One thinks perhaps inverse square distance has some deep significance, maybe gravity and electricity are different aspects of the same thing
...
Today our theory of physics, laws of physics are a multitude of different parts and pieces that don't fit together very well. We don't understand the one in terms of the other. We don't have one structure that it's all deduced we have several pieces that don't quite fit yet.
And that's the reason in these lectures instead of telling you what the law of physics is I talk about the things that's common in the various laws because we don't understand the connection between them.
But what's very strange is that there is certain things that's the same in both
Richard Feynman and 45:48 https://youtu.be/-kFOXP026eE?si=hAIvDhWVGxMOvEi1
Always upvote Feynman. Got me through some tough times in undergrad.
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It's really simple, they are both radial fields with a 1/r potential, thus a 1/rΒ² force. Newtonian gravity is just a weak field approximation of general relativity, where you have very different equations, for example Einsteins field equations.. One electric charge creates an electric field, and another charge will interact with it, but the motion itself still depends on the mass of the second charge. Matter instead curves spacetime itself, and the curved spacetime tells matter how to move. Source: MS in physics.
Doubtful but interesting thinking. Itβs actually a rather simple equation that explains how two equally weighted forces affect one another over distance. The numerator expresses that both forces carry equal weight in the interaction (if they are both the same kind of force, eg gravity or electromagnetism, this makes sense) and they are constructive interactions (both add to the intensity of the interaction) hence multiplying one by the other. The denominator just indicates that the distance between the two things exponentially degrades the force at a power of 2, since the force is spreading out in 2 dimensions (imagine a cone starting at one point and extending to the second, so that when you reach the second point the force is spread across the cross section of that cone, but the only part of the force affecting that second point is the part that touches it).
Now that's just not fair, Coulomb was born way after Newton. At least make Newton a zombie for realism.
Newton: "FagMad!"
Coulumb: "Fuckyouare!"