[HN Gopher] Where do space, time and gravity come from?
___________________________________________________________________
Where do space, time and gravity come from?
Author : digital55
Score : 97 points
Date : 2022-05-06 08:10 UTC (14 hours ago)
(HTM) web link (www.quantamagazine.org)
(TXT) w3m dump (www.quantamagazine.org)
| seydor wrote:
| Well from the structure of our brain of course
| joncp wrote:
| Sean Carroll is a master of making quantum mechanics approachable
| to non-physicists. Here are a few of his talks:
|
| - Fermilab 2013: https://youtu.be/gEKSpZPByD0
|
| - The Royal Institution 2014: https://youtu.be/_8bhtEgB8Mo
|
| - The Royal Institution 2020: https://youtu.be/5hVmeOCJjOU
| TheMightyLlama wrote:
| I love that there are people far more educated than me who are
| also paid to explore these topics.
|
| A while ago I was pretty certain that gravity was emergent and
| was caused by Gluon Colour Confinement. Here was my incredibly
| naive rationale:
|
| Assumption for the purposes of this idea that gravity is not an
| absolute, gravity is an emergent phenomenon.
|
| My logic
|
| Gravity around a black hole Photons can't escape Heavier
| particles and even molecules can't escape
|
| Gravity around a planet sized mass Photons can escape Heavier
| particles and even molecules can escape
|
| Gravity is not a force that acts at a distance (absolute)
| Spacetime is being dragged into any object with mass (emergent)
|
| ---
|
| We are not being 'pulled' into the earth We are being 'kept
| under' by a shower of space time being consumed
|
| ---
|
| What causes this 'consumption' of spacetime around objects with
| mass?
|
| Gluon color confinement
|
| https://gist.github.com/TheMightyLlama/135fd67eb0577c34093ca...
| galcerte wrote:
| >I love that there are people far more educated than me who are
| also paid to explore these topics.
|
| Sadly, there's some of us who would explore these topics, yet
| the pay and some of the conditions surrounding this profession
| are less than ideal, so to speak.
|
| Also, you might want to study the math around the strong
| interaction and gravity before making any speculation like
| that. What is explained to you in words might not be accurate.
| audunw wrote:
| That's interesting. I've had the opposite thought: that
| spacetime is created by particle interactions, and so mass is
| essentially "shedding" spacetime. You'd think this would push
| other particles away, but the process of spacetime being shed
| away from a mass would be slow, but the increased density
| caused by spacetime creation would cause particles to be
| attracted in the direction of higher density.
|
| In black holes, this process would break down in a particular
| way such that it's not possible to create more spacetime.
| That's why the amount of information a black hole can store
| grows with the area of the black hole, not the volume. There is
| no spacetime inside it for information to enter.
|
| I feel like this could explain "dark energy".. spacetime piles
| up in the empty regions between galaxies, and the curvature
| isn't strong enough to create significant attraction, so at
| that scale, things end up moving away from each other. So
| basically the same idea you had I think, but opposite.
|
| I believe in a stochastic process for wavefunction collapse,
| and I think entanglement may be related to the process of
| spacetime creation. Entangled particles are connected by a
| single filament of spacetime. This filament can only be used
| once before being destroyed, so it'd participate in the
| "resolution" necessary for wavefunction collapse, but then
| disappear. That is: there is no "spooky action at a distance"
| because from the entangled particles perspective they're still
| right next to each other in the graph of spacetime.
|
| It was interesting to see that Stephen Wolfram seems to be
| suggesting something along those lines, but I'm not smart
| enough to understand if my ideas are similar to what he's
| proposing. I'm probably completely wrong anyway.
| monkeycantype wrote:
| >"spacetime is created by particle interactions", I wonder if
| space is particle interactions. In the basic physics classes
| as part of a biology degree, I've used a lot of formulas
| where the strength of an interaction between objects
| increases with proximity. What if its the other way around?,
| the strength of interactions between particles is proximity
| and the sum of interactions between all particles we
| conceptualise as space.
| andrewgleave wrote:
| I like how this is currently the top-voted comment.
|
| It a great example of the fundamental process at the root of
| all humans progress/knowledge: a creative conjecture/idea which
| can (hopefully) be tested against reality and rejected or
| accepted based on how well it solves the problem and explains
| something about reality.
| blarg1 wrote:
| Maybe matter is like a balloon and gravity is like air pressure
| pushing on it.
| lesgobrandon wrote:
| qwerty456127 wrote:
| Why isn't it enough to consider spacetime (not space and time
| separately) the only thing existing, and its everything else
| being its properties (e.g. gravity - curvature)?
| mr_mitm wrote:
| Because then you apparently end up with two incompatible
| theories: quantum mechanics and general relativity.
|
| Treating space and time as emergent may be a potential
| solution.
| TheOtherHobbes wrote:
| I'm probably missing something, but "First assume there's an
| abstract wavefunction and see what happens if everything is
| entangled" seems to me like a classic example of begging the
| question.
|
| It's traditional to derive equations and functions from higher
| principles, not to work back from them.
|
| You _can 't_ assume there's a wavefunction, because it's a
| metaphysical position. You're literally assuming an entire
| mathematical apparatus just sort of exists for no reason, in some
| wholly unspecified way, in an unspecified medium, with completely
| unknown properties.
| whatshisface wrote:
| You can establish the wave function and entanglement by doing
| experiments unrelated to gravity, so if gravity comes out of
| them that's still fairly impressive. (I am not sure if it
| actually does.) You are right that making assumptions and
| reasoning from them does not itself make your conclusions true,
| but it does change the "input port" where you have to plug in
| your empirical observations to some proposition hopefully more
| easily demonstrated.
| titzer wrote:
| If the universe can be described by finite information, it kind
| of doesn't matter if the theories are unified into one equation.
| Even if the description of the universe is just a list of Planck-
| length time frames of states--a very long, very large _execution
| trace_ , if you will--it being finite information would mean that
| its description, when encoded into bits, using whatever encoding
| you like, would necessarily appear in the bits of pi[1],
| somewhere. Which means a complete snapshot of our universe, in
| fact every possible finite-information universe, exists stored in
| pi. In that eventuality, it's already over, bro!
|
| [1] Or any transcendental number, for that matter, or any truly
| random sequence.
| paskozdilar wrote:
| Note that pi is not known to have this property, but it is
| expected to be true.
|
| Also note that it is not true that any transcendental number
| must have every finite sequence of digits in its decimal
| expansion. A common counter-example would be a Liouville
| number: sum k=1->inf (1/10^k!) = 0.1100010000
| 000000000000010000000000000000000000000000000000000000000000000
| 0000000000000000000000000000000000000000000001...
|
| Which is proven to be transcendental [0], but still does not
| contain a digit "2" in its decimal expansion, so therefore it
| does not contain all finite sequences of numbers.
|
| You were probably thinking of Normal numbers [1], pi is widely
| believed to be a normal number.
|
| [0] https://en.wikipedia.org/wiki/Liouville_number
|
| [1] https://en.wikipedia.org/wiki/Normal_number
| titzer wrote:
| Interesting, thanks.
| mescaline wrote:
| Spin. Everything that has gravity eventually spins, so spin
| produces gravity and gravity produces spin. Even the moon spins,
| so I must be right.
|
| Also, if you spin someone in a barrel, it produces a force that
| is indistinguishable from gravity, for the person in the barrel.
| Simple, but scientists like to make things complicated and
| confusing. Probably makes them sleep better at night.
|
| See Newtons bucket argument. Spin is relational to the universe.
| If something spins, it produces gravity gradients. These come
| from differing frames of reference to time, or more specifically,
| variance in the pace of causality.
| bell-cot wrote:
| Alas, no. Inside the barrel (or any other spinning frame of
| reference) you get various pseudo-forces -
| https://en.wikipedia.org/wiki/Coriolis_force - with objects
| traveling in curved paths, and other weirdness. :)
| panda-giddiness wrote:
| I mean, this is just factually incorrect - a pion is a spin-0
| massive particle, e.g. (for that matter, a photon is a spin-1
| massless particle).
| marginalia_nu wrote:
| If spin causes gravity, why doesn't a ferromagnet get lighter
| above the curie temperature?
| tempodox wrote:
| I have a theory that to answer the question "where does X come
| from?" you need a viewpoint outside of X. Since we're presumably
| incapable of attaining a viewpoint outside of space, or time, I
| wouldn't expect any answers beyond more or less educated guesses.
| chrisjc wrote:
| Not that I proclaim to have any idea how to answer any of these
| questions, but there is something about the question of time
| that I can never get past. And I feel like it's similar to what
| you're saying?
|
| What happened before the big-bang? If time is a product of the
| big-bang, then how can it be used to provide any sort of
| perspective outside of the very thing that created it? (poor
| phrasing, sorry)
|
| Imagine asking the question "what was @tempodox2 like before he
| was born?".
|
| Moreover, our ability to perceive time shapes our way of
| thinking about it, potentially in ways that lead us to
| incorrect theories and conclusions. Simplest, although maybe
| worst example might be that time is actually flowing in the
| opposite direction that we perceive it. Isn't the direction of
| time just a subjective observation based on who or what the
| observer is? We have just happened to evolve with certain
| sensors that allow us to perceive time in a particular
| direction as a result of a subset of properties/reactions
| potentially exclusive to our universe.
| dotnet00 wrote:
| I think asking "what happened before the big bang?" is to an
| extent the same as "where do space, time and gravity come
| from?", but not in the sense that they're trying to obtain an
| external (to the universe) perspective.
|
| The latter isn't trying to obtain an external perspective,
| but rather a more fundamental perspective, somewhat like how
| when you dig deep enough, the weak and electromagnetic force
| become unified, emerging from more fundamental properties.
| Similarly, with space-time and gravity being so heavily
| associated, there may be a more fundamental mechanism at work
| which is responsible for the properties of both.
|
| The former is asking something potentially similar. In the
| early universe, there's a popular theory that the weak,
| strong and electromagnetic force were unified. Similarly, if
| the mechanisms for the properties of space, time and gravity
| can be unified, perhaps we may find that the big bang itself
| wasn't as much of a singularity as we think, instead being
| the result of some more fundamental properties of the
| universe being in a certain state. Thinking of it like the
| idea of a false vacuum decay, perhaps the fundamental
| properties of the universe were the same before the big bang,
| and the 'bang' was the vacuum dropping down to a more stable
| state, in which case "what happened before the big bang"
| makes some sense.
|
| On the other hand, if the big bang was indeed the start of
| all physics including time, the big bang very well can have
| happened because this question would be asked.
|
| As for our ability to perceive time shaping our way of
| thinking about it, from what I understand, we currently
| believe that physics holds under simultaneous charge, parity
| and time reversal. The various promising theories of quantum
| gravity have cases that might break this rule, which I think
| would effectively define a physical direction of time.
| andrewxhonson wrote:
| I like this quote about this from Stephen Hawking: [1]
|
| > "One can regard imaginary and real time as beginning at the
| South Pole, which is a smooth point of space-time where the
| normal laws of physics hold. There is nothing south of the
| South Pole, so there was nothing around before the Big Bang,"
| Hawking said.
|
| My layman's reading of that imagines if you move south, get
| to the south pole, and then keep going the same direction you
| had been going, you are still moving but no longer going
| "south." In this metaphor, you could go back in time, be "at"
| the Big Bang, keep going the direction you had been going in
| time, but the direction you're going would no longer be
| "before."
|
| I have no idea how practical this metaphor is and how far it
| extends, but it's an appealing one to me. Maybe someone else
| could clarify.
|
| [1] https://www.cnet.com/science/stephen-hawking-tells-
| degrasse-...
| fosk wrote:
| Fun speculation.
|
| What if our reality (and universe) is on the same journey
| as the one you just described? What if the North Pole is
| our starting point (Big Bang), we walk southward and as
| soon as we cross the South Pole, everything reverts back
| into the Big Ben (you would eventually reach the North Pole
| again) just to start all over again. Like a piston, or a
| ballon that is being inflated, then deflated and re-
| inflated again; our reality is just "one stroke" (or
| "walk", in your metaphor) of a bigger "engine".
|
| Somebody else commented about this:
| https://physicsworld.com/a/new-evidence-for-cyclic-
| universe-...
| Eddy_Viscosity2 wrote:
| Indeed, it could be we are just not capable of understanding
| it for what it really is and the best we can do is make
| models that we can understand that fit some parts of what we
| see, but not all. We try new models but with the same
| results. We'll never be able to get it all right because its
| beyond of capacity.
|
| Or
|
| It's just something that we haven't figured out yet, and
| eventually will.
| atonalfreerider wrote:
| Roger Penrose came up with a very plausible theory that the
| heat death of our universe looks like the big bang moment,
| from the perspective of a photon. So our universe is caught
| in a cycle of birth death rebirth ad infinitum.
|
| [0] https://www.indiatoday.in/science/story/big-bang-didn-t-
| star...
| paulrouget wrote:
| iirc the CMB clues he's talking about to justify the CCC
| have been ruled out.
| philipov wrote:
| While Penrose's specific theory is probably not correct,
| it does provide a conceptual framework to imagine how
| such clues might be possible.
| hathym wrote:
| but what created that loop in the first place?
| scollet wrote:
| It's possible that there never was a first place.
| nonameiguess wrote:
| This reminds me of some physicist I can't remember trying to
| refute William Lane Craig's formulation of the Kalam
| Cosmological Argument, a classical Islamic argument for the
| existence of God going something like:
|
| 1. Everything that begins to exist has a cause.
|
| 2. The universe began to exist.
|
| 3. Therefore, the universe must have a cause of its
| existence, and that cause is God.
|
| The issue is with the first premise. If you only understand
| causality from within a temporal framework, then your
| understanding only works from within a temporal framework.
| "Everything that begins to exist has a cause" presupposes the
| cause exists before the effect and that presupposition
| becomes incoherent at the beginning of time itself. If the
| big bang is the start of time, then nothing exists "before"
| the big bang because the very notion of "before" is
| meaningless without time. Our understanding of every event on
| the universal timeline is that it is linked inextricably by
| necessity and sufficiency to some set of prior events, and we
| call that causation, but attempting to use the same logic and
| language regarding the existence of the timeline results in
| paradoxical, meaningless statements.
| swat535 wrote:
| The Cosmological argument was posited by Plato (c. 427-347
| BC) and Aristotle (c. 384-322 BC). It has nothing to do
| with "Islam"..
|
| It is comical to claim that some "physicist" has managed to
| resolve a deeply _philosophical_ question such as Creatio
| ex nihilo.
|
| The existence of God is a philosophical question and not a
| scientific one. One can't reach for a scientific method to
| resolve everything; if that were the case, then we might as
| well throw out the entire domain of philosophy all
| together.
|
| I fully recognize that this is not a very popular comment
| on a forum like HN, however what I dislike about
| "Scientisim" today, is that they claim that the entire
| realm of human knowledge and experience can be reduce to
| Science alone.
|
| I hold that this line of thinking forces you into a very
| narrow and reductive line of reasoning.
| cecilpl2 wrote:
| > What happened before the big-bang?
|
| Perhaps this is like asking the question "What value did the
| system clock have before the computer was turned on?"
| AnimalMuppet wrote:
| Well, before the big bang, there had to be some environment
| that was such that a big bang could occur. (Just as, before
| the computer was turned on, there had to be a computer
| there to turn on.)
|
| The question may be unanswerable from the information
| available in this universe (or, in the analogy, within the
| computer), but we know that there had to be _something_
| there.
| rgrieselhuber wrote:
| Similar to Godel's incompleteness theorems.
| simonh wrote:
| Exactly, you can't verify a system using that system, so
| maybe it's not possible to exactly specify all of mathematics
| and physics within our universe.
|
| Roger Penrose applies this thinking to the problem of
| consciousness and thinks this points to a special
| characteristic of humans that we can decide if things are
| true by 'stepping outside' of a problem, and that no
| mathematical function can do this. Therefore no computer
| running a mathematical function can be like us in that way.
|
| Well no, not if it's a consistent system, but why does it
| have to be consistent? We're not consistent systems and we
| build systems that aren't consistent all the time, including
| computer systems.
| rgrieselhuber wrote:
| Exactly. This is one reason I inherently distrust all
| closed-loop systems.
| jasomill wrote:
| _People say again and again that philosophy doesn't really
| progress, that we are still occupied with the same
| philosophical problems as were the Greeks. But the people who
| say this don't understand why this has to be so. It is because
| our language has remained the same and keeps seducing us into
| asking questions. As long as there continues to be a verb 'to
| be' that looks as if it functions in the same way as 'to eat'
| and 'to drink', as long as we still have the adjectives
| 'identical', 'false', 'possible', as long as we continue to
| talk of a river of time, of an expanse of space, etc. etc.,
| people will still keep stumbling over the same puzzling
| difficulties and find themselves staring at something which no
| explanation seems capable of clearing up.
|
| And what's more, this satisfies a longing for the transcendent,
| because in so far as people think they can see the "limits of
| human understanding," they believe of course that they can see
| beyond these._
|
| -- Ludwig Wittgenstein [1]
|
| [1]
| https://archive.org/details/culturevalue0000witt/page/n44/mo...
| meroes wrote:
| This is scary when applied to consciousness to. How will we
| ever understand what makes consciousness from within
| consciousness?
| amelius wrote:
| Someone else's consciousness?
| morelisp wrote:
| Formally, this philosophical position is called mysterianism.
|
| https://en.wikipedia.org/wiki/New_mysterianism
|
| This can be either because one posits a fundamental
| limitation on self-conceptualization of systems, or a
| practical one on human biological or social intelligence.
| Byamarro wrote:
| We did discover though that the Earth is not the center of the
| universe without leaving it. Then with Newton we could learn
| where the arrangement of planets come from. Then Einstein
| developed further the knowledge about gravity without leaving
| the gravitational field.
| RcouF1uZ4gsC wrote:
| But we could observe things outside of earth.
|
| We cannot observe anything outside of space and time.
| Byamarro wrote:
| We still did conclude how gravity more or less works while
| being within gravitational field.
| snarfy wrote:
| It's debatable [1]
|
| [1] - https://physicsworld.com/a/new-evidence-for-cyclic-
| universe-...
| TecoAndJix wrote:
| I hope this is true. Then I get to be immortal by nature
| of the infinite monkey theorem. I'll always come back!
| https://en.wikipedia.org/wiki/Infinite_monkey_theorem
| nonameiguess wrote:
| This is actually terrifying in many respects. It's the
| basis of the eternal return idea, probably best known
| from Nietzsche, but found in many traditions. It
| compounds the consequences of anything that ever happens.
| Without it, you can at least take comfort in knowing
| anyone with the misfortune to live and die under chattel
| slavery, Naziism, or some other great evil at least only
| had to do it for one lifetime and then they get to escape
| forever to eternal peace. In a cyclic infinite monkey
| universe, nope, everything that ever happens happens
| infinitely many times, and those people who spent their
| entire lives on a plantation in fact spend eternity on a
| plantation. It's hell but real, and not levied as
| punishment but by pure randomness.
| simonh wrote:
| Except they're not the same person, they're just (mostly)
| variations on people that happen to be similar. It's a
| big universe. If it proves to be even more staggeringly
| big, well, it's more than I can comprehend either way.
| albrewer wrote:
| Ugh, I can't believe you'd repost something you've
| already said 70 trillion years ago
| jameshart wrote:
| Question seems malformed. The answer to a 'where' question is
| referenced to 'space'. 'Where does space come from?' is as odd a
| thing to ask as 'when does time come from?', 'how do methods
| work?' or 'why are there reasons?'
| [deleted]
| marginalia_nu wrote:
| Maybe it's my philosophy-addled brain, but I think these all
| sound like excellent questions.
| bqmjjx0kac wrote:
| The answer to "where do babies come from?" is not "a uterus".
| jameshart wrote:
| That seems like an excellent, factually accurate answer to
| me.
| AnimalMuppet wrote:
| It answers the immediate cause, but there's a _lot_ more
| than that going on. Because the answer ignores all the rest
| of what 's going on, it's a bad (but still accurate)
| answer.
| lesgobrandon wrote:
| madaxe_again wrote:
| This was a great read, and it was heartening to be reminded that
| there are plenty of talented physicists out there who aren't
| afraid to lift the rug and see what's under there.
|
| I noticed, as I progressed through my studies of physics, a
| tendency for people to go from "what if" to "it is" before
| finally reaching "what if" again, as their knowledge grew and
| developed - I think many went into it for the same reason as me,
| seeking explanations for reality, and there's a tendency to
| mistake theory for explanation, if it's explanation you're
| looking for.
|
| All of it, from QFT to Cartesian coordinates to mathematics
| itself is just a construct that we humans have come up with to
| create a rational framework of information that can describe
| reality - but as anyone who has ever written software knows,
| there are many ways to reach the same behaviour with different
| underlying code.
|
| It's all essentially reverse engineering from a point where you
| begin without even language or the concept of logic, and
| everything, everything that you have to work with is the stuff
| you've created, outside of the black box of the universe - but
| made only with the stuff of the black box.
|
| I moved diagonally into computer science and philosophy, as I was
| only ending up with more questions the deeper I went into physics
| - and the whole information as reality concept has stuck with me,
| as it's the only part of all of our frameworks which remains a
| consistent truth.
|
| I think our next big breakthrough in understanding will likely
| come not purely from physics, but the intersection of physics and
| computing, as I think we will come to realise that they are
| essentially one and the same.
| Comevius wrote:
| Information thermodynamics is a fertile research field that
| gave us a lot of insight into physics, and also chemistry and
| biology. Beyond solving Maxwell's daemon (one of the early
| clues that information is physical and intricately linked to
| thermodynamics) experimentally, we can also build tiny machines
| fueled by information, so called information engines.
|
| I'm not sure how this relates to quantum gravity, I think that
| one is going to be harder to figure out.
| mhh__ wrote:
| Unless it's one more systemd feature, it's Maxwell's "demon"
| Koshkin wrote:
| It's kind of amazing to me that in a 100 years a whole lot of
| extremely smart, and very focused, people couldn't arrive to a
| verifiable way of bringing together QM and GR. There's something
| wrong with this situation.
| dschuetz wrote:
| I think, that's because they are too focused trying to bring
| together 2 things that don't fit. Apparently they aren't smart
| enough to take a couple of steps back, and start over. That is
| not something that is encouraged in the scientific community.
| Failure is rarely getting any attention, and even frowned upon,
| only success is relevant. Yeah, I agree, that's just amazing
| and terribly wrong.
|
| EDIT: I mean, who does revisit long established facts everybody
| just agrees upon, without checking, because they are long
| established?
| simonh wrote:
| In fundamental physics, that's literally what it's all about.
| We know some of our assumptions must be wrong, because we
| know the theories we have conflict. That's been perfectly
| clear since the time of Einstein and Bohr. One thing that has
| been hugely helpful has been data such as from the big
| particle colliders, but that data is getting harder and
| harder to get as the required energies have gone through the
| roof.
|
| The thing is there is no shortage of theories, or whole
| classes of theories, the problem is getting the data we need
| to verify and refine them.
| Ar-Curunir wrote:
| Lol the arrogance in this comment. "The hundreds/thousands of
| people who work on theoretical physics are just too dumb to
| step back and take a look at the big picture."
| notshift wrote:
| I don't think it's arrogance, I think you have far too much
| faith in large groups of people.
|
| Of the 4.4 million software developers in the US, most of
| them produce really bad code and have a lot of wrong ideas
| about development and don't think twice about what they're
| doing.
|
| Same with the medical field - rife with dysfunction and
| malpractice.
|
| Pretty much all fields work like this as far as I can tell.
| It sometimes takes hundreds of years for new correct ideas
| to be actually accepted and integrated into the mainstream
| knowledge/practice in any given field. Most people have
| giant egos and are resistant to change.
| [deleted]
| prof-dr-ir wrote:
| Perhaps we are just not smart enough? After all, you cannot
| teach a dog quantum mechanics...
| IAmGraydon wrote:
| I've held this belief for a long time. We tend to think we
| have the brainpower but we just need the understanding. I
| think it's far more likely that we have nowhere near the
| brainpower required to understand the true nature of reality.
| scollet wrote:
| You are the system understanding itself. Your brain is
| distributed.
| the_only_law wrote:
| I've ironically thought the seams about fully understanding
| the human brain.
| contravariant wrote:
| Perhaps, but I'm partial to the interpretation that we simply
| don't understand quantum mechanics well enough to explain it
| to, if not a dog, children in high school.
|
| Note that we do teach classical mechanics (to a point) in
| high school, even though it was the cutting edge of physics
| at some point.
| mr_mitm wrote:
| There is an argument to be made that there could be a phase
| transition when it comes to the ability of understanding
| things.
|
| When you manage to write down your thoughts so future
| generations can build on prior work, and when you manage to
| formalize problems by abstract notation (math), and when you
| gain the capability of breaking down complex problems into
| small solvable chunks, then maybe, and I want to stress
| _maybe_ , there is no limit to understanding things.
|
| On the other hand, there also may be problems with
| irreducible complexity, so it really could be either way.
| chasd00 wrote:
| i've thought about this too. When the only tool you have is a
| human brain you try to solve everything with a human brain.
| im3w1l wrote:
| What I wish someone would do is a double slit experiment, where
| the path of the photon is long enough to be affected by
| gravity. Maybe then there would be some clues to quantum
| gravity in the interference pattern.
| ledgerdev wrote:
| It was 250 years between Newton's and Einstein's discoveries,
| so give it another couple hundred years or so. These things
| take time to bake LOL.
| dcolkitt wrote:
| In particular the bottleneck is often the math, rather than
| the inability to understand physical reality. Earlier
| thinkers grasped at what Newton said, but couldn't get very
| far without the scaffolding of calculus. General relativity
| required complex non-Euclidean geometry and would have been
| simply impossible even a few decades prior.
| slowmovintarget wrote:
| In this case, the bottleneck has been a deliberate refusal
| to work on the underpinnings of QM. The Copenhagen
| "Interpretation" refuses to consider what a measurement is,
| and creates an artificial separation between a quantum
| system and the system taking the measurement. For sixty
| years, adherents were told to "shut up and calculate"
| rather than ask questions like: Isn't the apparatus taking
| the measurement also a quantum system? Why should there be
| two sets of rules, one when a measurement is made and one
| when a measurement does not occur? What is it about
| measurements that cause this? What mechanism is going on in
| the universe that causes it to appear to function in the
| classical, emergent way, the world of Newton and
| Relativity, rather than in superpositions and spooky action
| at a distance?
|
| Part of the reason little progress has been made is that it
| was considered career-ending in physics to work on those
| questions, because some of them dive into philosophy (What
| is knowledge? What is real? What is emergent?) Throughout
| the latter half of the twentieth century graduate students
| were counseled away from any work related to the field.
| Oppenheimer famously organized the shunning of Bohm for
| daring to publish (at Einstein's encouragement) on the
| subject. Hugh Everett was driven out of academia
| altogether.
|
| Hard problems can be solved when people actually work on
| them. Often the problem is other people preventing the
| work. Thankfully this attitude seems to be easing thanks in
| part to the efforts of people like Sean Carroll and Lee
| Smolin.
| Koshkin wrote:
| But an interpretation is just that - an interpretation,
| which does not have any effect on the equations (or does
| it?), so if it's a new math that is needed for QM and GR
| to start looking like two ends of the same elephant, then
| that's what it'll take.
| slowmovintarget wrote:
| Bohm and Everett proposed theories that are
| mathematically distinct. Today there are families of
| theories (Objective Collapse, Hidden Variables, and
| Everettian Mechanics) that are mutually exclusive.
|
| One of Sean's papers, in fact, proposes a way to falsify
| Everettian mechanics through experiment (though the
| experiment would be exceedingly difficult in practice).
|
| Copenhagen was "just an interpretation" but serious work
| on the subject is actually advancing work on new theories
| (with distinct mathematical models), not just hand-waving
| and dismissal.
| spaetzleesser wrote:
| Relativity also needed data that we only could produce and
| end of the 1800s and beginning of the 1900s
| yuvalr1 wrote:
| It is really amazing, and they even discuss it in the podcast.
| What the interviewee basically says is that quantum mechanics
| is the reality of how things work, and that classical physics,
| including general relativity, is an approximation of how QM
| works in large scales. In the end he says one day we may be
| able to think of an experiment to measure the things the
| theories don't agree upon. He guesses this may come from
| experiments around Lorentz invariance.
| spaetzleesser wrote:
| Maybe it's just really hard and needs data we have trouble
| producing with current technology?
|
| It took hundreds of years between Newton and Einstein and
| relativity was only possible once we were able to produce data
| about the speed of light.
| wheelerof4te wrote:
| "There's something wrong with this situation."
|
| Or, there is something wrong with the theory?
| Koshkin wrote:
| There is nothing wrong with a theory being wrong. (They are
| all mostly "linear approximations" anyway.)
| Cthulhu_ wrote:
| I mean it's possible, but there's not been any successful
| alternatives - and I'm confident we've had smarter people
| than Einstein and co work on it.
| tablespoon wrote:
| > It's kind of amazing to me that in a 100 years a whole lot of
| extremely smart, and very focused, people couldn't arrive to a
| verifiable way of bringing together QM and GR. There's
| something wrong with this situation.
|
| What's wrong about it? If humans evolved, there's no good
| reason to think that even the smartest human has the mental
| capacity to do something like that, or to do it quickly.
| Science will hit a wall determined by human limits, and it's
| quite possible that limit has already been hit in some areas.
|
| There are a lot of popular fairy tales that portray humans as
| universal understanders (with no limits as long as they
| Science(tm) hard enough), but they seem kind silly to me.
| simonh wrote:
| Maybe it's a hard problem, harder than a few techies on HN are
| willing to give credit for. I mean if you think it can't be
| that big of a deal, maybe you could give us a solution to the
| problem of motion in gague theories of matter, to help us out?
|
| https://arxiv.org/abs/2008.08967
| taylodl wrote:
| Part of the reason is for the past 100 years we've been teasing
| out all the details of these theories and verifying them. We've
| only recently discovered where the incompatibility of these
| theories present problems - and now we're tackling them. What
| I'm really saying is there hasn't been a _whole lot_ of people
| trying to bring together QM and GR, not to the level that 's
| going on at present. For those who had been trying to reconcile
| the two theories they were working with theories in progress,
| theories who's impacts were just being understood. As another
| commenter mentioned these things take time to bake!
| criddell wrote:
| Do you know if Tegmark's mathematical universe hypothesis bring
| them together?
| meroes wrote:
| He does call for a radical reformulation of which math to
| study, as he wants to avoid some issues of arithmetic,
| infinity, and incompleteness.
|
| Maybe his discrete, computable mathematics (which is merely
| alluded to) is the temporary step back we need to move
| forward again.
|
| Although removing the continuum from QM seems questionable.
| AFAIK (which isn't much) continuous change is a feature of
| QM. It's one reason quantum computation has an advantage. No
| 0 or 1, but a continuous range of states somehow.
| evanb wrote:
| Not in any specific way that cures any issue.
| tootie wrote:
| It took like 200,000 years to get to F=ma, then 200 to get to
| relativity. I think we're moving at a breakneck pace. It's just
| a really tough nut to crack.
| titzer wrote:
| It took almost 400 years to prove Fermat's Last Theorem. But it
| _was_ proved. Some things just take a big pyramid of knowledge
| to reach.
| swayvil wrote:
| Maybe there is no underlying pattern to be discovered. Maybe
| reality is fundamentally chaotic and any form is just a local
| effect.
|
| Heck, that form might not even be consistent between "bubbles".
| jonnat wrote:
| An episode from Sean's podcast in which he builds the argument in
| more detail:
| https://www.preposterousuniverse.com/podcast/2019/09/09/63-s...
| derbOac wrote:
| Seems to me that you'd have to have a better understanding of
| quantum mechanics before it's applied to gravity, given that
| gravity is usually thought of on scales much larger than QM. I'm
| having trouble explaining what I mean by that, but an entity like
| a star isn't a particle, it's a system of many particles, which
| is where people have trouble with QM -- cf quantum computers.
| Seems like we'd have to have a better understanding of system -
| level quantum dynamics before really understanding gravity (or
| maybe understanding gravity would give leverage to something like
| quantum computing?)
| [deleted]
| meroes wrote:
| Interestingly QM is also the theory of the very large.
| Entanglement is not attenuated by distance while gravity is.
| Also in aDS spacetime (closed rather than open topology, not
| our known universe) new observables would come into play which
| reflect off the edge of the universe. Also two black holes can
| be entangled.
| derbOac wrote:
| Yeah good point. By "scale" I meant more like "numbers of
| elements" or something, size in that sense more than physical
| size, although I guess I was kind of thinking of them as
| similar. But you're right that space size and numbers of
| things size aren't necessarily the same.
| awinter-py wrote:
| feels like 20th century physics was us learning everything about
| every particle you're likely to encounter in your day, and what
| they do when they touch
|
| but all we really know about _space_ is that it makes quantum
| systems touch once in a while
|
| (and that galaxies don't rotate at the right speed)
|
| feels like we're waiting for a 'weird but up close' result in
| space so we can start doing experimental physics on it. _maybe_
| this is nonlocality / entanglement tricks, but my money is on
| benchtop black holes
|
| I quite like this 1876 pop sci article about 'are the elements
| elementary' -- shows what a top 1800s chemist thought about the
| coming subatomic revolution. I wonder what the 2022 equivalent of
| this essay is
|
| https://books.google.com/books?id=CSIDAAAAMBAJ&pg=PA463
| steve76 wrote:
| arminiusreturns wrote:
| My personal, completely layman's theory, is that the dual
| universe theory is the localized correct approach (there may be
| other dual universes outside ours), and that at the big bang
| matter on the other side became entangled as it entered our
| universe (or dimension?), and that in some sort of cosmological
| osmosis, matter that broke that barrier and became entangled
| seeks to return to it's original state (in the other universe) or
| some similar sort of equilibrium, likely through black holes and
| white holes. (eg, other universe a white hole here would look
| like black hole there, and vice versa). Gravity pulls stuff
| together until it finally collapses into creating a semi-
| localized blackhole (explaining the theory of a blackhole in
| every galaxy). Gravity in this case would then be a second tier
| effect of entanglement which is locally weak but cosmologically
| strong, with gravity being the opposite. If this were the case,
| the main place to focus for experimental predictions to reveal
| more on this would then be probably be anti/dark matter
| experiments.
___________________________________________________________________
(page generated 2022-05-06 23:01 UTC)