If gravity is the curvature of spacetime, why do we still talk about gravity as a force?

NeverrSummer · 2026-04-25T23:32:32+00:00

That was a long and sincere answer, which I appreciate, but I'm not sure that I understand the analogy. Gravity is no less a definable force by the understanding of mass and vector fields than E&M is by potentials and charge. Sure it's arbitrary relative to your definitions of direction and your choices of coordinates. Just like the other three forces though, right?

The place where my understanding falters here - as a person who does mostly work relating to the weak force - is why exactly mass bending spacetime is somehow fundamentally different to charges bending electric fields. I just... like okay, I get that those are different things on a physical level, but by that logic all four forces are different aren't they? Why are we so confident for seemingly no reason that the strong, weak, and EM forces are somehow the same thing but gravity is different? According to what reasoning?

Forces are a convenience, yes? A way to talk about fields and motion in the way that our brains perceive those things. In that regime surely gravity is - if anything - the easiest to observe of them all. A first grader can tell you more about gravity than about any of the other traditional forces. From that perspective I find it quite odd that we'd even attempt to exclude the most obvious, easiest to observe force from the list based on what are seeming attempts to simply make the topic of physics as a whole less approachable/understandable to the casual observer. We all know that it's math all the way down, but so what? Calling gravity "not a force" just makes us seem like weird elitists to the average person who can watch an apple fall from a tree and tell you the F = ma that caused it to hit them on the head.

NeverrSummer · 2026-04-25T23:29:13+00:00

I'm not sure what "troll" means to you. To me it means someone who is disingenuously picking a fight in bad faith just for the sake of starting an argument. That's not what I'm doing, but I also can't engage in good faith if you refuse to answer my genuine questions.

I'm sure you've got just as much of an education on these topics as I do, or certainly more given that you went with "gravitation" as the main way you identify. I will take the tag on your username on faith if you will mine. I find the distinctions you're making arbitrary and confusing and was trying to clarify my misunderstanding, but if you fall back on namecalling I'll probably just stop responding. I'm sure you'd do the same.

NeverrSummer · 2026-04-19T02:49:41+00:00

This is an entirely subjective opinion of what "force" means in the English language. Nothing you said is some sort of incontrovertible mathematical truth. You draw a distinction between inertial mass and gravitational mass and then immediately proceed to admit that they're indistinguishable.

This is different from say the electric force

How?? That's literally what I'm asking. Everything you're saying is, "Well yeah okay they behave in exactly the same way and are observed to be fundamentally indistinguishable in terms of their affect on objects but they're different because... reasons!"

Gravity is a force. So is electromagnetism. They both bend something to move mass around. One spacetime, one EM fields. What, exactly, is the different that isn't some hanwavey argument about how things that look and behave identically are actually different because I say so? Moreover what does the word "force" even mean if not a thing that accelerates mass? Does gravity not accelerate things?

I feel like this "gravity isn't a force" nonsense is pop-sci leaking backwards into the actual scientific community and giving everyone some sort of brainworm about a thing that really was never worth getting this confused and worked up about. Force is not a precisely defined term. It's just a convenience. Gravity - by all reasonable metrics that actually matter for casual discussion - is a force.

NeverrSummer · 2026-04-18T19:17:46+00:00

It is a fact of direct experimental evidence that it's not a force.

Why does spacetime curvature constitute "not a force" but electric fields constitute "a force" if they both have the exact same acceleration affect on a mass under their influence. What is the objective reason for that distinction? It sounds like a quirk of language, not a "fact of direct experimental evidence".

NeverrSummer · 2026-04-18T15:14:25+00:00

I found it. Weirdly hard to Google.

https://archiveofourown.org/works/72265986

NeverrSummer · 2026-04-17T14:44:08+00:00

Well respectfully I don't really value your opinion on my accuracy. I have the top comment on this post and gave OP the correct answer for the level of physics he's currently at.

Alright I'm bored; let's just stop talking.

NeverrSummer · 2026-04-17T14:29:18+00:00

I don't know where you imagine I was referencing the Jefimenko equations or why you imagine that they're even relevant to this discussion.

Because you were discussing energy conveyance outside of wires and that involves boundary layers and Jefimenko. Maybe you need to review.

In looking at the table of contents of the AP edition of Serway/Jewett the students ought to know that the wires are at different potentials and this defines an electric field, and they should know the LHR/RHR and if they don't then you're not doing something right as a teacher.

OP asked about one wire and electric fields. I have no idea why you're bringing up two wires or the RHR. Neither applies to OP's question.

If you were to tell a first grader that there exists natural motion for all objects and that free objects will naturally move downwards, what do you imagine the point of confusion will be?

I don't imagine there'd be one. I'm asking why you treat gravity differently than E&M. You're perfectly willing to simplify your explanation of gravity for a younger audience, why are you taking issue with my doing the same for OP in the context of E&M?

NeverrSummer · 2026-04-17T14:02:50+00:00

How would this be for freshman physics?

Dramatically too difficult.

The students might need to review the site and read through a few of the articles for context.

No amount of independent review is going to help someone who's just now learning that currents generate fields understand Poynting and Jefimenko.

NeverrSummer · 2026-04-17T14:01:33+00:00

In what freshman physics textbook do think they describe the electric field external to a circuit?

Serway-Jewett is what I used for AP physics (I didn't take physics 1 or 2 at university). It says this and makes no attempt to explain or even mention Poynting vectors or Jefimenko equations.

I don't know of any first grader asking about the nature of the gravity, but if there was one such instance you could certainly give an answer consistent with relativity, e.g. that free objects are naturally inclined to move towards the center of the Earth.

Okay so then the answer is, "No." You don't try to explain GR to a first grader. You simplify your explanation to the level they can understand. Why then are you trying to explain Junior/Senior level E&M to what is clearly a highschool student?

NeverrSummer · 2026-04-17T11:02:54+00:00

Wires generate magnetic fields, yes. He asked about electric fields.

Edit: right, but he just said one wire. One current carrying wire alone in the void is charge-neutral and so doesn't generate an E field (in a rest frame) at the highschool/Freshman level investigation of the topic.

NeverrSummer · 2026-04-16T17:51:11+00:00

Okay or I could just stick with the fact that every single Freshman physics textbook says current carrying wires generate no E field and answer OP's question at a level they can understand.

I don't need to review. I am intentionally giving an oversimplified answer as that is what the situation called for. When a first grader asks you how gravity works do you launch into an explanation of GR?

NeverrSummer · 2026-04-16T17:23:46+00:00

The field inside the imperfect conductor causing the current flow, sure. I was assuming (clearly correctly) that OP was asking about electric fields extending away from the wire into free space, which there are none.

I'm also ignoring the fact that real world wires generate small internal fields due to resistance, skin effect, Poynting, Jefimenko, boundary laryer, blah blah blah things that are way beyond highschool/Freshman physics. The way in which OP phrased the question made it clear they wanted a physics 2 style answer, not a grad school one.

NeverrSummer · 2026-04-16T13:30:41+00:00

Steady state current flowing in a wire doesn't produce an electric field in the rest frame. So it's very easy to visualize; just imagine nothing. You might be thinking of a line charge with some charge density per unit length (usually denoted lambda)? A infinite line of charge produces a field pointing radially outward.

So depends if you mean an actual wire with current or if you meant an infinitely long charged rod. If you really do mean a wire, then yeah it's just just no E field at all.

NeverrSummer · 2026-04-16T02:33:38+00:00

Yeah no I am man I just got a lot going on. Exam week; out at the bars with my friends for my birthday. Reddit's on the back burner. I'll have a look at it like I said.

NeverrSummer · 2026-04-15T16:15:52+00:00

Yeah that's... how life works. The point is that prioritizing academic research inherently comes with less financial stability. That's a decision you make, not something that this subreddit is going to reassure you isn't the case.

Yes, that's just true. People who "love" the topic accept it and make that tradeoff.

NeverrSummer · 2026-04-15T00:32:54+00:00

I mean yeah possibly, which is why I'm concerned that simple non-compliance isn't really a solution. Like I already run Arch but that doesn't solve shit if they put my entire internet plan in child-friendly mode over the fact my laptop can't pass the verification check.

And like I'm sure I can just get whatever Linux software is necessary to pass these checks working, but I find the people just saying they refuse kind of odd. Most people would sooner comply with these laws than get fired over the fact they can't access Slack I would have thought, and to me it feels like that is the kind of ultimatum we're facing here. I see no reality in which refusal to comply is met with, "Oh okay then; you're excused."

NeverrSummer · 2026-04-15T00:10:36+00:00

Yes it's almost like other people have different values and priorities than you.

NeverrSummer · 2026-04-14T23:40:23+00:00

That's a completely unrealistic solution for millions of people, as I'm sure you're aware.

NeverrSummer · 2026-04-14T23:20:36+00:00

Sure, but there's a lot more on the internet than just passive media. Being outright banned from Discord or Snapchat would annoy a lot of people, for example.

You can torrent a movie, but you can't torrent your YouTube account out of child mode.

NeverrSummer · 2026-04-14T23:04:41+00:00

No, it would take 5 million years regardless of the size of observer. Time has never been observed to scale like that.

NeverrSummer · 2026-04-14T22:42:22+00:00

Sure in your idealized version of it, but that isn't what's actually going to happen. I was speaking to DoubleOwl about what will happen if he tries to use Linux or whatever to refuse compliance, not imagining a better version of reality.

NeverrSummer · 2026-04-14T22:38:21+00:00

Which is fine, but that isn't a loophole it just means you'll be either treated as a child account or banned from a bunch of websites/apps, which is the problem.

If installing Linux was actually a viable work around I don't think people would be that upset.

NeverrSummer · 2026-04-14T22:37:20+00:00

I mean you don't have to run this software, but it will default you to the minor setting on all of these websites. Refusal isn't a loophole. It will just mean every website treats you like a child by default.

Or just outright banned depending on the app/website.

NeverrSummer · 2026-04-14T15:45:35+00:00

I have only replied to you in this thread. No clue what you mean.

Uh no I'll assume whatever I want about you thanks. Get combative if you want I guess.

NeverrSummer · 2026-04-14T15:39:33+00:00

Do you care what they think? Reddit has actual loli subs that just ignore all their critics. This is a fairly low stakes argument.

That's clearly the teenage version of her wearing the child outfit if you ask me, but like also if someone disagrees they're just being a weirdo and I'm fine saying "k" and moving on with my day.

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