**Ask a monkey a physics question thread**

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Originally Posted by CoccoBill

Moon's mean orbital velocity: 1.022 km/s
GPS satellites move at 3.9 km/s.

Now someone calculate how much of the time dilation disparity is due to gravity and how much due to velocity.

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This relative velocity is so tiny compared to c.
The gamma factor (the multiplier that tells the difference in relative time / space measurements) is

[gamma] = 1/SQRT(1-[beta]^2)

where [beta] is the ratio of a measured velocity to the speed of light,
i.e. [beta] = v/c
Note that all measured velocities are relative velocities.

3.9(10)^3 m/s - 1.022(10)^3 m/s = 2878 m/s ~= 3(10)^3 m/s

[beta] ~= 3(10)^3 / 3(10)^8 = 10^-5

[gamma] = 1/SQRT(1-[beta]^2)
= 1/SQRT(1-10^-10)
=1.000 000 000 05
= 1 + 5(10)-11

So the time dilation multiplier for a delta-v of ~3 km/s is "not 1" by about 5 seconds per hundred billion.

Exactly what I thought. I have no idea what you said.

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Originally Posted by CoccoBill

Exactly what I thought. I have no idea what you said.

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I'll clean it up to trim out the calculation.

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Originally Posted by CoccoBill

Moon's mean orbital velocity: 1.022 km/s
GPS satellites move at 3.9 km/s.

Now someone calculate how much of the time dilation disparity is due to gravity and how much due to velocity.

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The time dilation disparity due to velocity is 5 seconds every 100 billion seconds.
Roughly 1 second every 633.8 years.
Which is ~4.3 microseconds per day of the total discrepancy (66 µs/day),
leaving ~61.7 µs/day due to gravity.

In other words ong was wrong.

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Originally Posted by CoccoBill

In other words ong was wrong.

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OngBonga?

More like WrongBonga!


Got 'em.

I know time dilation is tiny at orbital velocity but I also expected gravitational time dilation to be tiny because the earth is not a black hole.

Only one order of magnitude out at a scale of billionths, that's not bad.

Close enough.
What's an order of magnitude between physicists?

How legit does this sound:

https://twitter.com/alexkaplan0/stat...44616528453633

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Originally Posted by CoccoBill

How legit does this sound:

https://twitter.com/alexkaplan0/stat...44616528453633

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Depends on whether you believe in rehabilitation. Surprised this guy isn't working for Big Wind, that's where all the money is...

https://www.nature.com/articles/d41586-023-02401-2

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Originally Posted by Poopadoop

Depends on whether you believe in rehabilitation. Surprised this guy isn't working for Big Wind, that's where all the money is...

https://www.nature.com/articles/d41586-023-02401-2

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Damn ftr not working on mobile browser. Anyway, I was trying to say already hours ago, that the one you're linking at is about different scientists and different methods, paper released a couple days ago.

https://arxiv.org/abs/2307.12008

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Originally Posted by CoccoBill

https://arxiv.org/abs/2307.12008

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Ok well it was put on a public server four days ago. Anyone can do that. I.e., it hasn't been submitted to a journal and gone through peer review, so I would not get too excited just yet.

From what I've gathered reading comments from people with impressive-sounding titles, it seems plausible, VERY interesting and likely a fraud.

A quick Google search on the lead scientist's name brings up dozens of scholarly publications and not 1 scandal or discrediting or dubious claims that were premature of his data.

That doesn't mean he's legit, but it rules out that he's obviously just getting his name in the press with a bold claim.

This is only a few days old. The physics of it is over my head, but what I've read doesn't set off any obvious alarm bells.

If true, OMG. Yuge news. The biggest news. All my friends tell me this is a great plan.

Eliminating resistive energy losses and the heat that ... well technically those are the same thing... eliminating the heat generated when current runs through a circuit pays off big time. If we can apply it at the scale of computer chips... it'd change the industry. If we can employ them on the scale of the international electrical grids, then it'd make a bazillion green energy options suddenly viable.

The stakes are so high that no one really wants to get excited ahead of time. Even if this is legit... can it be made at large scales relatively cheaply? Can it be made into circuit components? Wires? Does it require special protection or maintenance in any of these forms? Does it break down over time? Is it toxic?

A million things to know before we know what / how to be excited, IMO.

https://twitter.com/ESYudkowsky/stat...995286528?s=20

https://www.science.org/content/blog...conductor-news

I'm sure this is gonna turn out to be a nothingburger somehow, but I'm cautiously freaking out.

To me this just looks like we're scratching the surface now of technology that will only really be useful to us in the distant future. I'm in no doubt such a superconductive material exists, but whether it can be scaled up both in terms of application and production is an entirely different matter.

The diamond anvil experiments aren't really useful for regular applications. It's nice to know what happens inside planets but if a superconductor requires 1.5 million atmospheres of pressure to operate it's not going to be any use inside my computer. The more promising method seems to me like it will be nanotechnology, the forming of atomic lattices using pure carbon, silver and gold, under very specific geometries, that kind of thing. We're in the very early stages of that technology, this is possibly next century stuff.

https://twitter.com/8teAPi/status/1684385895565365248

https://twitter.com/andrewmccalip/st...33849781202944

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Originally Posted by OngBonga

The diamond anvil experiments aren't really useful for regular applications. It's nice to know what happens inside planets but if a superconductor requires 1.5 million atmospheres of pressure to operate it's not going to be any use inside my computer.

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This (claims to be/)is ambient temperature and normal atmospheric pressure though.

https://twitter.com/Andercot/status/1684339092635496449

The gossip I've gathered for the morning:


The "lead" scientist wasn't the lead after all, just the most prestigious name internationally.

The lead scientist I googled was tapped in mid-project to help with theory stuff. This is common in physics research.
He has published dozens of papers and no scandals around him, but his authority in this group is not overarching.


The initial paper published in arxiv *is* scandalous - at least in the authors listed if not in the content.

The initially published paper omits other contributors to the project in what appears to be a dick move to try to force the hand of the Nobel committee. Up to 3 people can share the Nobel Prize in Physics in any given year, and the initially published paper conveniently only listed 3 scientists' names as the authors of the paper.



Which... OK... so the experimental group is excited and nervous about getting their discovery scooped by anyone who knows how darn easy it is to make and test their material and claims. They clearly believe in it so much that they're worried about someone else stealing their credit. So much so that they've committed at least one no-no, scientifically speaking... they published a paper without giving due credit to everyone who contributed.

What other no-no's may they have committed?

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Originally Posted by MadMojoMonkey

The initial paper published in arxiv *is* scandalous - at least in the authors listed if not in the content.

Which... OK... so the experimental group is excited and nervous about getting their discovery scooped by anyone who knows how darn easy it is to make and test their material and claims. They clearly believe in it so much that they're worried about someone else stealing their credit. So much so that they've committed at least one no-no, scientifically speaking... they published a paper without giving due credit to everyone who contributed.

What other no-no's may they have committed?

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You would think if they were so concerned about being scooped they'd first send it to a journal for peer review, while keeping it in a private space on the public server (i.e., no-one can view it but they have a record of the date it was uploaded). Putting it on arxiv first means anyone who publishes first can claim they had the first report that passed peer review.

There's a little bit of info in here about the superconductor claim.

I have to agree with Sabine that the video of the broken wafer on a magnet does look a lot like diamagnetism.

I've done a demonstration where I condense liquid Oxygen out of the air and pour it between 2 strong magnets. It will "levitate" between the magnets, rather than fall through. Of course it evaporates in a matter of seconds so you have to look fast, but the effect is obvious.

The liquid oxygen is diamagnetic and experiences forces when a "steep" magnetic field gradient is incident upon it.
In more accessible terms... if the magnetic field changes from North to South over a "short" distance, that expresses a force on diamagnetic things.

https://www.youtube.com/watch?v=RjzL9cS3VW8

https://eirifu.wordpress.com/2023/07...mmary/#sbtable

Also, this just in

https://twitter.com/Andercot/status/...424691712?s=20

https://twitter.com/MichaelSFuhrer/s...46900284764160

After the disappointment this was a nice wrap-up.

It was too good to be true from the start, but I love the scientific process that got dozens of labs excited and confirming that while this new material has some interesting properties, it is not the holy grail of room temp. 1 atm superconductor.

I mean... we have no idea if this is even possible. There's no theoretical predictions that suggest they should be possible or that they are impossible. We're still babies when it comes to composite materials science. The better we get at manipulating atoms and molecules, the more we'll have these opportunities to search for a new material.

Just 'cause something sounds too good to be true doesn't mean it is. The internet is too good to be true. I pay someone a pittance in a monthly fee and I can talk to people anywhere in the world basically in live time? I have entire libraries at my fingertips? I can watch high quality entertainment whenever I want, and pause it, and skip commercials, too?

Amazing. It fits in my pocket, you say?

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Originally Posted by mojo

Amazing. It fits in my pocket, you say?

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I still find it hard to believe that people use phones for internet and watching stuff. A laptop infuriates me, I need my desktop with my nice monitor and mouse and keyboard the the rather important inability to drop it in the toilet or lose it on the bus.

I mean, sat-nav, directions, dirty google searches to settle a debate in the pub, horny pics for your other half, facetime chat, these things are all very well and good, that's fine using a phone for that. But watching a fucking movie? Really? Playing proper games? Conducting actual research? Spreadsheets and actual work? Fuck that.

Dunno if they still do it but I think it was pokerstars who gave an icon to people who were using a mobile phone to play their poker, and it was basically a "fish" note because who the fuck is playing high quality poker on a phone? It's basically some dude playing on his phone while his missus watches some reality tv shite.

Doing anything on a phone other than talking is a huge pain. Typing texts one letter at a time, squinting to read them, getting autocorrected into oblivion, fuck off. Just call the damn person and talk to them.

The only thing I use my phone for in real time other than talking is to use a hiking app 'cause my navigation skills are basically nil. I can literally end up half a mile from where I think I am and facing in a different direction.

I blame growing up in a perfectly flat town with a grid system of roads using numbers. There's no need to have any mental map whatsoever. You're on 5th street and need to get to 17th street? Go twelve blocks over. Here, you're on Charles street and need to get to Barlow Street? Turn on the satnav.

Boomers. I use my phone for everything, except for phone calls. Obviously at home my pc is the primary device, but when on the move. I wouldn't watch a movie on it at home, but I've watched several when traveling.

Phone calls are the last resort. The levels of aggression when seeking someone's attention go like this:

1. Email. Please respond when you have the time. Tomorrow or the day after are fine too.
2. IM. Please respond asap. I can wait a couple hours.
3. Phone call. Respond NOW. Drop everything you're doing, I'm your priority.

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Originally Posted by CoccoBill

Boomers. I use my phone for everything, except for phone calls. Obviously at home my pc is the primary device, but when on the move. I wouldn't watch a movie on it at home, but I've watched several when traveling.

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I was born in '68, boomers were '45 to '65 afaik. Not sure what my generation is called. I would go with the cool kids myself, but maybe that's just me.

Watching a movie on a phone is torture imo. I'd rather stare out the window of a train than do that.

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Originally Posted by CoccoBill

Phone calls are the last resort. The levels of aggression when seeking someone's attention go like this:

1. Email. Please respond when you have the time. Tomorrow or the day after are fine too.
2. IM. Please respond asap. I can wait a couple hours.
3. Phone call. Respond NOW. Drop everything you're doing, I'm your priority.

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There's something to this, but at the same time the phone is just a much more efficient way of communicating. You can get tone of voice, immediate feedback and clarification etc.. It's also more personal.

And, a text or email can be just as annoying as phone call, even more if they come over and over with the same thing. Ask any of the students I have who email me, then email me again an hour later because I haven't responded yet. Tbf, they'd be even more annoying if they were phoning me over and over too, but they never seem to cross that boundary.

Also, people in my experience (talking mainly about strangers here), are a lot more willing to be obnoxious on email than in person or on the phone.

It's also a lot easier to unintentionally come across as a cunt on email than it is in person or on the phone. One of our Heads of Dept. from several years ago actually was made to take an email awareness workshop because he was routinely coming across as a cunt on emails, enough so that multiple people complained to his superior (though tbh there's a good chance he was always a cunt, but he figured he could get away with it because it was email).

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Originally Posted by Poopadoop

Not sure what my generation is called.

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X like me, I think it's like '65-'80. I'm '74.

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Originally Posted by Poopadoop

It's also a lot easier to unintentionally come across as a cunt on email than it is in person or on the phone.

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Yeah absolutely. Missing the visual cues (expressions) is one thing, also missing the auditory ones (tone of voice) just makes it worse. There's emojis to remedy this but they only go so far and are mad easy to misinterpret. Like chatting on a forum. In a business setting these are less prevalent but routinely still lead to issues. I'm sure there's been murders and divorces that started from misunderstandings over chat tones.

Facial expressions and audible voice are physical phenomena btw so I guess we're on topic.

I'm Generation Formerly Known As Twitter

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Originally Posted by CoccoBill

Like chatting on a forum.

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I have no idea what you're talking about.

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Originally Posted by Poopadoop

I have no idea what you're talking about.

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What? That wasn't in reference to anything. At all.

Physics thread is for physics and sciencey convos.

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Originally Posted by MadMojoMonkey

Physics thread is for physics and sciencey convos.

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So why are you being hall monitor? That's not very sciencey.

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Originally Posted by CoccoBill

What? That wasn't in reference to anything. At all.

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I was joking.

I just upgraded my home PC and forgot my FTR password for a day.

Apparently, the FTR password reminder email service is broken.

But then I googled how to get Firefox to show me its stored passwords, and did that on my old PC, and I'm back, baby!

Old dog, new trick!
It's not necessarily science, but it is learning.

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Originally Posted by Poopadoop

I was joking.

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I know, so was I. Case in point.

https://twitter.com/moonyriott/statu...121691149?s=20
This shit again. I cannot believe a majority is saying A. What is wrong with these people?

I can't believe people would answer that physics-violating portals would behave in a way that violates physics.

Some people just lack common sense.

I sense sarcasm and I don't appreciate it!

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Originally Posted by MadMojoMonkey

I can't believe people would answer that physics-violating portals would behave in a way that violates physics.

Some people just lack common sense.

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I see no evidence that this portal defies the laws of physics.

The known laws, maybe. But that's not the same thing.

Anyway, the correct answer is A and oskar must be pretty dumb to think it's B. Imagine an open door moving towards you really fast. So long as you're stood in the right place (it's questionable if these folk on the train tracks are positioned correctly but let's assume so) then you'll be absolutely fine and there will be no transfer of energy. Your motion after going through the portal will be the same as your motion before you went through it, because of inertia.

I suppose the open door continues to move away from you at the same speed because it too has inertia. The problem here is the open door and portal analogy breaks down. The open door isn't taking us to another dimension, unlike the portal.

A is the better representation of the correct answer, but it's complicated because it's a three-dimensional representation of something patently not three-dimensional.

Portals defy physics on so many levels that it's hard to get in to. Can I just say the "No Cloning Principle" is at play here and be done with it?

***
Whether or not something is moving is a matter of perspective, not a universal truth.
Am I sitting still at my computer, or whirling around the sun at 30 km/s?
Why not both?

To the portal, the people are moving relative to it.

If you suggest the portal should plop the people out, then where does it plop them? They'd all enter the portal at the same location and if they leave with no speed, then they manifest as a plane, not even considering what the next person through would do.

If the argument is that there is some lack of motion which dominates the relative motion of the portal and people, then even the first person is problematic as the first molecules of theirs that come through the portal do not move away. Then the next molecules are put in the same space as the first, and we have real problems.

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Portals defy known physics on so many levels that it's hard to get in to.

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Fixed your post.

Any hypothetical portal that can exist in the future absolutely does not defy physics, its mere existence is absolute proof.

The problem with sci-fi stuff like this and debating whether such things are possible is that there's no clear definition, so to simply say "portals defy physics" is a pretty broad statement. I can prove it wrong by pointing out that a large imposing doorway is, by definition, a portal, and large imposing doorways don't defy physics, in fact I'd go as far to say we have an almost complete understanding of the physics of imposing doorways.

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If the argument is that there is some lack of motion which dominates the relative motion of the portal and people, then even the first person is problematic as the first molecules of theirs that come through the portal do not move away. Then the next molecules are put in the same space as the first, and we have real problems.

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lol at your puny 3D brain.

btw, have fun trying to define portals in such a way as to exclude wormholes.

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Originally Posted by OngBonga

The problem with sci-fi stuff like this and debating whether such things are possible is that there's no clear definition, so to simply say "portals defy physics" is a pretty broad statement. I can prove it wrong by pointing out that a large imposing doorway is, by definition, a portal, and large imposing doorways don't defy physics, in fact I'd go as far to say we have an almost complete understanding of the physics of imposing doorways.

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True, but if you're standing still and I throw a door at you, you're still wrong.

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Originally Posted by OngBonga

lol at your puny 3D brain.

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https://www.shutterstock.com/shutter...1558900451.jpg

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Originally Posted by OngBonga

btw, have fun trying to define portals in such a way as to exclude wormholes.

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The proof Big Science doesn't want you to know.

Check out the extensive visual documentation on wormholes I found.
https://cdn.w600.comps.canstockphoto...sp16275522.jpg

I think one rule of portals is pretty clear and that is that you can walk through it. If the inertia doesn't carry over, then you wouldn't be able to walk through it. As soon as any part of you would cross the threshold it would stop dead. So you'd either get turned into soup or at least get stuck. Getting stuck is not part of portal lore.

It also has to be taking you to another dimension, or teleporting you, because if you walk behind the portal there's no obvious place where it's all happening. I'm less inclined to think that teleportation is possible, seems like that's severing your body as you walk through. It's kind of important to still be in causal connection with the rest of your body as you move through the portal. Instant teleportation might be possible, but you can't instantly walk through a portal.

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Originally Posted by oskar

I think one rule of portals is pretty clear and that is that you can walk through it. If the inertia doesn't carry over, then you wouldn't be able to walk through it. As soon as any part of you would cross the threshold it would stop dead. So you'd either get turned into soup or at least get stuck. Getting stuck is not part of portal lore.

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When you said inertia, I think you meant momentum.

Inertia is kinda a tricky word because in physics it kinda means mass. There are no "inertial forces" in physics - what people usually mean when they say that is what a physicist would call momentum.

The problem with portals and momentum is that momentum isn't a universal property of an object. An object's momentum is the product of its mass and its velocity, p = mv. (IDK why we use p for momentum, but there it is.) It's the velocity part that's tricky. Whether an object is moving or not is a matter of perspective. Whether 2 things are moving relative to one another is universal, but the rate at which they move relative to each other can be different to different observers. It will always be the same to the 2 objects, though.

So with an object moving relative to a portal, it's that relative motion of the 2 relative to each other that would seem to matter.

However, ong brought up a great point by bringing up causal links. A pair of portals has to be causally connected to qualify as portals, I think. In a sense they are the opposite sides of a 2D object that exist at different points in spacetime. Going into 1 means coming out the other. That's a causal link.

So now here's another problem with momentum.

If the 2 portals are somehow connected in a single location such as opposite sides of a 2D object, then which portal's relative motion to the object going through it matters? The one it enters or the one it exits? In the above example, these are not the same.

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Inertia is kinda a tricky word because in physics it kinda means mass. There are no "inertial forces" in physics - what people usually mean when they say that is what a physicist would call momentum.

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Huh? There certainly are inertial forces. Coriolis, centrifugal, centripetal, and the biggie... gravity, aka know as "fictitious forces" because they only emerge in a non-inertial frame of reference, that is an accelerating or rotating frame of reference. But doesn't literally everything with mass (except maybe black holes) exist in a non-inertial frame of reference? Assuming it's not a singularity, then it has gravitational interactions with itself. So everything with mass that isn't a black hole exists in a non-inertial frame of reference, and therefore experiences inertial forces.

Inertia is indeed basically mass, but it's better defined imo in layman's terms as "resistance to a change in state of motion". Linking that concept to mass isn't easy, but we all understand that an object with mass requires a force to set in motion so the intuition is just about there.

Momentum is inertia * velocity. If two identical objects are moving at different velocities, they have the same inertia but different momenta.

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Originally Posted by OngBonga

Huh? There certainly are inertial forces. Coriolis, centrifugal, centripetal, and the biggie... gravity, aka know as "fictitious forces" because they only emerge in a non-inertial frame of reference, that is an accelerating or rotating frame of reference. But doesn't literally everything with mass (except maybe black holes) exist in a non-inertial frame of reference? Assuming it's not a singularity, then it has gravitational interactions with itself. So everything with mass that isn't a black hole exists in a non-inertial frame of reference, and therefore experiences inertial forces.

Inertia is indeed basically mass, but it's better defined imo in layman's terms as "resistance to a change in state of motion". Linking that concept to mass isn't easy, but we all understand that an object with mass requires a force to set in motion so the intuition is just about there.

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It's the difference between colloquial language and scientific jargon.

In physics, there are no inertial forces. What a colloquial speaker would call an inertial force is not a force at all. It's just Newton's Laws of motion. In an inertial reference frame, a moving object will continue moving in a straight line at constant speed if and only if the vector sum of forces acting on it is 0 N. A *lack of force* is responsible for inertial motion.

The phrase inertial force comes from a misunderstanding of the laws of motion. It's based on an assumption that an object with no forces acting on it will be still. To put it another way, it assumes that the reason for motion is forces. This seems pretty true in a macroscopic world with friction causing most movements to slow and stop. If you don't keep applying a force, it will stop. It fails to appreciate that friction is a force, and that the stopping of the motion isn't due to a lack of forces, but due to a stopping force.

Per your question on reference frames: Things aren't in any given reference frame, inertial or otherwise. A reference frame is a perspective. From some perspectives, Newton's Laws hold, and those perspectives are called inertial reference frames. From other perspectives, Newton's Laws are simply not true*; these are called non-inertial reference frames.

There is no universally "prime" reference frame from which we could say an object is "truly" at rest in any sense. The laws of physics we have simply don't care whether or not you're moving. We have the mathematical framework to assert a reference frame that is helpful for a human to understand the relationships and consequences of interactions.


*Better to say they don't apply than to say they're not true. Each of Newton's laws of motion contains the phrase, "in an inertial reference frame." So if you're not in an inertial frame, it's not exactly that Newton's Laws are untrue, just that they specifically don't apply.

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Originally Posted by OngBonga

Momentum is inertia * velocity. If two identical objects are moving at different velocities, they have the same inertia but different momenta.

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Each object is always at rest in a reference frame that moves and rotates along with it.

The relative motion is universal, but the absolute motion is not.


FYI, in my physics department, you'd get a -1 on anything you turned in that said "inertial force" in it. There'd be a note on the side correcting that term to whatever would be more appropriate in that context.


I appreciate that colloquial speech isn't any less correct than scientific jargon. I absolutely code switch when I'm talking at work vs. when I'm talking to a layman. If you and I are talking and you keep saying inertial force, I'm unlikely to correct you more than once. If you know that I expect a different word, but you choose to use your word, that's fine. Communication requires cooperation, and semantics isn't a hill I'd choose to die on.

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To put it another way, it assumes that the reason for motion is forces.

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The reason for acceleration is forces. There's a fundamental difference between motion and acceleration. One is a constant and the other is a change.

An inertial force is a fictitious force because it's emergent. It's not a real force, so I appreciate that in physics jargon, and what "force" means in physics, it's inaccurate. It's a fictitious force because it's not accelerating, it's the frame of reference that's accelerating, giving the illusion of acceleration, and therefore a force.

But what I was getting at is this... is that exactly what all forces are? An illusion? Take friction. What's happening on the Plank scale? I'd hazard a guess that particles move in a straight line at a constant speed in very curved space, giving the macro illusion of acceleration. So from the FoR of an individual particle, it's not experiencing acceleration, and therefore no force, and actually all that's happening is spacetime is locally more curved.

Maybe. I'm just talking shit here but the concept of a "force" is ambiguous at the best of times, even in physics where you try to define it accurately. In basic language, it's something that causes an acceleration. But we then have to understand what acceleration means, and that's ambiguous too, especially at Plank scales where we don't actually know what's really happening.

So it might be that all forces are inertial forces and that term deserves more respect!

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Originally Posted by OngBonga

The reason for acceleration is forces. There's a fundamental difference between motion and acceleration. One is a constant and the other is a change.

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Hmmm... so you're saying dr/dt is a constant (where r is the vector describing an objects instantaneous position)? ...because the universe doesn't hold r itself in any exclusive regard..?

Bold, yet controversial. I like it.
Not necessarily agreeing with it, but I like the train of thought.

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Originally Posted by OngBonga

An inertial force is a fictitious force because it's emergent. It's not a real force, so I appreciate that in physics jargon, and what "force" means in physics, it's inaccurate. It's a fictitious force because it's not accelerating, it's the frame of reference that's accelerating, giving the illusion of acceleration, and therefore a force.

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Hmmm... so you're putting it in the same category as centrifugal force?
Or you're saying centrifugal force is a type of inertial force, which are themselves "fictitious" forces..?

That's at least a consistent definition. I can jive with that.

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Originally Posted by OngBonga

But what I was getting at is this... is that exactly what all forces are? An illusion? Take friction. What's happening on the Plank scale? I'd hazard a guess that particles move in a straight line at a constant speed in very curved space, giving the macro illusion of acceleration. So from the FoR of an individual particle, it's not experiencing acceleration, and therefore no force, and actually all that's happening is spacetime is locally more curved.

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On the plank scale, it's all wave functions and energy levels.

Whether you put forces on a pedestal, or pressure, or acceleration, etc... whichever of those you hold as "fundamental" is fine, because at the end of the day, the relationships between those values is what it is. I.e. if particles exert point-like forces on each other, that's one thing. If the distortion of wave functions exerts a pressure on the wave functions it interacts with, that's a slightly different thing. But both describe the exact same physics, so which one you put on the "fundamental" pedestal isn't consequential.

Certainly, the mass of particles curves spacetime, but the relative strength of gravitation at that scale compared to the strengths of the Electromagnetic, Strong and Weak forces is tiny. It's there. It matters. But much less than the other 3 forces. Well, the Weak force isn't doing much, but it is there and still stronger than gravitational forces.

All that said... friction is one of the least understood things in physics. We can only measure it and report the measurements. We have no predictive model for what the coefficient of friction will be between 2 materials. We just have to do the experiment and measure it.

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Originally Posted by OngBonga

Maybe. I'm just talking shit here but the concept of a "force" is ambiguous at the best of times, even in physics where you try to define it accurately. In basic language, it's something that causes an acceleration. But we then have to understand what acceleration means, and that's ambiguous too, especially at Plank scales where we don't actually know what's really happening.

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Is it really that ambiguous? F = ma. That's a solid definition. We can measure m and r (again a position vector). If the vector r is not constant in time, then it changes, and we can calculate that change using calculus. v = dr/dt, with v the velocity and dr/dt the instantaneous rate of change in the position, defined in the limit as t goes to 0 s. Then if v is not constant, we can do that again, with a = dv/dt.

All of this is well defined for macroscopic objects to within the uncertainty of measuring position.

On the quantum scale, all of this is still true. It's just that now we're talking about the time evolution of a wave function and the movement of a probability function through space in time. But the fundamental laws of how to define velocity and acceleration are intact. We just have to rethink how we describe position. It's no longer exactly measurable, but a probability density function. We can't know the exact position, but we can calculate the expected values of position we may find when measuring it. The evolution of those expected values in time follows the same physics - v = dr/dt and a = dv/dt.

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Originally Posted by OngBonga

So it might be that all forces are inertial forces and that term deserves more respect!

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Dunno.

I'm personally opposed to the phrase "fictitious forces" because of what you mentioned. Those forces are NOT fictitious in non-inertial frames, and there's no reason the universe has to favor inertial frames just 'cause our puny human brains find them easier to work with.

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Originally Posted by mojo

Hmmm... so you're saying dr/dt is a constant (where r is the vector describing an objects instantaneous position)? ...because the universe doesn't hold r itself in any exclusive regard..?


Bold, yet controversial. I like it.
Not necessarily agreeing with it, but I like the train of thought.

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I'm not sure about the dr/dt thing but it's not controversial that a force causes an acceleration. An inertial force will give the illusion of acceleration in a non-inertial FoR.

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On the plank scale, it's all wave functions and energy levels.

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Wave functions are a mathematical description of reality, not a physical description. Even string theory isn't physical, the strings are waves not actual strings, it's just convenient for us to think of them as strings because we can visualise different wave geometries. The wave function doesn't tell us what the Planck scale looks like, just how it behaves.

What's actually happening is anyone's guess. We literally can't see it with light because to do so requires a photon with a wavelength shorter than the Planck length, and the energy of such a photon would create a black hole.

I gotta go to work, back later.

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Originally Posted by OngBonga

I'm not sure about the dr/dt thing but it's not controversial that a force causes an acceleration. An inertial force will give the illusion of acceleration in a non-inertial FoR.

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I don't think that's consistent, anymore.

When you were describing the "fictitious" forces as "inertial" forces, at least there was a consistent classification.
I think you lose that when you try to go the other way.

IDK what you're describing in an inertial reference frame that you'd consider an inertial force.

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Originally Posted by OngBonga

Wave functions are a mathematical description of reality, not a physical description. Even string theory isn't physical, the strings are waves not actual strings, it's just convenient for us to think of them as strings because we can visualise different wave geometries. The wave function doesn't tell us what the Planck scale looks like, just how it behaves.

What's actually happening is anyone's guess. We literally can't see it with light because to do so requires a photon with a wavelength shorter than the Planck length, and the energy of such a photon would create a black hole.

I gotta go to work, back later.

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Well... it is a model, and not reality. That is important to keep in mind.

Nonetheless, the model makes excellent predictions, even on these scales. We absolutely can describe how atoms bond to each other to make molecules and crystals by understanding how those mathematical models interact with each other. Even given the fact that those actual equations are by and large unsolvable in the exact sense, and we have to make simplifications to get them into something that is close, but solvable. Which is just astounding. Amazing, even. Miraculous, I'd say.

So you're right that the model isn't the Truth, but what it can't describe isn't the *what*, it's the *how* things happen. It is remarkable at "what will happen" predictions, but silent on "why it do like that?" answers.


String theory is misnamed. It's not a theory, scientifically speaking, it's a hypothesis, or rather, a collection of hypotheses. Better still, it's a collection of inconsistent hypotheses which have not drawn 1 verifiable prediction in the many decades it's been mulled over by some allegedly very smart people.

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Originally Posted by mojo

Certainly, the mass of particles curves spacetime, but the relative strength of gravitation at that scale compared to the strengths of the Electromagnetic, Strong and Weak forces is tiny.

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Is it though? It's tiny on the macro scale, but gravity obeys the inverse square law. So as you increase your distance by 2, the force gets weaker by a factor of 4. But let's think about the reverse of that. What happens if you half your distance? The force gets stronger by a factor of 4. So now let's move into the Planck realm. How strong is gravity now when you're one or two Planck lengths away from the source? Of course tidal forces become insane at this scale too, because the force on one side of an object with mass is absurdly more than the other side, because one side is relatively so much closer to the source of gravity than the other side. When you also consider that both objects apply a force on each other, then it seems there's a critical point where the gravity of a particle becomes so absurdly strong that it's basically acting no differently to a black hole. It's possible, at least from my uneducated pov, that the Planck length is the quantum version of the event horizon. To enter is to never return.

As for string hypotheses, well this is another excellent mathematical description of the universe and I'm not sure how you can disregard that so casually while insisting the wave function is fundamental. String theory makes excellent predictions if we imagine a universe with 11 dimensions. That itself is its prime prediction as best I'm aware, that there are many more dimensions, it doesn't work otherwise.

idk about other dimensions, it's hard to really know what it even means. But if a hypothesis says "the universe makes perfect mathematical sense if there are 11 dimensions", and that mathematics checks out, then it's worth the attention it gets.

Electromagnetic forces also obey an inverse square law. It's the exact same equation as Newton's Law of Gravity, just with the letters changed.
Compare this F_g = GMm/r^2 to this F_q = KQq/r^2. The only difference is the letters, which are variables.

More importantly, notice that when you divide one by the other, the r^2 parts cancel out. Thus the relative strength is not a function of the distance between the 2 particles of masses M and m and charges Q and q.

The strong force is much more complicated, but we find again that it dominates gravity on small scales.


As for the singularities (infinities) at the location of the particle, remember that the universe doesn't allow the position of a particle to be exactly defined. So over any measurement's time scale, we'll see a "smearing out" of the charge/field/force created.


There is no complete string hypothesis that describes the whole of QM. String hypotheses only match known physics where the creators of that hypothesis have literally forced it to be the same. That's all well and good, but no verifiable predictions have been made where they can't be forced to be the same. If you add enough terms to a polynomial, you can exactly fit any data set, but that doesn't make the polynomial physics. If you can't understand what each variable is in physical terms, then you can't trust anything about it. Just adding terms and forcing compliance is fine and all, but if doing so doesn't actually add *anything* to the field of study, then ... it's not anything. Maybe someday there will be a string theory, but there simply aren't anything but bad guesses that yield no new science thus far.

Yes but the difference between EM and gravity is that diamagnetism repels, so the closer two objects get, the more force it requires to bring them closer, ultimately approaching infinite energy. Gravity is attractive so it takes less energy the closer two objects get, it would approach infinite energy to stop further gravitational motion. So gravity can easily dominate EM at Planck scales.

idk about the strong and weak forces because frankly I have absolutely no idea how they work. EM is largely magical to me still, though it's easier to somewhat understand. Gravity is the easy one, at least at macro scales.

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So gravity can easily dominate EM at Planck scales.

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Actually this isn't true, I'm failing to realise that there's just an outright war between gravity and EM at this scale, the EM will repel against the gravity and the gravity will fight the EM. I'm not sure which dominates.

To understand gravity is to understand that it's a purely geometric theory. Wrapping your head around the distortion isn't easy, and the distinction between space and time isn't clear for different observers, so it's still an absolute beast and when I say "understand" I mean at the most basic level. But that's still more than the other forces.

I'm of the opinion that the other forces are also geometric in nature and can be described as straight-line constant motion though insanely curved spatial dimensions. This is why I like string theory sorry hypothesis, because it brings into importance these other dimensions. But I'm not bound by rigorous science so maybe that's why I'm happy to indulge in it.

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Originally Posted by OngBonga

Yes but the difference between EM and gravity is that diamagnetism repels, so the closer two objects get, the more force it requires to bring them closer, ultimately approaching infinite energy. Gravity is attractive so it takes less energy the closer two objects get, it would approach infinite energy to stop further gravitational motion. So gravity can easily dominate EM at Planck scales.

idk about the strong and weak forces because frankly I have absolutely no idea how they work. EM is largely magical to me still, though it's easier to somewhat understand. Gravity is the easy one, at least at macro scales.

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Both forces approach infinity as the distance between the 2 particles interacting goes to 0 m.
but one approaches infinity about 100 times faster than the other. The weaker one is gravity.

It cannot dominate unless we're talking black hole (or other exotic matter like neutron stars) conditions... individual particles are not black holes. The spreading out of the wave function is part of that - the pointlike nature of particles may intuitively indicate they have no measurable size, but the wavelike nature confounds that. While we cannot measure any size of the electron, e.g., we also don't measure infinities in the gravitational or electric fields or any fields when we look at them as closely as nature allows (and we know how).

The uncertainty principles do a lot of heavy lifting when we start talking about attractive electric and magnetic forces. The more confined an electron's orbital shape becomes, the less certain its momentum becomes. The universe precludes highly accurate descriptions of position and momentum. This isn't a human thing, or a measurement thing. There are additional human and measurement things which make the uncertainties grow even more than the universal minimum. But there is a universal minimum. That minimum makes the infinities of precisely located, pointlike particles a non-issue.


IDK what you're trying to say about diamagnetism. Like charges repel, too. The repelling force of like charges (outside of the strong force interaction) is about 100 times stronger than the attracting force of gravity between charged particles. It varies depending on which particle of how much mass and electric charge, and that factor of 100 is only a ballpark.

Of course, for uncharged particles, the electric force and magnetic forces between them are 0. Strong forces still apply, say to hold protons and neutrons together, with the neutrons lacking (net) electric charge. We do see situations in nature where gravitational forces are on par with nuclear forces in Neutron stars.

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Originally Posted by OngBonga

Actually this isn't true, I'm failing to realise that there's just an outright war between gravity and EM at this scale, the EM will repel against the gravity and the gravity will fight the EM. I'm not sure which dominates.

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I think I've addressed this in my prior post.

Those 2 forces are at war, as you say, but the ratio of their strength is constant - the distance between them cancels out when you calculate the ratio of electric to gravitational forces, because both forces are [some constant]*[particle properties]/r^2. When you divide them to show the ratio, the r^2 terms cancel, and we see that all that matters to that ratio is the constants and the particle properties, not the distance between the particles.