I am not sure what the thought experiment is here — it is more like two facts, one about the Planck scale (and things break there) and the other about a black hole (its information is proportional to its surface).
However, there are deeper things around. Seth Lloyd suggested that we use information density to derive general relativity from quantum theory:
https://arxiv.org/abs/1206.6559
yoaviram 7 hours ago [-]
Not only are these not thought experiments by most definitions, this is also not really an article by most definitions. It's as if the author had a few interesting yet unrelated thoughts, scribbled them down and covered up for the lack of depth with fancy illustrations and transitions.
dentemple 6 hours ago [-]
They're not unrelated thoughts. The author is describing current mysteries in physics related to the edges of what we could theoretically measure.
The article actually seems clear and straightforward to me. I'd only add that I wish there were links at the end regarding what scientists are proposing right now for resolving those mysteries.
lisper 21 hours ago [-]
There is an even simpler thought experiment you can do to reach this conclusion: consider what the result of measuring anything to an infinite precision could possibly look like. It would require somehow recording an infinite amount of information. How would you do that, particularly when you take into account that everything you can interact with to make an information storage device is subject to the Heisenberg uncertainty principle?
JumpCrisscross 21 hours ago [-]
> consider what the result of measuring anything to an infinite precision could possibly look like. It would require somehow recording an infinite amount of information
This is Zeno's dichotomy paradox [1]. Finitely-defined infinitely-complex systems (e.g. fractals and anything chaos theory) are the escape.
There's a much simpler escape: That space is ultimately discrete (i.e. that there's an elementary length) rather than infinitely continuous.
analog31 16 hours ago [-]
The universe runs on IEEE floats. The missing matter and energy are due to roundoff error. We pray to the great NaN in the sky.
defrost 16 hours ago [-]
I'd subscribe to your religion but for the division.
nomel 16 hours ago [-]
Division? Our productorial sect believes the universe does not have such a useless operation. Multiplication by fractions is the true implementation of the NaN one!
defrost 16 hours ago [-]
That sounds a bit shifty.
NoMoreNicksLeft 5 hours ago [-]
I both hate you and am very scared that you're actually telling the truth.
JumpCrisscross 20 hours ago [-]
> a much simpler escape: That space is ultimately discrete (i.e. that there's an elementary length) rather than infinitely continuous
Sure. The point is the gedankenexperiment proves nothing. We don't need to "[record] an infinite amount of information" to encapsulate the infinity between any pair of real numbers.
Maybe we would .. but Musk has to turn off his leaky Starlink over the Murchison (not so) Quiet (anymore) Zone first.
astrange 14 hours ago [-]
We got space telescopes and stuff.
defrost 14 hours ago [-]
More expensive, harder to maintain and keep current, and a tangent to the core matter; Starlink satellites leak radiation and could be shielded, Starlink satellites could be {switched off | turned low} off over Quiet Zones but are not.
Statements were made that shielding would improve after Ver 1.0 .. it got worse. Statements were made that sats would go low power over quiet zones, they do not.
Returning to your erudite point "and stuff"
The NASA Cosmic Background Explorer (COBE) satellite orbited Earth in 1989–1996 ...
Inspired by the COBE results, a series of ground and balloon-based experiments measured cosmic microwave background anisotropies on smaller angular scales ...
The sensitivity of the new experiments improved dramatically, with a reduction in internal noise by three orders of magnitude.
Hmmm, it appears the ground based results were a dramatic improvement over the sat based data.
mensetmanusman 8 hours ago [-]
A moon base with regular travel might make maintenance on the dark side of the moon possible.
defrost 7 hours ago [-]
Sure, when we get there again, can make regular trips, and have consequence free energy to burn that'd be great.
In the interim, and as a general rule for all private entities, it'd be nice to not pollute the commons with unnecessary discharges and sparkles and to carry through on pinky promises to maybe do something about that.
mensetmanusman 5 hours ago [-]
It might be a necessary intermediate for advanced civilizations.
javajosh 12 hours ago [-]
If it were not so you could encode an arbitrary amount of information into the specific length of a one dimensional object. It would be like a physical Taylor series, but since you can go arbitrarily small you can encode arbitrary coefficients. In fact, if you had a physical disc you could encode everything at every point along its circumference. Which is, like, everything squared or something.
adrian_b 9 hours ago [-]
No, this is a wrong argument.
There are a large number of continuous physical quantities, not only length (though all continuous quantities are dependent in one way or another on space or time, which are the primitive continuous quantities), and the reason why you cannot encode an arbitrary amount of information into a specific value of such a quantity is because it is impossible to make an object for which such a quantity would have a perfectly constant value. All the values of such quantities are affected by noise-like variations so you could store information only in the average value of such a quantity, computed over some time and any such average would still be affected by uncertainties that limit the amount of information that can be stored.
One of the most constant lengths that have ever characterized an artificial object has been the length of the international prototype meter kept in France and used to define the meter until 1960. To minimize the length variations, that meter bar was made of platinum-iridium alloy and it was measured at a temperature as constant as possible.
Despite the precautions, which included gentle removing of the dust and handling with soft grippers, the length of that meter bar fluctuated continuously. Even if it was attempted to keep a constant temperature, very small fluctuations in temperature still caused thermal expansions and contractions. Every time the bar was touched, a few metal atoms were removed from it, but other atoms from the environment remained stuck to its surface, changing the length.
All these continuous variations have nothing to do with the possibility of the space being discrete, but they limit the amount of information that can be stored in any such value.
For now there exists absolutely no evidence about the space or time being discrete and not continuous. There have been attempts to make theories based on the discreteness of the space and/or time, but until now they have not provided any useful result.
javajosh 5 hours ago [-]
No, this is a wrong argument. We can specify arbitrarily low temperatures by hypothesis, obviating the objection. If you want to get pedantic you could note that measuring something that is, say, 10^-30m is unphysical - not even laser interferometry gets that small, or anywhere close. However, given that the argument uses a counter-factual, you'd have to extrapolate all the ways that would affect apparatuses.
Instead, my way is simpler by generating an absurd result that if you could build and measure a thing to arbitrary precision you can encode infinite information into it. This is enough for me to reject the counter-factual without going through the messiness of thinking through hypothetical realistic experiments.
The one interesting place to consider is at the Schwarzchild radius of a black hole, where presumably information accumulates to an absurd degree, monotonically over time. I don't really know enough about it to comment intelligently, so I won't except to note its existence.
20 hours ago [-]
s1artibartfast 1 hours ago [-]
Integers have perfect precision, but finite storage. For example, pi is infinite information and digits in float, but finite when represented as a single symbol
Joker_vD 6 hours ago [-]
I think the Pythagoreans had the same silly crisis about square root of two that you have about the real-valued measurements. And the solution, I believe, would be the same: there simply are two physical things with lengths that relate to each other exactly as sqrt(2) to 1.
So, how would result of measuring e.g. length of something to an infinite precision look like? It would look like two particles that are kept at rest relative to each other; the distance between them is the measured distance. Whether this distance has to be commeasurable with the Planck scale or not is an interesting question but it really can go either way.
lisper 56 minutes ago [-]
> two particles that are kept at rest relative to each other
And how do you do that in the face of Heisenberg uncertainty?
enkid 21 hours ago [-]
Just because you can't record something doesn't mean it doesn't exist.
mannykannot 5 hours ago [-]
This brings to mind one of my favorite quotes:
The Schrödinger wave-function is expressed in a unit which is the square root of an inverse cubic meter. This fact alone makes clear that the wave-function is an abstraction, forever hidden from our view. Nobody will ever measure directly the square root of an inverse cubic meter.
Freeman Dyson, Why is Maxwell’s Theory so hard to understand?
Sure but i can invent infinitely many unfalsifiable claims that mean nothing
lisper 21 hours ago [-]
Who said anything about recording? What would the subjective experience of measuring something with infinite precision possibly be like?
JumpCrisscross 20 hours ago [-]
> would require somehow recording an infinite amount of information...
>> Just because you can't record something...
>>> Who said anything about recording?
lisper 19 hours ago [-]
Sorry, my mistake, I was distracted when I wrote that reply. Yes, I did write that, but it's not actually essential to the point I was trying to make, which was: what could the result of measuring anything to an infinite precision possibly look like?
JumpCrisscross 19 hours ago [-]
> what could the result of measuring anything to an infinite precision possibly look like?
Depends on what you're measuring. To illustrate why that isn't a facetious response, consider the difference between 'measuring' pi, 'measuring' a meter and 'measuring' the mass of a proton. (Or, for that matter, the relative mass of three of something to one of it.)
d_tr 15 hours ago [-]
You'd need to somehow record refinements endlessly? I don't get what you're getting at.
lisper 17 hours ago [-]
How do you measure pi?
skirmish 14 hours ago [-]
By repeatedly throwing a needle on a striped pattern: [1]. Obviously, you will need an infinite number of throws for an infinitely precise measurement of pi.
It's worse than that: you also need an unambiguous way of determining whether the needle is overlapping a stripe.
JumpCrisscross 17 hours ago [-]
> How do you measure pi?
Pick your method. It’s the ratio of a circle’s circumference to its diameter.
PeterisP 9 hours ago [-]
You can calculate or 'measure' an arbitrary approximation of that ratio by various methods, but calculating all of it takes infinite time, which I don't have and thus can't do it.
winwang 14 hours ago [-]
Considering that we don't know the value of pi (not that we could write it out nor read it), I'm not sure your definition of "measure" is the same as mine or most people's.
Dylan16807 13 hours ago [-]
I think your definition of "know" is unreasonably strict. Especially because we can write out pieces of algebra that are exactly pi.
I think it's reasonable to say we can't truly measure pi, though.
And you can neither know nor measure a random real.
_cs2017_ 15 hours ago [-]
The article made the wrong statement. The thought experiment isn't that you can't measure length with infinite precision. It's that you can't measure length with precision better than the Planck length. No infinities are involved here.
woopsn 17 hours ago [-]
How does this not break the foundations of quantum theory? For example the Heisenberg uncertainty principle itself implies that the conjugate of a discrete variable must have a continuous spectrum. Thus if there are no continuous variables, there can be no discrete ones either. Either this or we need to throw out one of the variables and call it non-physical/observable -- and yet it very much seems like both position and momentum are things.
drdeca 11 hours ago [-]
The Pontryagin dual of a discrete (locally compact abelian) group is a compact group, and the Pontryagin dual of a compact abelian group is a discrete (locally compact abelian) group…
Hm.
Momentum space being compact does seem weird..
Of course, if rather than a discrete group for space, you just have a discrete uh, co-compact(? Unsure of term. Meaning, there is a finite radius such that the balls of that radius at each of the sites, covers the entire space [edit: “Delone set” is the term I wanted.]), uh,
if you take a Fourier transform of that lattice…
Err… wait, but if the lattice is a subgroup, how does the Fourier transform relate to…
I think the Fourier transform of a Dirac comb is also a Dirac comb (with the spacings being inversely proportional)
If you multiply the Dirac comb by something first…
Well, if you multiply it pointwise by e^(i x p_0 /hbar) , then the Fourier transform will have whole thing shifted by p_0 , and this is periodic in (width of the spacing of the comb in momentum space)
So, if you consider all the pointwise multiples of a Dirac comb in position space (multiplying it by arbitrary functions), then I guess the image of that space under the Fourier transform, is going to in some way correspond to functions on S^1, I guess it would be functions periodic in the width of the comb in momentum space.
So, if instead of a regular comb, you jostle each of the Dirac deltas in the position space comb by a bit first (a different random amount for each)… I’m not sure quite what one would get…
lisper 17 hours ago [-]
> it very much seems like both position and momentum are things.
The operative word being "seems". Position and momentum (and indeed real numbers in general) are mathematical models that predict observations. But the observations themselves are the results of physical interactions that transfer energy, and those can only ever be discrete because energy is quantized.
krastanov 17 hours ago [-]
Energy levels in simple finite systems are indeed quantized, but this does not mean we can not make the energy quanta be continuously parameterized. For instance, if your system is two mirrors facing each other and you are using the quantum description of the light trapped between these mirrors, you can pick any real value for the energy separation between levels of this system simply by continuously varying the distance between the mirrors.
Maybe one can make the argument that position itself is quantized (thus the position of the mirrors can not be varied continuously), but we do not have experimental reasons to believe space is discrete (and quantum mechanics does not require it to be discrete). And while it is pleasing to imagine it discrete (it is more "mathematically elegant"), we do not have any significant rigorous reasons to believe it is.
Edit: Moreover, if you want to describe (in quantum mechanics) the interaction between a finite system and the open environment around it, the only way to get a mathematical description that matches real-world experiments is to have continously parameterized energy levels for the systems making up the open environment. If you assume that only discrete values are possible, you will simply get the wrong result. Most quantum optics textbooks have reasonably good discussion of this. E.g.:
Quantum Optics by Walls and Milburn
Quantum Optics by Scully and Zubairy
Methods in Theoretical Quantum Optics by Barnett and Radmore
lisper 47 minutes ago [-]
> this does not mean we can not make the energy quanta be continuously parameterized
Sure, but can you measure those continuously-parameterized energies? I don't see how.
Continuously parameterized energies are no different from continuously parameterized space. They are part of the mathematical model we use to make accurate predictions, but we have no direct access to either, and (AFAICT) we cannot possibly have access to them because that would violate the no-cloning theorem.
Jorge Borges' way of telling a story as analogy is beautiful and simple.
It takes the resources of the universe to simulate the universe.
oniony 21 hours ago [-]
It would simply be written down on an infinitely long strip of paper.
__MatrixMan__ 20 hours ago [-]
You could use a Turing machine tape for the job. I'm told they're stored in the parentheses mines beneath MIT, somewhere near the point masses.
thfuran 16 hours ago [-]
The shelving down there is frictionless, so they're often not so nearby.
tonetegeatinst 21 hours ago [-]
Möbius strip for double surface area....I can practically see the cheese TV comercial
18 hours ago [-]
A_D_E_P_T 20 hours ago [-]
The Planck Length is a practical limit to the precision you can possibly attain in space.
The electron might be smaller. Its diameter is known to be smaller than 10^-22m, but could be much smaller than that.
Further below the Planck Length, there are strong indications that the universe isn't continuous -- it's discrete. That there's an absolute limit to precision, something really quite analogous to a pixel. This elementary length could be somewhere around 10^-93m.
adrian_b 9 hours ago [-]
The attainable precision is limited to much lower values by much simpler causes.
The theory that the Planck length has any significance is just a speculation.
Nobody knows how interactions would behave at distances so small and there are no known methods that could compress anything into volumes so small. There is no basis to believe that extrapolating the behavior from normal distances and sizes to the scale of the Planck length is valid.
There are pure speculations that are interesting, but in my opinion any speculation about the Planck length is not interesting, because nobody has been able to formulate any prediction based on such a speculation that can be verified in any way.
Most speculations about the Planck length are made by people who obviously know very little about the meaning of the so-called fundamental constants or of about the significance of the useful natural units for physical quantities, to which the Planck length does not belong.
The Planck length is just one way to express the intensity of the gravitational interaction, i.e. an alternative to Newton's constant of gravitation. Its numeric value does not say anything about any other physical phenomena.
The numeric smallness of Planck's length is just an expression of how weak the gravitational interaction is in comparison with the other interactions. It does not have any other significance.
JumpCrisscross 20 hours ago [-]
> there are strong indications that the universe isn't continuous -- it's discrete
There are indications discrete space is plausible. It's actively debated.
There are also strong indications space is continous, e.g. Lorentz symmetry. (This was recently the death knell for a branch of LQG.)
euroderf 9 hours ago [-]
Im my murky conception of reality, the existence of Planck limits indicates that reality is discrete, and that therefore quantum uncertainty must exist.
For example, I pound the picnic table. Presumably this is somehow transmitted thru the entirety of the Earth, or at least thru a tiny portion of it. But is there a cutoff ? Where is the cutoff ? Where is the effect simply too small to "register" in any conception of reality ?
pazimzadeh 20 hours ago [-]
I have similar reasons for not believing that the world that we experience is a computer simulation.
ur-whale 19 hours ago [-]
> It would require somehow recording an infinite amount of information
You're assuming spacetime behaves like the set of reals (something with cardinal ℵ1, if you accept the continuity hypothesis), an object that even if you stay confined within the bounds of pure mathematics, behaves in very, very weird ways.
It may be that spacetime at small scales maps better to a different kind of mathematical object and not even a grid-like one.
rbanffy 5 hours ago [-]
One of my favorites is a different interpretation of the events happening inside a black hole being inscribed in its surface: that there is no inside and the events happen at the surface, which seems totally normal because spacetime is so extremely stretched there things don't realize they look like a 2D surface from outside observers.
kelseyfrog 21 hours ago [-]
I still don't understand why a black holes needs an inside at all. If they are equivalent to their surface then why not dispense with having an interior and just be a surface?
twiceaday 21 hours ago [-]
Why isn't the surface smaller then? Probably something inside is pushing out? It's full? Also on the way to a black hole bodies clearly have insides. Do they somehow evaporate the moment a black hole forms?
Edit: My understanding is that all bodies are the size that they are because the inner/outer pressure equalizes, and this has many equilibriums based on the makeup of the body. Black holes are the ultimate degenerate last-stand where the make up is basically raw "information" which cannot be compressed any further while allowing said information to be recovered, which seems to be a fact of our universe. And it just so happens that the amount of information is proportional to the surface area of the black hole rather than its volume, which is probably a statement about how efficiently information can be compressed in our universe. One dimension is redundant?
enkid 21 hours ago [-]
"Pressure" as a concept doesn't apply to black holes. They are the size they are because of their mass. The bigger the mass, the larger area where their gravity is so great light can't escape. Scientists model black holes as only have a mass and a spin on the inside because that's all the external universe cares about. Information being inscribed on the exterior is an artifact of tike dilating as an object approaches a black hole, iirc.
nvader 21 hours ago [-]
Black holes also have a charge!
enkid 9 hours ago [-]
Yes, that's true, thanks.
naasking 5 hours ago [-]
> Why isn't the surface smaller then? Probably something inside is pushing out?
Hoberman spheres expand and contract via forces that act only along the structures that make up the surface, and this is a simple classical object. I don't see why a more exotic physical object like a black hole couldn't only have properties defined by its surface.
JumpCrisscross 20 hours ago [-]
> Why isn't the surface smaller then? Probably something inside is pushing out?
The surface of space doesn't require something in a higher dimension pushing it out. That such an object may appear to have internal volume from our perspective doesn't need to be any more real than the apparent depth behind a mirror.
crackez 21 hours ago [-]
Since when is the surface of the universe that of a hypersphere?
thebricklayr 21 hours ago [-]
Agreed. Couldn’t black holes warp spacetime to the extent that there is no such place as “inside”? Time dilation is infinite at the event horizon, after all.
As you approach the event horizon, your frame of reference slows asymptotically to match that of the black hole while the universe around you fast-forwards toward heat death. I’d expect the hawking radiation coming out at you to blue shift the closer you got until it was so bright as to be indistinguishable from a white hole. You’d never cross the event horizon; you’d be disintegrated and blasted outward into the distant future as part of that hawking radiation.
WantonQuantum 19 hours ago [-]
The time dilation at the event horizon is infinite for an external observer. It appears that the person falling into the black hole slows down and never passes the event horizon. They redshift until you can't see them anymore.
For the unfortunate person falling into the black hole, there is nothing special about the event horizon. The spacetime they experience is rotated (with respect to the external observer) in such a way that their "future" points toward the black hole.
In a very real sense, for external observers there isn't really an interior of the black hole. That "inside" spacetime is warped so much that it exists more in "the future" than the present.
Professor Brian Cox also says that from a string theory perspective there isn't really an inside of a black hole, it's just missing spacetime. I tried to find a reference for this but I couldn't find one. Perhaps in his book about black holes.
I'm no physicist so happy to be corrected on any of the above!
jiggawatts 12 hours ago [-]
> For the unfortunate person falling into the black hole, there is nothing special about the event horizon.
This is from a simplified model using black holes with infinite lifetime, which is non-physical. Almost all textbook Penrose diagrams use this invalid assumption and shouldn't be relied upon..
Fundamentally, external observers and infalling observers can't disagree on "what happens", just the timing of events. If external observers never see someone falling in, then they didn't fall in.
tsimionescu 8 hours ago [-]
> Fundamentally, external observers and infalling observers can't disagree on "what happens", just the timing of events. If external observers never see someone falling in, then they didn't fall in.
This isn't true. As long as the two observers can't communicate with each other, they absolutely can have different results. To put it in simpler terms, the requirement of physics is that an experiment has a unique result according to some rule, but different experiments can have different results even if they break our intuitions.
So, if you measure the position of a particle falling towards a blackhole, you will see it disappear at the event horizon, and perhaps be radiated out later as Hawking radiation from that same event horizon. If you measure the position of the same particle while you yourself are passing through the event horizon, you will it will record no special interaction and see the particle moving completely normally. Since you can't perform both experiments at once, and you can't relay any data from one to the other, there is no contradiction.
This is just another case of a duality in physics, similar to how some experiments measure electrons as point-like particles completely localized to a certain place, and others measure them as waves spread out over a very large area.
jiggawatts 7 hours ago [-]
> you will see it disappear at the event horizon
I don't believe this is the case -- the particle just becomes ever more redshifted.
tsimionescu 2 hours ago [-]
If that were true, then black holes would appear as extremely bright balls of red-shifted radiation, as all particles whose trajectory ever moved towards the center of the black hole would still be visible. This is obviously not true, black holes appear as completely black objects that might have an extremely bright ring or halo of matter orbiting.
tsunamifury 16 hours ago [-]
You know string theory is now generally considered a large scale fraud perpetrated by cox to maintain funding right?
defrost 16 hours ago [-]
Got a source for either part of that?
* generally considered a large scale fraud,
* perpetrated by (UK's Professor Brian) cox
Most that I know would say that it was disapointingly too big and too general to make specific predictions tied to this specific universe we occupy, although it had early promise.
Brian Cox didn't even make the wikipedia page so its difficult to claim he had any major role in perpertaring it as a large scale fraud.
I am, of course, joking but she posts this sort of easy and empty clickbait.
tsunamifury 15 hours ago [-]
Laughing at someone who says “hey an idea that isn’t falsifiable isn’t a good theory and certainly not something that any other ideas or theories should be constructed upon is I think more serious than not.
bitcharmer 11 hours ago [-]
Yup, her content is not very appealing these days.
lisper 21 hours ago [-]
Because if you free-fall into a black hole you can go past the event horizon.
kelseyfrog 21 hours ago [-]
Can we? Is there a way to test this assumption? If not, then it's not science, right?
mr_toad 18 hours ago [-]
If you free fall into a black hole you are testing it.
I don’t think that not being able to communicate your results makes it not scientific.
malaya_zemlya 16 hours ago [-]
There's a theological doctrine called https://en.wikipedia.org/wiki/Eschatological_verification that claims that statements like "there's God" or "there's afterlife" are perfectly fine verifiable scientific statements, except that their verification come after death or Second Coming.
Your comment reminds me of it.
shpeedy 8 hours ago [-]
Just throw more scientists at the problem.
kelseyfrog 17 hours ago [-]
I think the test involves communicating your results. It's the same thing with the afterlife
amoss 14 hours ago [-]
Publish or perish made manifest.
JumpCrisscross 20 hours ago [-]
> if you free-fall into a black hole you can go past the event horizon
Falling "through" a hologram on the surface would be physically indistinguishable to the person falling from falling into a volume.
20 hours ago [-]
mensetmanusman 8 hours ago [-]
Well stuff started on what seems like the inside, maybe space rips and everything floats to the shell?
21 hours ago [-]
bongodongobob 21 hours ago [-]
A surface implies an interior, otherwise it's a just a point. A surface is a boundary, by definition there is another side, something that is being partitioned.
alanbernstein 16 hours ago [-]
The interior contains a singularity, which may as well be the entirety of the interior. Maybe it has a "degenerate interior", which is very different than a region of space.
naasking 5 hours ago [-]
This is classical, Euclidean thinking and doesn't necessarily apply to exotic objects.
JumpCrisscross 20 hours ago [-]
> surface implies an interior, otherwise it's a just a point
Space-time is not Euclidean geometry under GR.
mr_toad 17 hours ago [-]
But it is continuous, at least until you hit or pass through the singularity.
JumpCrisscross 17 hours ago [-]
> it is continuous
We don’t know this. It has been as far as we’ve measured. But there are compelling reasons to at least consider discrete spacetime.
kelseyfrog 20 hours ago [-]
I'm not a topological expert, but I'm pretty sure you can have a surface without an interior. A unit sphere would be a good example of a surface without an interior.
bongodongobob 20 hours ago [-]
? It by definition has a radius of 1.
krukah 20 hours ago [-]
unit sphere != unit ball
The former is the boundary, the latter is the interior + boundary. One of the great arbitrary naming conventions of math.
magicalhippo 15 hours ago [-]
Minor nitpick, the ball might be closed or open, depending on whether the boundary is included or not, respectively.
hoseja 12 hours ago [-]
Black hole insides is another Penrose universe.
gcanyon 16 hours ago [-]
The observational limits described here remind me very much (albeit that I read it 40 years ago) of Blood Music by Greg Bear. The ending (as I remember it) has nano-scale intelligences observing the universe so closely that the fabric of spacetime starts buckling under the strain.
gibsonf1 5 hours ago [-]
Reality is continuous and always changing. Space-time is just our human way of focusing on aspects of reality to understand it. Space-time is about human perception, not the reality we are trying to understand.
JohnMakin 21 hours ago [-]
Please stop trying to present information in this style of webpage, I am begging you. Besides being an abysmal way to present scientific information, every time someone posts one of these it happens to be a topic I am extraordinarily interested in, but due to disabilities I have, I cannot read it even if I wasn't tremendously annoyed by it.
pmontra 21 hours ago [-]
It's really bad even for me on my phone. The text content fades away before I can scroll it completely into view. No reader mode available.
not_a_bot_4sho 15 hours ago [-]
Same here. I gave up on reading it once the diagram animations made it near impossible
phito 5 hours ago [-]
I closed the page instantly after opening it. Reader view isn't even available. Sigh.
WantonQuantum 19 hours ago [-]
If you're a reader of Quanta, there's nothing new on this page. It seems like a repackaging of some simple concepts in a pretty web format to attract a less sophisticated audience.
23B1 17 hours ago [-]
As a less sophisticated audienc emember, can someone PDF the thing for me my vision wetware can't grok it
wholinator2 20 hours ago [-]
I agree, this is abysmal ux. Doesn't even remotely work on my phone. All those stupid animations literally removing information from my screen before I've had a chance to read it. Drastically reducing the "reading surface" of the actual information attempting to be conveyed. Animations are cool and useful but they too could just be placed on a static page.
The whole thing seems like some over excited marketing person enshittifying the literal idea of static pages of informative just to make something "new".
JohnMakin 4 hours ago [-]
I forget which publication, might have been the new yorker, won a pulitzer prize for a long-form article written in this style. Visually it worked very well (because it was telling a story, not trying to convey information) and the scrolling graphic transitions were gentle enough that I could manage it + reader mode. Since then, it seems like other magazines have followed suit.
empath75 5 hours ago [-]
I don't mind the format, but the article itself was basically nothing you couldn't get from 5 minutes of looking at wikipedia.
selimthegrim 21 hours ago [-]
How could it be made more accessible to you?
oniony 21 hours ago [-]
They could be regular web pages without the silly scroll animations, just like in the good old days.
rmbyrro 19 hours ago [-]
Just make it a web page, not a powerpoint presentation.
JohnMakin 21 hours ago [-]
reader mode supported. sometimes they are sometimes no.
smolder 11 hours ago [-]
I was disappointed to see reader mode wasn't available, and tried to find some other plugin to just show me the text. The couple plugins I tried could not parse it, nor could the text-only browser I downloaded called ViolonCello. (It only renders header and footer text.) It's very frustrating.
mopenstein 20 hours ago [-]
I liked the presentation and it worked great on my phone.
I'm sorry you have issues but I'm glad the world doesn't cater to a single individual's issue.
I can't swim because of a whole in my ear drum from when the Nun at the free clinic my poor mother took me to popped that bad boy with a enthusiastic squeeze from an ear syringe and my tinnitus rings like a son-of-a-bitch when I wear ear plugs but I don't demand they fill in every swimming pool with concrete. I just walk by on those hot summer days wistfully jealous of the guy doing a cannonball and the lady doing the hand stand thing where your feet are in dry air but your head is 2 feet below the water level.
rmbyrro 19 hours ago [-]
The analogy would be more like a library forcing everyone to swim through a pool in order to read a particular book. And if you complain you have a disability, someone says that the world shouldn't cater to an individual.
The analogy is ridiculous, yes. As it is ridiculous to build such a website that disabled people cannot possibly read. You don't have to make it perfect for them, just don't make it impossible.
unethical_ban 3 hours ago [-]
The analogy is to stop making documentary films because one cannot see or hear.
Should businesses and academia strive to make information accessible? Yes. Should every piece of information be put into accessible formats, damn the art? I don't think so.
JohnMakin 4 hours ago [-]
This is an insanely weird and ableist post.
the_gipsy 20 hours ago [-]
You're a moron if you believe these two things compare even remotely
AIorNot 20 hours ago [-]
Besides the silly, but inevitable HN complaints about the format of the webpage presentation, (great presentation btw)
The fundamental challenges these experiments (and others) surface is a deep challenge to the traditional narratives of Materialism or 'Physicalism' as our understanding of what existence is. In essence science and human knowledge has lept forward technologigcally over the past 400 and esp the past 100 years because we started assuming the world was physical in nature, material and metaphysically, ie that it reduced to fundamentally physical things we could quantify and measure.
Yet, the older I get the more inclined I am to believe in some form of Idealism.. Not only in Idealism but I'm leaning towards the belief that some kind of fundamental universal Consciousness is the only fundamental property or baseline to the universe or to existence.
Time and Space is not fundamental. Locality isnt true.
johnsanders 20 hours ago [-]
I remember as a kid asking how many possible speeds there are between 60 mph and 0 mph. Infinite right? So how does the car get from 60 to stopped when mom hits the brakes?
JumpCrisscross 20 hours ago [-]
> how does the car get from 60 to stopped when mom hits the brakes?
That you can split any finite length into an infinite amount does not equate to having to traverse infinite numbers.
cloudking 6 hours ago [-]
The car (and people) never truly stop moving, the earth is in orbit, spinning and rotating around the galaxy.
wzyoi 20 hours ago [-]
Not infinite if we take into the account that we have a physical car. Speed many but not infinite steps.
Everything is infinite if we think this way.
transfire 20 hours ago [-]
Zeno’s paradox.
mensetmanusman 8 hours ago [-]
In the same way a single second occurs.
19 hours ago [-]
DiscourseFan 20 hours ago [-]
I’ve said this so many times now. Contemporary physics would greatly benefit from reading Kant. The extent of his influence on contemporary physics, especially with regard to space and time, is so great and the knowledge of his work so little in the scientific community of today. Almost all the great physicists of the 20th century were familiar with Kantian philosophy and were heavily informed by it.
JumpCrisscross 20 hours ago [-]
What would Kant add to this discussion that the physicists in the article haven't considered?
(Saying this as someone who's read Kant twice and agrees with most of what he claimed. Outside his taste in music.)
DiscourseFan 16 hours ago [-]
>Saying this as someone who's read Kant twice
I assume you mean the Critique of Pure Reason? Kant's Oeuvre is quite vast, though it wouldn't be unreasonable to have read the 3 critiques twice.
>What would Kant add to this discussion that the physicists in the article haven't considered?
Kant himself, I'm not sure, but its his model of the cosmos that we employ today, and spatio-temporality is a development out of his critical philosophy, especially his aesthetics. If you want to break space and time out of spatiotemporality it helps if you are familiar with the metaphysical undergirding of contemporary physics, since we have not treated them as separate since Einstein, even though Kant originally kept them as completely separate intuitions and did not seek to unify them but only to try and see what happens when they are set in relation. That is to say that spatiotemporality is, if we are being good Kantians, an entirely negative, transcendental view of space and time since it does not appear at the level of the senses but rather as an abstraction from them. But if we treat the second-level abstraction as real then we are bound to make errors about the empirical world, as returning to the critical project would, I believe, greatly help in re-evaluating our empirical methods.
JumpCrisscross 10 hours ago [-]
English and German, hence twice.
To be clear, you're suggesting that physisticsts reject general relativity's unification of spacetime because Kant, who obviously had no knowledge of GR nor the empiricism that supports it, did not unify them? Kant's Prize essay also pre-dates e.g. Gödel. That doesn't mean every modern mathemetician must first consider a Kantian slant to their work before rejecting it for well-established and obvious reasons. (Nor that Gödel disproves Kant.)
Deducing that Kant would want us to reject modern science because it's not based on our senses ignores entirely his work as a mathemetician. Kant was, in his own time, a modernist. Not a proto flat earther.
DiscourseFan 2 hours ago [-]
> To be clear, you're suggesting that physisticsts reject general relativity's unification of spacetime because Kant, who obviously had no knowledge of GR nor the empiricism that supports it, did not unify them?
I am suggesting that if someone wants to escape from the current paradigm of physics it may help to understand how it came about instead of wasting a lot of time speculating about what space and time “actually” mean.
And in any case, there is nothing in math that prevents someone from being a flat-earther. If nothing else, set theory and qauntam mechanics has done nothing but flatten our empirical world. Kant was Modern but his work was not, one can read his Opus Postumum as an attempt to reconcile his physics with an intuition that would be capable of bringing about the “feeling of life” that arrives from the experience of natural beauty—which, while very odd, clearly follows from the 3rd critique and the critical project more broadly, unless you throw out the concept of Freedom entirely and all the moral philosophy that follows from it and stay, as some have, in the analytic. But that’s clearly not what Einstein did, Einstein is a Schopenhaurian, he based GR heavily in the Aesthetic, but an Aesthetic devoid of this possible “third” intuition, that of feeling of form, since spatiotemporality annihilates all other possibilities of dimensionality besides space and time. Now what I’m saying is, its not possible for contemporary physicists to critically interrogate their theories without having a solid intellectual grounding in how they came about. Doesn’t mean that someone couldn’t simply come up with something new and brilliant spontaneously, but not by questioning spatiotemporality itself but by developing an entirely new framework that disregards it.
But that’s much more difficult than starting with the basics, right?
23B1 17 hours ago [-]
I too am wanting to know the answer to this question, sounds like an intriguing concept!
ur-whale 19 hours ago [-]
The (what very much feels like an) assertion that "If a collision concentrates enough energy in a small enough region, the particles form a black hole" seems very much rabbit out of a hat.
That supposes in particular that general relativity is still a valid theory at these minuscule scales, something that I believe has never been experimentally verified.
If general relativity's equations do not work at the planck scale, we know strictly nothing about black hole formation.
m3kw9 6 hours ago [-]
Plank length is our physical limit, a humans. Maybe another species smarter than us can prove deeper via some higher dimensions, exotic physics
hoseja 12 hours ago [-]
>If a collision concentrates enough energy in a small enough region, the particles form a black hole and never reach a detector.
Is this actually experimentally confirmed?
simne 9 hours ago [-]
Fortunately or not, largest artificial accelerators are still not powerful enough to produce artificial black hole.
Sometimes from deep Universe, appear particles with much more energy than achieved at labs, and some theories say, their energy enough to create BH, but have not confirmation with decades observations, may be because scientific method need tens or better hundreds appearances in one place to confirm, but have less than half dozen.
naasking 5 hours ago [-]
To the extent that black holes are confirmed, sure.
nyc111 19 hours ago [-]
But physicists already made spacetime redundant by dividing it back to space and time. This was started by Dirac who restated general relativity with Hamilton formalism. The slicing of spacetime was completed in the sixties with ADM formulation. Also we know spacetime does not exist in practice because when we say "universe is expanding" we mean "space is expanding." It makes no sense to say spacetime is expanding.
raattgift 3 hours ago [-]
Your comment is divorced from the coordinate freedom of general relativity.
In any spacetime you care to do an ADM split on, there are an infinite number of real-valued smooth scalar fields whose gradient is everywhere non-zero and timelike available to serve as the coordinate time.
In the standard cosmology the at-rest isotropic and homogeneous distribution of matter provides an obvious coordinate time function, but physics still has to work for other inertial and accelerated observers, so there is nothing preventing anyone from using a non-comoving observer's proper time in the ADM split.
Nits:
* Hamiltonian formulation of general relativity
* ADM formalism
The expansion is in the metric, and most visible (and most amenable to interpretation as an expansion of space) when using comoving coordinates. However, we are allowed to work in any system of coordinates, and when we do a general coordinate transform, we lose the interpretation of the metric expansion as an expansion in space.
("We see in both [Milne & de Sitter] cosmologies that the interpretation of redshift as an expansion of space is dependent upon the coordinates one chooses to calculate z." -- https://academic.oup.com/mnras/article/422/2/1418/1036317 final sentence in §3.4 de Sitter space).
The standard cosmology's FLRW spacetime (and also de Sitter space, where the vacuum constant positive scalar curvature makes for an easier-to-understand expansion history) is time-orientable. There are more points in spacetime in the future direction from an arbitrary point anywhere in the entire spacetime, than in that point's past.
However, the real distribution of matter is in our universe lumpy, as is easily demonstrated right here on Earth. Standing on the ground you can tell that locally there is neither isotropy nor homogenity (you can see quite far up into the sky, but not so far into the ground). Moreover, there are differences in isotropic pressure, convection, heat conduction, and shear stresses between the air and ground, none of which are features of the perfect fluids in the FLRW model. So locally the FLRW metric is not suitable, and since the Earth is very much not vacuum de Sitter is even less suitable. Consequently it should not offend anyone to read that Manhattan isn't undergoing cosmological expansion. Most things within ten kiloparsecs of here are gravitationally collapsing. It requires coordinate contortions to interpret interplanetary or interstellar space in the Milky way as expanding, and switching to different systems of coordinates will blow up that interpretation.
A "swiss cheese" universe with collapsing vacuoles in an expanding cosmology reflects that it's only when we go from ~kpc length scales to ~Gpc length scales that the distribution of matter behaves enough like perfect fluids to allow for an exact solution to the Friedmann equations. The collapsing vacuoles are usually modelled like Lemaître-Tolman-Bondi with a thin shell boundary; this results in a vacuole that time-orientable and has fewer spacetime points in the future direction. "Hole" time functions and "cheese" time functions must be different (hole clocks tick slower as they fall towards the centre).
tsunamifury 16 hours ago [-]
Ah yes a debate between scientists with theories which are so far removed from Science that it can’t be called anything other than fairy tails
For those who aren’t in the know physics is in a crisis where huge portions of theoretical physics are turning out to be complete nonsense.
5 hours ago [-]
gcanyon 16 hours ago [-]
Good lord that was awful to read. Text popped into existence half-off the screen, disappeared just as it was entering the screen, etc. I'm operating on a 15" MacBook with a reasonable-sized window, and yet I had to scroll carefully back and forth to catch the text. And no reader mode with just the text.
dang 15 hours ago [-]
"Please don't complain about tangential annoyances—e.g. article or website formats, name collisions, or back-button breakage. They're too common to be interesting."
However, there are deeper things around. Seth Lloyd suggested that we use information density to derive general relativity from quantum theory: https://arxiv.org/abs/1206.6559
The article actually seems clear and straightforward to me. I'd only add that I wish there were links at the end regarding what scientists are proposing right now for resolving those mysteries.
This is Zeno's dichotomy paradox [1]. Finitely-defined infinitely-complex systems (e.g. fractals and anything chaos theory) are the escape.
[1] https://en.wikipedia.org/wiki/Zeno%27s_paradoxes#Dichotomy_p...
Sure. The point is the gedankenexperiment proves nothing. We don't need to "[record] an infinite amount of information" to encapsulate the infinity between any pair of real numbers.
[0] https://www.physicsforums.com/insights/hand-wavy-discussion-...
A Noether Theorem for discrete Covariant Mechanics, https://arxiv.org/abs/1902.08997
Statements were made that shielding would improve after Ver 1.0 .. it got worse. Statements were made that sats would go low power over quiet zones, they do not.
Returning to your erudite point "and stuff"
~ https://en.wikipedia.org/wiki/Cosmic_microwave_backgroundHmmm, it appears the ground based results were a dramatic improvement over the sat based data.
In the interim, and as a general rule for all private entities, it'd be nice to not pollute the commons with unnecessary discharges and sparkles and to carry through on pinky promises to maybe do something about that.
There are a large number of continuous physical quantities, not only length (though all continuous quantities are dependent in one way or another on space or time, which are the primitive continuous quantities), and the reason why you cannot encode an arbitrary amount of information into a specific value of such a quantity is because it is impossible to make an object for which such a quantity would have a perfectly constant value. All the values of such quantities are affected by noise-like variations so you could store information only in the average value of such a quantity, computed over some time and any such average would still be affected by uncertainties that limit the amount of information that can be stored.
One of the most constant lengths that have ever characterized an artificial object has been the length of the international prototype meter kept in France and used to define the meter until 1960. To minimize the length variations, that meter bar was made of platinum-iridium alloy and it was measured at a temperature as constant as possible.
Despite the precautions, which included gentle removing of the dust and handling with soft grippers, the length of that meter bar fluctuated continuously. Even if it was attempted to keep a constant temperature, very small fluctuations in temperature still caused thermal expansions and contractions. Every time the bar was touched, a few metal atoms were removed from it, but other atoms from the environment remained stuck to its surface, changing the length.
All these continuous variations have nothing to do with the possibility of the space being discrete, but they limit the amount of information that can be stored in any such value.
For now there exists absolutely no evidence about the space or time being discrete and not continuous. There have been attempts to make theories based on the discreteness of the space and/or time, but until now they have not provided any useful result.
Instead, my way is simpler by generating an absurd result that if you could build and measure a thing to arbitrary precision you can encode infinite information into it. This is enough for me to reject the counter-factual without going through the messiness of thinking through hypothetical realistic experiments.
The one interesting place to consider is at the Schwarzchild radius of a black hole, where presumably information accumulates to an absurd degree, monotonically over time. I don't really know enough about it to comment intelligently, so I won't except to note its existence.
So, how would result of measuring e.g. length of something to an infinite precision look like? It would look like two particles that are kept at rest relative to each other; the distance between them is the measured distance. Whether this distance has to be commeasurable with the Planck scale or not is an interesting question but it really can go either way.
And how do you do that in the face of Heisenberg uncertainty?
The Schrödinger wave-function is expressed in a unit which is the square root of an inverse cubic meter. This fact alone makes clear that the wave-function is an abstraction, forever hidden from our view. Nobody will ever measure directly the square root of an inverse cubic meter.
Freeman Dyson, Why is Maxwell’s Theory so hard to understand?
https://www.clerkmaxwellfoundation.org/DysonFreemanArticle.p...
>> Just because you can't record something...
>>> Who said anything about recording?
Depends on what you're measuring. To illustrate why that isn't a facetious response, consider the difference between 'measuring' pi, 'measuring' a meter and 'measuring' the mass of a proton. (Or, for that matter, the relative mass of three of something to one of it.)
[1] https://en.wikipedia.org/wiki/Buffon%27s_needle_problem
It's worse than that: you also need an unambiguous way of determining whether the needle is overlapping a stripe.
Pick your method. It’s the ratio of a circle’s circumference to its diameter.
I think it's reasonable to say we can't truly measure pi, though.
And you can neither know nor measure a random real.
Hm.
Momentum space being compact does seem weird..
Of course, if rather than a discrete group for space, you just have a discrete uh, co-compact(? Unsure of term. Meaning, there is a finite radius such that the balls of that radius at each of the sites, covers the entire space [edit: “Delone set” is the term I wanted.]), uh, if you take a Fourier transform of that lattice…
Err… wait, but if the lattice is a subgroup, how does the Fourier transform relate to…
I think the Fourier transform of a Dirac comb is also a Dirac comb (with the spacings being inversely proportional) If you multiply the Dirac comb by something first… Well, if you multiply it pointwise by e^(i x p_0 /hbar) , then the Fourier transform will have whole thing shifted by p_0 , and this is periodic in (width of the spacing of the comb in momentum space)
So, if you consider all the pointwise multiples of a Dirac comb in position space (multiplying it by arbitrary functions), then I guess the image of that space under the Fourier transform, is going to in some way correspond to functions on S^1, I guess it would be functions periodic in the width of the comb in momentum space.
So, if instead of a regular comb, you jostle each of the Dirac deltas in the position space comb by a bit first (a different random amount for each)… I’m not sure quite what one would get…
The operative word being "seems". Position and momentum (and indeed real numbers in general) are mathematical models that predict observations. But the observations themselves are the results of physical interactions that transfer energy, and those can only ever be discrete because energy is quantized.
Maybe one can make the argument that position itself is quantized (thus the position of the mirrors can not be varied continuously), but we do not have experimental reasons to believe space is discrete (and quantum mechanics does not require it to be discrete). And while it is pleasing to imagine it discrete (it is more "mathematically elegant"), we do not have any significant rigorous reasons to believe it is.
Edit: Moreover, if you want to describe (in quantum mechanics) the interaction between a finite system and the open environment around it, the only way to get a mathematical description that matches real-world experiments is to have continously parameterized energy levels for the systems making up the open environment. If you assume that only discrete values are possible, you will simply get the wrong result. Most quantum optics textbooks have reasonably good discussion of this. E.g.:
Sure, but can you measure those continuously-parameterized energies? I don't see how.
Continuously parameterized energies are no different from continuously parameterized space. They are part of the mathematical model we use to make accurate predictions, but we have no direct access to either, and (AFAICT) we cannot possibly have access to them because that would violate the no-cloning theorem.
Jorge Borges' way of telling a story as analogy is beautiful and simple.
It takes the resources of the universe to simulate the universe.
The electron might be smaller. Its diameter is known to be smaller than 10^-22m, but could be much smaller than that.
Further below the Planck Length, there are strong indications that the universe isn't continuous -- it's discrete. That there's an absolute limit to precision, something really quite analogous to a pixel. This elementary length could be somewhere around 10^-93m.
The theory that the Planck length has any significance is just a speculation.
Nobody knows how interactions would behave at distances so small and there are no known methods that could compress anything into volumes so small. There is no basis to believe that extrapolating the behavior from normal distances and sizes to the scale of the Planck length is valid.
There are pure speculations that are interesting, but in my opinion any speculation about the Planck length is not interesting, because nobody has been able to formulate any prediction based on such a speculation that can be verified in any way.
Most speculations about the Planck length are made by people who obviously know very little about the meaning of the so-called fundamental constants or of about the significance of the useful natural units for physical quantities, to which the Planck length does not belong.
The Planck length is just one way to express the intensity of the gravitational interaction, i.e. an alternative to Newton's constant of gravitation. Its numeric value does not say anything about any other physical phenomena.
The numeric smallness of Planck's length is just an expression of how weak the gravitational interaction is in comparison with the other interactions. It does not have any other significance.
There are indications discrete space is plausible. It's actively debated.
There are also strong indications space is continous, e.g. Lorentz symmetry. (This was recently the death knell for a branch of LQG.)
For example, I pound the picnic table. Presumably this is somehow transmitted thru the entirety of the Earth, or at least thru a tiny portion of it. But is there a cutoff ? Where is the cutoff ? Where is the effect simply too small to "register" in any conception of reality ?
You're assuming spacetime behaves like the set of reals (something with cardinal ℵ1, if you accept the continuity hypothesis), an object that even if you stay confined within the bounds of pure mathematics, behaves in very, very weird ways.
It may be that spacetime at small scales maps better to a different kind of mathematical object and not even a grid-like one.
Edit: My understanding is that all bodies are the size that they are because the inner/outer pressure equalizes, and this has many equilibriums based on the makeup of the body. Black holes are the ultimate degenerate last-stand where the make up is basically raw "information" which cannot be compressed any further while allowing said information to be recovered, which seems to be a fact of our universe. And it just so happens that the amount of information is proportional to the surface area of the black hole rather than its volume, which is probably a statement about how efficiently information can be compressed in our universe. One dimension is redundant?
Hoberman spheres expand and contract via forces that act only along the structures that make up the surface, and this is a simple classical object. I don't see why a more exotic physical object like a black hole couldn't only have properties defined by its surface.
The surface of space doesn't require something in a higher dimension pushing it out. That such an object may appear to have internal volume from our perspective doesn't need to be any more real than the apparent depth behind a mirror.
As you approach the event horizon, your frame of reference slows asymptotically to match that of the black hole while the universe around you fast-forwards toward heat death. I’d expect the hawking radiation coming out at you to blue shift the closer you got until it was so bright as to be indistinguishable from a white hole. You’d never cross the event horizon; you’d be disintegrated and blasted outward into the distant future as part of that hawking radiation.
For the unfortunate person falling into the black hole, there is nothing special about the event horizon. The spacetime they experience is rotated (with respect to the external observer) in such a way that their "future" points toward the black hole.
In a very real sense, for external observers there isn't really an interior of the black hole. That "inside" spacetime is warped so much that it exists more in "the future" than the present.
Professor Brian Cox also says that from a string theory perspective there isn't really an inside of a black hole, it's just missing spacetime. I tried to find a reference for this but I couldn't find one. Perhaps in his book about black holes.
I'm no physicist so happy to be corrected on any of the above!
This is from a simplified model using black holes with infinite lifetime, which is non-physical. Almost all textbook Penrose diagrams use this invalid assumption and shouldn't be relied upon..
Fundamentally, external observers and infalling observers can't disagree on "what happens", just the timing of events. If external observers never see someone falling in, then they didn't fall in.
This isn't true. As long as the two observers can't communicate with each other, they absolutely can have different results. To put it in simpler terms, the requirement of physics is that an experiment has a unique result according to some rule, but different experiments can have different results even if they break our intuitions.
So, if you measure the position of a particle falling towards a blackhole, you will see it disappear at the event horizon, and perhaps be radiated out later as Hawking radiation from that same event horizon. If you measure the position of the same particle while you yourself are passing through the event horizon, you will it will record no special interaction and see the particle moving completely normally. Since you can't perform both experiments at once, and you can't relay any data from one to the other, there is no contradiction.
This is just another case of a duality in physics, similar to how some experiments measure electrons as point-like particles completely localized to a certain place, and others measure them as waves spread out over a very large area.
I don't believe this is the case -- the particle just becomes ever more redshifted.
* generally considered a large scale fraud,
* perpetrated by (UK's Professor Brian) cox
Most that I know would say that it was disapointingly too big and too general to make specific predictions tied to this specific universe we occupy, although it had early promise.
Brian Cox didn't even make the wikipedia page so its difficult to claim he had any major role in perpertaring it as a large scale fraud.
https://en.wikipedia.org/wiki/String_theory
I am, of course, joking but she posts this sort of easy and empty clickbait.
I don’t think that not being able to communicate your results makes it not scientific.
Falling "through" a hologram on the surface would be physically indistinguishable to the person falling from falling into a volume.
Space-time is not Euclidean geometry under GR.
We don’t know this. It has been as far as we’ve measured. But there are compelling reasons to at least consider discrete spacetime.
The former is the boundary, the latter is the interior + boundary. One of the great arbitrary naming conventions of math.
The whole thing seems like some over excited marketing person enshittifying the literal idea of static pages of informative just to make something "new".
I'm sorry you have issues but I'm glad the world doesn't cater to a single individual's issue.
I can't swim because of a whole in my ear drum from when the Nun at the free clinic my poor mother took me to popped that bad boy with a enthusiastic squeeze from an ear syringe and my tinnitus rings like a son-of-a-bitch when I wear ear plugs but I don't demand they fill in every swimming pool with concrete. I just walk by on those hot summer days wistfully jealous of the guy doing a cannonball and the lady doing the hand stand thing where your feet are in dry air but your head is 2 feet below the water level.
The analogy is ridiculous, yes. As it is ridiculous to build such a website that disabled people cannot possibly read. You don't have to make it perfect for them, just don't make it impossible.
Should businesses and academia strive to make information accessible? Yes. Should every piece of information be put into accessible formats, damn the art? I don't think so.
The fundamental challenges these experiments (and others) surface is a deep challenge to the traditional narratives of Materialism or 'Physicalism' as our understanding of what existence is. In essence science and human knowledge has lept forward technologigcally over the past 400 and esp the past 100 years because we started assuming the world was physical in nature, material and metaphysically, ie that it reduced to fundamentally physical things we could quantify and measure.
Yet, the older I get the more inclined I am to believe in some form of Idealism.. Not only in Idealism but I'm leaning towards the belief that some kind of fundamental universal Consciousness is the only fundamental property or baseline to the universe or to existence.
Time and Space is not fundamental. Locality isnt true.
The sum of an infinite series can be finite [1].
[1] https://www.mathcentre.ac.uk/resources/uploaded/mc-ty-conver...
Everything is infinite if we think this way.
(Saying this as someone who's read Kant twice and agrees with most of what he claimed. Outside his taste in music.)
I assume you mean the Critique of Pure Reason? Kant's Oeuvre is quite vast, though it wouldn't be unreasonable to have read the 3 critiques twice.
>What would Kant add to this discussion that the physicists in the article haven't considered?
Kant himself, I'm not sure, but its his model of the cosmos that we employ today, and spatio-temporality is a development out of his critical philosophy, especially his aesthetics. If you want to break space and time out of spatiotemporality it helps if you are familiar with the metaphysical undergirding of contemporary physics, since we have not treated them as separate since Einstein, even though Kant originally kept them as completely separate intuitions and did not seek to unify them but only to try and see what happens when they are set in relation. That is to say that spatiotemporality is, if we are being good Kantians, an entirely negative, transcendental view of space and time since it does not appear at the level of the senses but rather as an abstraction from them. But if we treat the second-level abstraction as real then we are bound to make errors about the empirical world, as returning to the critical project would, I believe, greatly help in re-evaluating our empirical methods.
To be clear, you're suggesting that physisticsts reject general relativity's unification of spacetime because Kant, who obviously had no knowledge of GR nor the empiricism that supports it, did not unify them? Kant's Prize essay also pre-dates e.g. Gödel. That doesn't mean every modern mathemetician must first consider a Kantian slant to their work before rejecting it for well-established and obvious reasons. (Nor that Gödel disproves Kant.)
Deducing that Kant would want us to reject modern science because it's not based on our senses ignores entirely his work as a mathemetician. Kant was, in his own time, a modernist. Not a proto flat earther.
I am suggesting that if someone wants to escape from the current paradigm of physics it may help to understand how it came about instead of wasting a lot of time speculating about what space and time “actually” mean.
And in any case, there is nothing in math that prevents someone from being a flat-earther. If nothing else, set theory and qauntam mechanics has done nothing but flatten our empirical world. Kant was Modern but his work was not, one can read his Opus Postumum as an attempt to reconcile his physics with an intuition that would be capable of bringing about the “feeling of life” that arrives from the experience of natural beauty—which, while very odd, clearly follows from the 3rd critique and the critical project more broadly, unless you throw out the concept of Freedom entirely and all the moral philosophy that follows from it and stay, as some have, in the analytic. But that’s clearly not what Einstein did, Einstein is a Schopenhaurian, he based GR heavily in the Aesthetic, but an Aesthetic devoid of this possible “third” intuition, that of feeling of form, since spatiotemporality annihilates all other possibilities of dimensionality besides space and time. Now what I’m saying is, its not possible for contemporary physicists to critically interrogate their theories without having a solid intellectual grounding in how they came about. Doesn’t mean that someone couldn’t simply come up with something new and brilliant spontaneously, but not by questioning spatiotemporality itself but by developing an entirely new framework that disregards it.
But that’s much more difficult than starting with the basics, right?
That supposes in particular that general relativity is still a valid theory at these minuscule scales, something that I believe has never been experimentally verified.
If general relativity's equations do not work at the planck scale, we know strictly nothing about black hole formation.
Is this actually experimentally confirmed?
Sometimes from deep Universe, appear particles with much more energy than achieved at labs, and some theories say, their energy enough to create BH, but have not confirmation with decades observations, may be because scientific method need tens or better hundreds appearances in one place to confirm, but have less than half dozen.
In any spacetime you care to do an ADM split on, there are an infinite number of real-valued smooth scalar fields whose gradient is everywhere non-zero and timelike available to serve as the coordinate time.
In the standard cosmology the at-rest isotropic and homogeneous distribution of matter provides an obvious coordinate time function, but physics still has to work for other inertial and accelerated observers, so there is nothing preventing anyone from using a non-comoving observer's proper time in the ADM split.
Nits:
* Hamiltonian formulation of general relativity
* ADM formalism
The expansion is in the metric, and most visible (and most amenable to interpretation as an expansion of space) when using comoving coordinates. However, we are allowed to work in any system of coordinates, and when we do a general coordinate transform, we lose the interpretation of the metric expansion as an expansion in space.
("We see in both [Milne & de Sitter] cosmologies that the interpretation of redshift as an expansion of space is dependent upon the coordinates one chooses to calculate z." -- https://academic.oup.com/mnras/article/422/2/1418/1036317 final sentence in §3.4 de Sitter space).
The standard cosmology's FLRW spacetime (and also de Sitter space, where the vacuum constant positive scalar curvature makes for an easier-to-understand expansion history) is time-orientable. There are more points in spacetime in the future direction from an arbitrary point anywhere in the entire spacetime, than in that point's past.
However, the real distribution of matter is in our universe lumpy, as is easily demonstrated right here on Earth. Standing on the ground you can tell that locally there is neither isotropy nor homogenity (you can see quite far up into the sky, but not so far into the ground). Moreover, there are differences in isotropic pressure, convection, heat conduction, and shear stresses between the air and ground, none of which are features of the perfect fluids in the FLRW model. So locally the FLRW metric is not suitable, and since the Earth is very much not vacuum de Sitter is even less suitable. Consequently it should not offend anyone to read that Manhattan isn't undergoing cosmological expansion. Most things within ten kiloparsecs of here are gravitationally collapsing. It requires coordinate contortions to interpret interplanetary or interstellar space in the Milky way as expanding, and switching to different systems of coordinates will blow up that interpretation.
A "swiss cheese" universe with collapsing vacuoles in an expanding cosmology reflects that it's only when we go from ~kpc length scales to ~Gpc length scales that the distribution of matter behaves enough like perfect fluids to allow for an exact solution to the Friedmann equations. The collapsing vacuoles are usually modelled like Lemaître-Tolman-Bondi with a thin shell boundary; this results in a vacuole that time-orientable and has fewer spacetime points in the future direction. "Hole" time functions and "cheese" time functions must be different (hole clocks tick slower as they fall towards the centre).
For those who aren’t in the know physics is in a crisis where huge portions of theoretical physics are turning out to be complete nonsense.
https://news.ycombinator.com/newsguidelines.html