lisper 8 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 7 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.

    [1] https://en.wikipedia.org/wiki/Zeno%27s_paradoxes#Dichotomy_p...

    • A_D_E_P_T 7 hours ago

      There's a much simpler escape: That space is ultimately discrete (i.e. that there's an elementary length) rather than infinitely continuous.

      • analog31 3 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 3 hours ago

          I'd subscribe to your religion but for the division.

          • nomel 2 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 2 hours ago

              That sounds a bit shifty.

      • JumpCrisscross 7 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.

      • astrange 4 hours ago

        If space is discretized, we should see "upscaling artifacts" in the CMB, but we don't.

        • defrost 3 hours ago

          Maybe we would .. but Musk has to turn off his leaky Starlink over the Murchison (not so) Quiet (anymore) Zone first.

          • astrange an hour ago

            We got space telescopes and stuff.

            • defrost 20 minutes 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.
              
              ~ https://en.wikipedia.org/wiki/Cosmic_microwave_background

              Hmmm, it appears the ground based results were a dramatic improvement over the sat based data.

  • _cs2017_ 2 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.

  • enkid 7 hours ago

    Just because you can't record something doesn't mean it doesn't exist.

    • asdasdsddd an hour ago

      Sure but i can invent infinitely many unfalsifiable claims that mean nothing

    • lisper 7 hours ago

      Who said anything about recording? What would the subjective experience of measuring something with infinite precision possibly be like?

      • JumpCrisscross 7 hours ago

        > would require somehow recording an infinite amount of information...

        >> Just because you can't record something...

        >>> Who said anything about recording?

        • lisper 6 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 5 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 2 hours ago

              You'd need to somehow record refinements endlessly? I don't get what you're getting at.

            • lisper 4 hours ago

              How do you measure pi?

              • JumpCrisscross 3 hours ago

                > How do you measure pi?

                Pick your method. It’s the ratio of a circle’s circumference to its diameter.

                • winwang 44 minutes 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.

  • A_D_E_P_T 7 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.

    • JumpCrisscross 7 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.)

  • woopsn 4 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.

    • lisper 4 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 3 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
  • oniony 8 hours ago

    It would simply be written down on an infinitely long strip of paper.

    • __MatrixMan__ 7 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 3 hours ago

        The shelving down there is frictionless, so they're often not so nearby.

    • tonetegeatinst 7 hours ago

      Möbius strip for double surface area....I can practically see the cheese TV comercial

  • pazimzadeh 7 hours ago

    I have similar reasons for not believing that the world that we experience is a computer simulation.

  • ur-whale 6 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.

gcanyon 3 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.

kelseyfrog 8 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 8 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 7 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 7 hours ago

        Black holes also have a charge!

    • JumpCrisscross 7 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 8 hours ago

      Since when is the surface of the universe that of a hypersphere?

  • thebricklayr 7 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 6 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!

      • tsunamifury 3 hours ago

        You know string theory is now generally considered a large scale fraud perpetrated by cox to maintain funding right?

        • defrost 3 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.

          https://en.wikipedia.org/wiki/String_theory

        • WantonQuantum 2 hours ago

          Found Sabine Hossenfelder's HN account!

          I am, of course, joking but she posts this sort of easy and empty clickbait.

          • tsunamifury 2 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.

  • lisper 8 hours ago

    Because if you free-fall into a black hole you can go past the event horizon.

    • kelseyfrog 7 hours ago

      Can we? Is there a way to test this assumption? If not, then it's not science, right?

      • mr_toad 4 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.

        • kelseyfrog 4 hours ago

          I think the test involves communicating your results. It's the same thing with the afterlife

          • amoss an hour ago

            Publish or perish made manifest.

    • JumpCrisscross 6 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.

  • bongodongobob 7 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 3 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.

    • JumpCrisscross 6 hours ago

      > surface implies an interior, otherwise it's a just a point

      Space-time is not Euclidean geometry under GR.

      • mr_toad 4 hours ago

        But it is continuous, at least until you hit or pass through the singularity.

        • JumpCrisscross 3 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 7 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 7 hours ago

        ? It by definition has a radius of 1.

        • krukah 7 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 an hour ago

            Minor nitpick, the ball might be closed or open, depending on whether the boundary is included or not, respectively.

JohnMakin 8 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 7 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 2 hours ago

      Same here. I gave up on reading it once the diagram animations made it near impossible

  • WantonQuantum 5 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 3 hours ago

      As a less sophisticated audienc emember, can someone PDF the thing for me my vision wetware can't grok it

  • wholinator2 7 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".

  • selimthegrim 8 hours ago

    How could it be made more accessible to you?

    • oniony 7 hours ago

      They could be regular web pages without the silly scroll animations, just like in the good old days.

    • rmbyrro 6 hours ago

      Just make it a web page, not a powerpoint presentation.

    • JohnMakin 8 hours ago

      reader mode supported. sometimes they are sometimes no.

  • mopenstein 7 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 6 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.

    • the_gipsy 7 hours ago

      You're a moron if you believe these two things compare even remotely

johnsanders 7 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?

  • ruthmarx 2 minutes ago

    That you can split any finite length into an infinite amount does not equate to having to traverse infinite numbers.

  • wzyoi 6 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.

DiscourseFan 7 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 7 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 3 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.

    • 23B1 3 hours ago

      I too am wanting to know the answer to this question, sounds like an intriguing concept!

ur-whale 6 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.

nyc111 5 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.

tsunamifury 3 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.

gcanyon 3 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.

AIorNot 6 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.