"Einstein cast gravity not as a force but as the geometric bending of space and time. In a popular analogy, the fabric of space-time is like the flat expanse of a mattress, and a massive object like a star is like a bowling ball sitting on top. The weight of the bowling ball compresses the mattress, forming a dimple — matter tells space-time how to curve.

In this analogy, a planet is like a smaller ball. If it rolls close enough to the bowling ball, its path will be altered by the dimple in the mattress — space-time tells matter how to move."

This analogy is wrong in a way that even people who've studied physics often don't realize.

On an everyday scale like the Earth orbiting the Sun, almost none of that gravitational interaction is from the bending of space. Far beyond 99% (actually, about 99.999999%) of it is from the bending of time.

Could you be more specific? How does bending time cause the Earth to orbit the Sun?

Imagine you are driving in a car coming up parallel to the sun on your left. Time moves a bit faster for you on the left side than the right side. This slight speedup makes your left side traverse space faster than the right side, which causes a slight drift to the left (and also makes you spin).

Now just add massive scale and distances.

How does this cause a point particle to accelerate towards the sun? Must be something about the gradient, but how does the gradient of time cause you to curve towards the sun?

That's a very cool analogy but I might not be understanding something here. Why then do objects that have no light have gravity? If 99% comes from time dilation, why am I stuck to the earth rather than drifting toward light sources?

Light has nothing to do with this.

The point is that mass bends space-time. The amount of bending is dependent on the size of the mass and on the distance from the mass. Even though the Sun is incomparably heavier than the Earth, it is also MUCH farther away from you. So, space-time around the Earth is curved much more towards the center of the Earth than it is towards the center of the Sun. In the mattress analogy, consider a large mattress, with a bowling ball and a car sitting on it. The car will obviously bend the mattress much more, but if you're close to the bowling ball, you'll still fall towards the bowling ball first before both you and it fall towards the car.

So, say you're in an airplane moving directly forward, with the Sun just overhead (and the Earth obviously just below you). The Earth curves spacetime towards it a lot in this area, while the Sun curves it towards itself just a little bit. The overall curvature is such that time still moves more for the bottom of the plane (closer to the Earth) than the top of the plane (closer to the Sun). So, the bottom side moves a little slower than the top side, but the structural integrity of the plane pulls the top side towards the bottom, causing a slight motion towards the Earth - gravity [note that the GP's explanation got the signs a little wrong - time flows slower, not faster, closer to a big mass]. Conversely, if the Earth disappears from the picture and only the Sun remains, now the top part of the plane will move slightly slower, pulling the bottom part towards it, and thus towards the Sun.

One nit: Time moves a bit slower on the sun's side.

Other than that, thank you for a very clear explanation.

If a particle was dropped into the sun’s gravity (not with “horizontal” motion that might cause it to orbit), is it time dilation that causes it to accelerate toward the sun somehow?

I’m going to ask the obvious next question… so if the sun and me in the car are next to each other but stationary, where is the attraction coming from now? As in, time may make the closer side slower, because we’re stationary, there’s no drift etc

If the sun is on my left, doesn’t that mean time moves a bit slower on my left and the slowdown on the left means I’ve traveled less on my left side? Thus I turn left toward the sun.

I believe that is correct.

This was a helpful visualization: https://youtu.be/U_sI9agWmEw?si=MItDfnTx1-oT_qX_

Also very well explained by PBS Spacetime here https://youtu.be/UKxQTvqcpSg

I skimmed the video, but it's definitely the same example that finally made this make sense to me.

I always hated the ball and sheet example simply because it was describing gravity with gravity. It felt fundamentally wrong.

It changes the geodesic that Earth follows, from a straight line (in 3D space) to a curved one (an ellipse).

And also, how does one bend time?

It means clocks tick at different rates depending on where they are.

Imagine spacetime as a field of local clocks. Far from the Sun, clocks tick faster. Near the Sun, clocks tick slower. A freely moving object tries to follow the straightest possible path through spacetime. But because the “time axis” changes from place to place, what counts as “straight ahead into the future” tilts slightly inward near the Sun. So the Earth’s path through spacetime curves toward the Sun.

Earth’s spatial speed around the Sun is about 30 km/s. But through spacetime, its “timeward” motion is basically c, 300,000 km/s. So even a tiny tilt in the time direction creates a significant spatial acceleration. That is why the time-warping term dominates for slow massive bodies.

Does the atmosphere stay attached to the earth due to the bending of time?

That's right -- the atmosphere stays attached to the Earth mostly thanks to gravity, and the Earth's gravity in GR is almost entirely the gradient in clock rate near the Earth.

Near Earth’s surface, clocks lower down tick very slightly slower than clocks higher up. The change in tick rate is on the order of 10^(-16) per meter. While extremely small, that's enough to generate the familiar 9.8 m/s^2 spatial acceleration we experience. Such a small gradient in clock rates generates macrosopically noticeable spatial accelerations because the "translation" factor is c^2, a tremendously large number.

Now, if I wanted to cover all my bases here, I'd need to point out that gravity does also bend space -- that is just not a relevant factor for "ordinary" gravity acting on relatively slow moving matter (like the Earth itself, or the Earth's atmosphere). For instance, for light itself, spatial bending is just as important (in fact, the gravitational deflection of light by a weak static gravitational field is controlled by a near 50/50 split between spatial and temporal effects). Near a massive black hole, it's not that simple and can't meaningfully be understood in terms of "time" and "space" effects being independently separated.

I’ve seen this described before in terms of how GPS is able to do what it does, so not surprising. But still haven’t explained why time would so dominate the space dimension.

It's much simpler than anyone thought:

https://youtu.be/A-2XQQDD6QQ

Same way you bend space. In GR, time is just another dimension of a slightly different flavor.

All objects move through spacetime at the speed of light, but a stationary object is moving in the time direction. (And the time dimension has opposite sign to spatial dimensions, so (Lorentzian) rotation's effect on length works opposite to what you'd expect from Euclidean rotations: https://commons.wikimedia.org/wiki/File:Spacetime_diagram_of....) Suppose we drop a test mass from the top of the leaning tower of Pisa. The "forwards through time" direction takes the object deeper into the local gravity well: as far as the test mass is concerned, it's just moving forwards through time according to Newton's First Law, and everything else is accelerating towards it for no apparent reason.

It may help your intuition to consider the extreme case of a black hole. The event horizon is where time is so warped that no possible future trajectories lead outside of the black hole, and you need a magical time machine to escape. (Of course, the best way to gain intuition is to work through the mathematics, either symbolically or with diagrams, rather than reading English-language descriptions.)

There is a sense in which an orbit is a straight line. Obviously, an orbit is not a straight line through space (unless you count the perfect and unobtainable orbit of a beam of light around a black hole, some distance from the event horizon), but we often think of them as spirals through spacetime: there's an argument that really we should think of them as straight lines through spacetime, much like how a great circle is a straight line along the earth's surface.

Aka the Einstein tensor

i agree with you but i'd go even further

time and gravity are the same thing, the history of understanding physics is basically of the same nature, understanding that two things are actually one thing, which is more like philosophy but with physical confirmation

> a measure of quantumness known as “magic.”

This naming-proposal couldn't possibly cause any problems down the line...

> They had worked out a way of running software on a classical computer that would mimic a quantum task.

When it comes to using a regular computer to mimic (read: fake) the execution of an exotic program/API for nonexistnet future hardware, I highly recommend the humorously titled talk: "Temporally Quaquaversal Virtual Nanomachine Programming In Multiple Topologically Connected Quantum-Relativistic Parallel Timespaces... Made Easy!" [0][1]

[0] https://www.youtube.com/watch?v=HzTjPx4NIiM

[1] https://www.youtube.com/watch?v=ZpInOI4o2LY

To be fair, it isn't that different from why we have imaginary numbers. Or why the reals are calls reals.

Which. Yeah, has been a pretty bad thing for people in understanding those. :(

> This naming-proposal couldn't possibly cause any problems down the line...

You're a little late here, "magic" is already a fairly well known term in quantum computing literature. There's "magic states" and protocols for "magic state distillation" and "magic state injection", there's "shallow magic depth circuits", etc.

I had assumed it was a play on the saying "any sufficiently advanced technology is indistinguishable from magic" but I didn't see that in the article.

Is any of this experimentally testable in the real world?

Would gravity or spacetime under these definitions behave differently and yield something we can observe?

Or is this fancy math modeling that looks nice on paper, but that we won't be able to test until we become a Kardashev type III civilization?

See the end of the article, after further research quantum gravity could be simulated on a quantum computer. The links between research on quantum computing and quantum gravity are fascinating anyway!

Simulating it on a computer, even a "quantum computer", is not the same as testing it against actual reality.

Ah. You're assuming we're not living in a simulation?

As far as I know it’s the latter and that’s a big problem for physics. A lot of stuff like string theory, loop quantum gravity, etc. require energies that would take a particle accelerator the diameter of the solar system or something nuts like that.

Without tests it’s just pretty math that can be coaxed into agreeing with reality but that proves nothing.

Physicists try to indirectly test all the time via cosmological observations but that is extremely hard and limited to what you can infer and how well you can eliminate other explanations or sources of error.

I believe there was a science fiction story all the way back in the early '80s describing a scenario where physics gets reclassified as a soft science or an art form because it is no longer feasible to prove anything.

Does the model need to offer new testable hypothesis if it provides a way of explaining existing results that current models can't?

If it is competing against another model that does both that and offers new testable hypothesis (which experiments match), the other model is the clear winner. But lacking that, if no other model explains all existing data, is new testability really necessary when it is the only model that currently explains all existing tests?

That said, aren't most of theoretical models only contenders for such, as in they haven't been expanded to actually explain all testing results, only that, as far as they have been expanded, there are no contradictions yet? So they need physicists to expand them, but if the model is wrong, the effort might largely be wasted, and we have some models that there is disdain for not because they contradict existing experiments, but because they have eaten too many careers without showing value in return?

Do they though? Are physics textbooks putting forward some version of string theory from the 1990s as proven fact?

> This naming-proposal couldn't possibly cause any problems down the line...

Your worries are a bit late, there's already a huge amount of new age conspiracy bull about quantum healing with wave function collapse, microtubule alignment and biophotons - quality all-you-can-eat word salad buffet.

Don't underestimate the capacity for the problem to get significantly worse.

Blame Roger Penrose for the microtubule bullshit. Ironically, he's the opposite of new age, dude won a Nobel prize.

Maybe, just maybe, an eminent physicist who won the Nobel Prize knows more than us. At the very least his ideas deserve consideration instead of ridicule and dismissal.

Also as far as I know, Penrose’s main argument is that consciousness can not be computational. If you can’t argue against an idea with reason and resort to name calling, you’re not being rational you’re just being dogmatic and censoring ideas.

I didn't say all his theories were garbage, though the theories inspired by them developed by laypeople almost certainly are. I just don't find his argument compelling enough on its face to warrant holding them up as real progress.

Also, remember that Isaac Newton was deep into alchemy and religious prophecy. Just because you have one good idea and you're smart enough to follow it to its logical conclusion doesn't mean every idea you have is good.

Again, if you disagree with Penrose’s idea, just explain your disagreement. It’s so ironic how you’ll call it bullshit and link to some pop culture skeptic idea with no scientific backing to try and undermine an idea in defense of “real science”

> Another approach is to follow that word, heresy. In every period of history, there seem to have been labels that got applied to statements to shoot them down before anyone had a chance to ask if they were true or not. "Blasphemy", "sacrilege", and "heresy" were such labels for a good part of western history, as in more recent times "indecent", "improper", and "unamerican" have been.

https://paulgraham.com/say.html

I'm disagreeing with the notion that someone "who won the Nobel Prize knows more than us". History suggests otherwise.

Surely you must appreciate the irony when your primary argument is an appeal to authority, while on the other hand you dismiss everyone who is unconvinced as "dogmatic".

As for Penrose's specific ideas, i'm not familiar enough with them or the field to make an informed judgement. Hence i would defer to other experts in that field, who as far as i understand are unconvinced. However, the fact he previously won a nobel does not lead me to give him any more credence than i would anyone else. If anything its a negative signal.

That said, if i was going to bite:

> Penrose’s main argument is that consciousness can not be computational. If you can’t argue against an idea with reason

The onus is on Penrose to show consciousness is non-computational. Preferably with some sort of experiment (or are we in the realm of pure philosophy here? Arguing how many angels are dancing on the pin). Science is about creating hypotheses and testing them. Admiteddly im not super well-read on this topic, but i don't think this theory has yielded testable predictions not explainable by other theories that have been verified.

Let he go first and start arguing for this one with reason. If he insists on using discredited ideas that are known not to lead to the results he insists on, name-calling is an appropriated response.

Charm, quark, colors, time crystals, holographs.. And now, magic. Don't worry Einstein, no spooky action at a distance here, it's just magical.

> The more non-Clifford gates you need to produce a quantum state, the more magical that state is. The group found that the particles were highly magical. ..They showed that magic gave space its springiness. Magic, in other words, is connected to space’s ability to bend.

At some point these physicists crossed over into a very specialized form of poetry, a game of language.

You can just call it second stabilizer Rényi entropy or non-stabilizerness if you find "magic" strange and prose is more your flavor than poetry.

Strange quarks[1] are not magic. :)

[1]: https://en.wikipedia.org/wiki/Strange_quark

Actually "non-stabilizerness" does describe it better than "magic".

> In quantum information theory, magic is a property that quantifies the computational resources needed to describe quantum states beyond stabilizer states.

> In 2024–2025, quantum magic was detected in top quark pairs produced at the Large Hadron Collider; it is the first observation of this property in fundamental particle collisions.

https://en.wikipedia.org/wiki/Magic_(quantum_information)

And "second stabilizer Rényi entropy" is even better, it's exactly the kind of technical term I'd prefer, that describes what it means.

> One measure of quantum magic is the stabilizer Rényi entropy of order α such that..

https://en.wikipedia.org/wiki/R%C3%A9nyi_entropy#Stabilizer_...

Is it measured in Thaum? (which, as everyone surely knows by now is the amount of magic needed to create one small white pigeon or three normal-sized billiard balls)

> The thaum is the basic unit of magic. The thaum is made up of so called resons, which are themselves made up of at least five flavours including up, down, sideways, sex appeal and peppermint.

400 billion dollars and a portal to hell later scientists discover evidence of the elusive spearmint.

Time crystals, AFAIK, are actually descriptive: they're crystals in the sense that they produce regularities through occupying the lowest energy state - they just do that in time, not just space.

Don't forget snap, crackle and pop, and quantum teleportation.

Physicists get a failing grade for naming things.

Meanwhile, on HN: "Don't use yarn, use bun it's written in zig!"

You mean post quantum, theoretical physics. Up to 19th and early 20th, physicists somehow knew how to name things. It is possible that the nature of the beast itself has changed and it attracts a different kind of mindsets ...

Color charge and the strange and charm quarks are not post-quantum theoretical physics, are they?

There's also other areas where a current of picking simple names instead of greek/latin terms was popular for a while at least - Shannon named the smallest unit of information a "bit" after all.

That stuff is after Einstein, Heisenberg, and Bohr. When I mentioned quantum mechanics, these are the physicists I had in mind.

Maybe Greek and Latin vocabulary is just overextended at some point? I don’t really see the issue with Snap, Crackle and Pop. The potential confusion around Magic seems much greater, although when you consider the vastly more common opposite effect, where specific scientific terms become popular and quickly gain wholly different colloquial meanings, perhaps it doesn’t really matter in the grand scheme of things.

Perhaps Magic is even so ridiculous that it’s immune to co-option by charlatans. After all, they choose sciency words to lend an air of credibility. OTOH the perceived ridiculousness could also change rather quickly. It’s just the nature of language use…

Should call the next big physics thing doubtscumbagium...

Maybe it is easier to get funding with catchy and/or mysterious names?

Most of the crazy names come from before "quantum" was co-opted by a lot of BS. I don't blame those physicists for naming things that way because the coopting was inevitable. However, we are now decades into that process, and it is inconceivable that the authors choosing the name "magic" are unaware of it. Which means they are doing it with knowledge beforehand, and they should know this is a bad idea.

It's not just a bad idea because of that BS, but even within the field it's just asking for trouble. We may all wish we were perfect Vulcans who have perfect mental separation between all concepts and emotions, but we aren't. It's going to have a small, but extremely persistent and long-term effect on the field if you seriously name a major part of it "magic". The emotional connotations simply can not help but smear into the putatively mathematical term. It's a high price to pay for what isn't really all that funny of a joke even the first time.

And of course the BS will crank up even higher. People get hurt by that, but I don't know how much to lay at the foot of people who are all but taunting them by naming something "magic", because most of the hurt was going to come anyhow and what particular guise it is wearing is of minimal importance. Still, why even sign up to be in the line of fire of responsibility for that sort of thing?

It's older than that. Atoms have neither orbitals, nor shells. Neither describes a probability field at various energy levels surrounding the nucleus.

Analogies aid understanding, even if on an abstract level.

I can sort of appreciate these shenanigans as short-lived common room humor, but I find it obnoxious to put it in the official terminology.

It's bad enough all the corporations trying to steal perfectly active words for their brand names or products.

Ghosts are also a thing in quantum field theory

And slavery, unfortunately. (Slave variables, slave bosons, etc.)

we had "god particle" too …

To be fair, that one came from an editor not a physicist; the physicist wanted to call their book «the goddamn particle», and it got censored/editorialized to «the god particle».

I've heard that story and it doesn't ring true to me. It's not that aggravating to find. Try measuring a neutrino mass, which is still an open problem and looks as if it will remain so for a very long time.

Is that really where the name came from? I remember being struck by how dumb that was and thought “a journalist must have come up with that”.

Greek 'anameixi' loosely means a mixture or a blending. The special states could be called 'anameixic', the property could be called 'anameixicity'.

Why am I trying to find a name for this? Otoh, why are so many physicists trying so hard to popularize their projects for the last 40 or 50 years? Oh .. I think I just answered my own question.

Are you suggesting "anameixi" to replace "magic"?

But magic is related to non-Cliffordness, not mixing.

Also, the term "magic" is pretty well used in quantum computing, it really doesn't need to be popularized. The concept is quite important already and would be talked about regardless of its name.

If you want to learn more about quantum mechanics starting from 1+1=2 please check out https://quantum.chaidhat.com !

That is an incredibly unfortunate term to use for the phenomenon.

I agree, although there is a long tradition of terrible naming in the sciences.

One of the most boring and yet egregious examples imo is "Random Variable". So named because

- they aren't random and

- they aren't variables.[1]

A "random variable" is actually a measurable deterministic function from the set of possible outcomes of some experiment to the real numbers. But you can see why the name "random variable" is confusing to people.

[1] https://cyril9227.github.io/random-variables/ and elsewhere.

> A "random variable" is actually a measurable deterministic function from the set of possible outcomes of some experiment to the real numbers.

I don't think that this was the formalization that was used when the term was coined, given how late set and measure theory were formalized.

They can choose any word to name a new feature; and they choose "magic"... Next one, it'll be "dark magic".

In absolute, those are irrevocably pliable scientific facts.

Quanta article are getting longer and longer. AI effect?

> while these locations can be constricted by these particles

Anyone else get Game of Life vibes?

Whole lotta bike shedding going on in this thread.

I've always considered magnets to be the closest thing we have in real life to magic.

That's exactly why mathematicians should name things.

IMHO, as an analogy, matter is not 'a bowling-ball on a mattress', but more like a scrunched-up section of table-cloth. Tiny knots or whirlpools of space-time/quantum fields, different particles are different topologies of knot, albeit the nature of space-time is unclear and it may well be a projection.

An ant traveling at constant speed on a "scrunched up section of a table cloth" will still take the same amount of time following the same path to get from A to B. Any material analogy requires some kind of stretching or compression.

I agree, the table-cloth is rubber.

It sounds as if it's in the same vein that gave us "strange" and "charm" and "color" (in the strong force sense). There was a whimsical time in particle naming. I'd say it ended when they rejected "truth" and "beauty" in favor of "top" and "bottom".

We can do better than "magic".

They are not "promoting" the term magic. It is a well-known and commonly used term in quantum computing research. It is also pretty well understood as a concept (mathematically), even if it's not always easy to recognize in nature or easy to know when it needs to be used in algorithms.

That's how science always worked. The stupid people throw money at smart people and sometimes they pay back with good things. Any attempts to optimize that is futile, so the best we can do is to continue throwing money.

Unfortunately that is not how it works in capitalist societies, because the smart people will eventually figure out how to siphon the maximum amount of money out of the government regardless of the results. Or do you think we should also keep throwing money at Boeing because there are still a few smart engineers left and we might get a worthwhile Starliner and SLS eventually it we just keep throwing money?

Also, if all you have is a dual model, then it’s equally accurate to say entanglement arises from spacetime. Eg, this article describes entanglement giving rise to wormholes, but the model equally says wormholes give rise to entanglement.

They’re promoting their preferred frame to ontological status when you can’t use a dual model to assert more than equivalence between frames.

Welcome to modern theoretical physics. This stuff has been going on for more than a quarter of a century now. Yes, AdS/CFT was super cool when it first came out. Just like String Theory was. But both have produced nothing that people had originally hoped for. Just endless mathematical intricacies that are further and further removed from our real universe. The best that came out was some mathematical tooling for adjacent fields that had little to do with understanding the fundamental rules of the universe.

> this whole field is starting to feel more like a jobs program for mathematicians out of new ideas.

So sick of seeing phrases like this.

Science is not business. It is not about producing results that you personally think are important. It is understanding the nature of the universe for the sake of it.

> It is not about producing results that you personally think are important. It is understanding the nature of the universe for the sake of it.

Is this actually stated somewhere by the institutions that take taxpayer money for this research, or just your opinion?

If you’re talking about taxpayer money and you’re in the United States, maybe a better starting point is the ‘jobs program’ they’re running for military personnel

Please enlighten us how purely theoretical mathematical constructs, that are impossible to test, help us understand anything about our universe.

Lots of science is impossible to test practically for hundreds of years before it is actually experimentally verified

Imaginary numbers are purely theoretical, but they turn out very helpful in almost every engineering discipline

Imaginary numbers are a helpful tool for calculating things in our universe. All these holographic theories and their insights are based on a universe that behaves basically opposite to ours.

From Wikipedia, imaginary numbers...

> Originally coined in the 17th century by René Descartes[4] as a derogatory term and regarded as fictitious or useless, the concept gained wide acceptance following the work of Leonhard Euler in the 18th century, and Augustin-Louis Cauchy and Carl Friedrich Gauss in the early 19th century.

I think the jury is still out wrt utility of AdS spaces. They could be useless toys, or they could be in the Descartes phase rn.

Science and math are not the same thing, though. The concern is that physics, a science, has been sliding too much into math research - specifically talking about the foundations of particle physics.

That is, the concern is that instead of studying the real world, theoretical physicists are spending more and more time studying mathematical constructs and their properties.

Quanta usually has fairly good articles, but the headlines are often very bad.

Not just the headline. Is it possible to take any scientist talking about something they term as magic seriously?

Would you prefer "non-Cliffordness"?

Does using words that are more of a mouthful make scientist more credible?

> Is it possible to take any scientist talking about something they term as magic seriously?

Obviously. Because the fact that they use this word for something modernly scientific means that its meaning is as far from the commonfolk meaning of the word as possible. Magic doesn't mean anything sensible yet. So it's basically free real estate for something physical, especially something very foundational.