Can Space Time Remember?

[@maxmustermann5590]

Man when I started watching I was still in college, now im 30 and Matts beard is going grey. Hope the show keeps going strong for at least another decade

[@paulmichaelfreedman8334]

10 years next year (that Matt presents it)

[@tjentalman]

That's not enough

[@ianmccombs5624]

In some frames of reference, he already has!

[@DANGJOS]

@@paulmichaelfreedman8334 10 years already?! no freaking way!!

[@oatlord]

I've watched since the guy before Matt. I'm more a fan than you. My fan cred is immense.

[@mitchellwilley7208]

I just wanna thank PBS Space Time for all the hard work and great videos they create. I didnt know any physics and now i have a deep understanding of how the universe works. You guys inspired me to learn physics. Thank you.

[@pbsspacetime]

Please remember to shout us out when you accept a nobel prize for your theory of everything!

[@patentpendulum]

You don't know physics. These are all public release contents, specialized in making the public amazed. Don't be a fool. To know physics, you have to actually read.

[@KashishKebab]

​@patentpendulum what indicates that this channel is the only research they've done? It could have been their jumping off point. More importantly, why are you such a rude thief of joy?

[@patentpendulum]

@@KashishKebab that's the point, don't make something a jumping off point by watching some KZbin videos.

[@stankythecat6735]

I LOVE this stuff. It stretches my brain… it’s so amazing

[@jtgullickson6117]

To Matt and the team at PBS Space-time, thank you for your years of dedication and service providing us (the general public) such an in depth and resourceful insight into quantum physics, astrophysics, and all that is space and time. I've been watching since the days of calculating what planet Mario is on to jump as high as he does. Since the previous host... You enrich my life and satisfy my intense curiosity of the universe we live in. I live for this. Thanks again, JT Gullickson. From Canada. Love and Peace

[@faenethlorhalien]

Yes, but can it remember the 21st night of September? Love was changin' the minds of pretenders while chasin' the clouds away...

[@tyresefarrell]

Best comment😂

[@pbsspacetime]

Earth, Wind & Fire Remembers

[@frtzkng]

Listen for the bongo man

[@thomaslawrence2210]

😅​@@frtzkng

[@chrisladd5855]

It's crazy that you're having this right now. I'm about to submit a paper. Thank you for everything. I will be sure to note all the helpful comments and wonderful teachings on BAO.

[@Itachi21x]

I hope Matt never stops hosting

[@StarkRG]

I've been looking forward to LISA since LIGO started detecting things. The precision of detecting the position of the spacecraft relative to the other two is astounding and got me thinking about something I first wondered about in my early teens, extremely-long baseline _optical_ telescopy. It's a relatively simple matter to take data from two radio telescopes on opposite sides of the Earth, do some calculations and, boom, you get the resolution of a radio telescope the size of the Earth (though with only the light-collecting ability of the area of the telescopes). You _should_ be able to do something similar with visible light, but because they're so much smaller than radio waves, you can't just collect the data and do calculations afterwards, the light has to be collected at a single location and it has to take the same amount of time to arrive. I think it's been done at smaller scales of single telescope installations, but even that's pretty difficult. I'm guessing atmospheric disturbances would make it pretty much impossible at more extreme distances. But what if there wasn't an atmosphere? You could do it on the Moon, though you'd be dealing with moon dust, and line of sight isn't all that big on the Moon anyway which would mean you'd need to add extra complexity in the form of mirrors to redirect the light over the horizon (and each one would have to be just as precisely configured as the telescopes themselves. Orbital telescopes would be best, but you'd have to be _extremely_ precise with positioning each member of the fleet relative to the detector so that the light-speed delay from each collector to the detector is exactly the same. But LISA shows that kind of precise positioning is actually possible. So imagine a small constellation of Hubbles in a polar orbit with only mirrors collecting and focusing light on a detector craft that would be orbiting perpendicular to the constellation (or maybe stuck in a Lagrange point). Orbiting them around Earth would probably be the easiest, but if we got them to orbit the sun instead, we might be able to get some _really_ high resolution imagery. I don't think we'd be able to resolve an Earth-sized planet any bigger than a single pixel, but maybe we'd get a few pixels of a Jupiter or Saturn-sized planet.

[@jasonharrison25]

Ever since the imaging of the two black holes a few years ago. I always wondered why they couldn't do the same thing with the size of Earth's orbit around the Sun. That would be substantially higher resolution then just the size of the Earth

[@DeathlyTired]

Made me sit up! I thought Matt said, "Thank you Raytheon for supporting PBS". That's an interesting development I thought. Ah! Raycon! (mental note to get ears checked)

[@Wanhope2]

Listen if Raytheon will keep PBS fighting against misinformation and conspiracies then let’s goooo

[@arcade_signal]

Raytheon did sponsor PBS Nova

[@Kohl293]

We will shoot missiles at a neutron star

[@ProbablyNotAChicken]

Fancy space rocket is just one component away from being fancy space missile!

[@nefdsnet]

So Dr. Serova was right and regular deformation due to FTL propulsion causes cumulative damage. Better limit cruising speeds to warp 5 until we can come up with variable geometry warp fields that will be able to prevent further damage.

[@Turnoutburndown]

"The universe is very old, but it remembers." Why was this so ominous!? 🤣

[@kennethaunstrup]

Dark Matter is really the Universes Big Book of Grudges and it is just waiting for the perfect opportunity to get even.

[@sozetsukokai9327]

Okay, spill it. What did you do to the universe? 🤨

[@kellymoses8566]

And it holds grudge!

[@patemblen3644]

Perfectly normal paranoia.

[@bananabourbonaenima]

3:00 This is not strictly true: water waves create Stokes' drift, which is a net displacement of water in the direction of the wave.

[@MrAntipaganda]

Whoa. Just at the surface, yeah?

[@doublepinger]

It's also not true for electricity. Electron drift velocity is a thing.

[@MarkusAldawn]

​@@doublepinger It's also not true for Mexican waves. At higher energy levels, fans have known to end up several seats away.

[@bananabourbonaenima]

@@MrAntipaganda It tails off with depth en.wikipedia.org/wiki/Stokes_drift

[@justbsufti]

Greetings from downunder. I love your videos, thank you. I have only 1 complaint, the only continent not shown in the intro is our home land. 😅 Keep up the great work.

[@ChinnuWoW]

How does it feel living in upside-down land? You ever get worried that you’ll fall into the sky?

[@ilkoderez601]

It's fun to think about the elasticity of space time! Good episode!

[@Alex-js5lg]

One idea I've heard for the explanation of dark matter is that black holes might leave a small, permanent kink in spacetime after they evaporate. Neat idea.

[@bangyahead1]

There is no evidence that a black hole has ever evaporated. The universe isnt old enough for that.

[@Stagliaf]

I just posted a similar comment. It’s an interesting idea to think about

[@Ravus_Sapiens]

Without seeing any math on it that seems unlikely; there would have to have been a *lot* of black holes. For their remains to account for 27% of the mass of the universe...

[@ChinnuWoW]

But doesn’t it take googols of years for Hawking Radiation to evaporate a black hole entirely?

[@PhilipMurphy8]

Always a great moment on Thursday when PBS Space Time uploads a video

[@cianoconnor6081]

“The universe is old, but it remembers” will sell a few hoodies for sure

[@MikeNelson1953]

Expected a mention of the pulsar array gravitational observatory, but I guess it detects much longer waves than the memory effects.

[@klauskervin2586]

Thank you Matt and PBS Space Time crew for another great video!

[@Thats_A_Dummy_Name]

Thanks for this video. One major question arises here: What happens to conservation laws? Like energy and angular momentum. It seems this effect can increase or decrease these values arbitrality.

[@safestate8750]

This is super interesting, I have never heard of gravitational memory before.

[@zazoreal5536]

Ah a Triangle so close to my heart!

[@peteshively5552]

Thank you for doing this topic. I read an article about gravity with no mass and i didn't really understand. When i finished it i thought....i hope SpaceTime does a video on this.

[@edibleapeman]

"Gravitational Spin Memory" sounds like the name of a late-90s techno/hiphop band.

[@Novastar.SaberCombat]

You spin me right around. 💫🪐💫

[@DFloyd84]

Or some sci-fi technobabble to describe a super-advanced alien civilization's information storage system. "You encode information one megabyte at a time on magnetic media? The Pak-Thak Interstellar Imperium perfected gravitational spin memory to store trillions of petabytes over one hundred thousand of your years ago."

[@elliotsmith9812]

I would love to hear an engineering analysis of LISA. Especially the relationship between orbit, mass vs. sensitivity and resolution. What limits the orbits to where they are going to be? Can it be upgraded by adding more satellites? What exactly gets upgraded? What happens when the satellites get more massive?

[@fionacankat]

Last time I was this early the electroweak force hadn't split yet

[@objective_psychology]

another PBSST banger

[@MCsCreations]

Fascinating. I imagine the effects it could have on time!

[@timmykline4691]

6:15 this animation always looks to me like a Neptune-sized triangular spaceship chasing earth

[@LordZordid]

It's always good to give engineers something to do. Otherwise they get into trouble.

[@ntnwwnet]

I'm not sure if _space time_ can remember, but I know 100% for sure that Pepperidge Farm remembers.

[@thepetrologist]

Greetings m’lord. What is the process of chosing a topic? What if you have a schedule and there is a new exciting research paper? Are some some topics in reserve?

[@mentatphilosopher]

I always thought that the assumption that spacetime is Euclidean at some distance from mass is ripe for questioning. Even a small curvature caused by mass passing by, over a large enough volume, would look like additional mass.

[@drdca8263]

Isn’t it thought that average curvature is negative, as in de Sitter space?

[@lool8420]

Absolutely love Space Time, always comes with super creative graphics, vids that helps people like me see what's being discussed in my mind's eye. Keep up the amazing work Matt and the team

[@jyrinx]

Guys. You _have_ to talk with whoever is titling the videos. Every time the video is about spacetime, the thumbnail says “spacetime” but the title says “Space Time” (when referring to the science thing, not the show).

[@bigsarge2085]

Fascinating.

[@dekumarademosater2762]

Love your work, want to see more -SO GET WELL SOON!

[@petegaslondon]

Like .. What?? I'm just a humble electronics tech I'm used to spacetime being.. The usual springy stuff - most your concepts i can just about wrap my head around but .. Seriuosly? An INEVITABLE conclusion of GR? (As yet never independently verified?) The analoge of the waves i get, like 'drift velocity' (movement of actual electrons) to signal velocity (which can be a ways faster, up to c) but still, ulinearities in spaceime itself? That REALLY does my head in - "I want to believe"

[@richteffekt]

Good job figuring out the scienc-y part of my upcoming time travel novel. Man, you're always that one step ahead of me 😅

[@futuristica1710]

Well, I don’t know about that but I will always remember what time and space did to me!

[@WalterGordyCanada]

Pepperidge Farm remembers

[@Deletirium]

I used to be irritated by meme comments, but then I spent the night at a Holiday Inn.

[@michaeldaignault-h4p]

Lol

[@adreanmarantz2103]

....and there it is!

[@l.mcmanus3983]

Could gravitational memory effects be partly responsible for the Hubble tension?

[@KarelPletsStriker]

Hi, gravitational wave physicist here. Small correction on how LISA's interferometry works. It doesn't actually work like a physical interferometer because the lasers would become too faint at such long distances to do it the normal way. Instead, it basically times the distance a photon takes to go from one detector to the other in 1 direction, and then the interferometric pattern you would normally get is reconstructed through a technique called Time Delay Interferometry (TDI)! Sadly the data analysis for LISA is quite different from the previous ground-based detectors and everyone's slightly panicking about it

[@ilkoderez601]

I need to know the dimensions of the mat. I could be playing Magic The Gathering on a PBS Spacetime mat! ...Matt, thank you for the great episodes.

[@pbsspacetime]

Let us know if 90cm x 45cm (35.43in x 17.71in) is good for a Magic the Gathering Mat!

[@ilkoderez601]

@@pbsspacetime Yeah, that's good. A standard playmat is 24x14in

[@danieldevito414]

This is the basis for Alastair Reynolds' FTL comms called Galactic Final Memory in his book Chasm City, part of his Revelation Space series. Couldn't recommend those books enough

[@kellymoses8566]

That series starts so well but ends so bad.

[@veervishalmishra4526]

I am watching your video from 8th class , thanks to give trustful information

[@popeconstantine8839]

I just love watching 5 ads in 16 minutes, great show

[@DobrinWorld]

Very informative, thank you for all good job all you guys do! 🎉

[@mNag]

If gravity propagates at causality as does light, then wouldn't there be a way to explain a kind of tired light?

[@charlesjones9860]

Only 4ish minutes into the video, but my new hypothesis: could the constant addition of memory by the equally constant events producing waves, be stretching the fabric of space-time itself, and therefore be at least partially responsible for the expanding nature of the universe? Fascinating stuff.

[@davidmedlin8562]

My thoughts as well.

[@t.c.bramblett617]

Memory adding information and therefore causing expansion :o

[@elementsofphysicalreality]

Hey PBS Space Time, I’ve had this idea for a while now. A theoretical field. Quantum fluctuations take time to annihilate. When created near the event horizon of a black hole, the pair falls toward it. It has a speed. This means there is a distance at which, if far enough, they have enough time to cancel before interacting with the event horizon. But within that distance, the pairs get a chance of being split. If one of the virtual particles touches the event horizon, the other is granted positive energy via quantum tunneling. This makes the one that touches negative and takes mass/energy from the black hole. The other one has to get emitted and that’s hawking radiation. It gets propelled outward in a line from the singularity the negative particle at the event horizon and itself. The amount of energy this takes is taken from the black hole as the negative particle. How does the black hole lose mass/energy? The negative particle cancels out with an equivalent amount of information from the black hole being projected onto the event horizon as 2D info. This cancels out and teleports the info via quantum entanglement to the escaping particle thus not losing info in the process of Hawking radiation. There would be 2 zones. The initial zone of all pairs that qualify for this interaction within a defined distance based on the Schwarzschild radius. And then a 2nd zone which would be very very small. The distance of how far the virtual particles were apart from one another at the moment the one touches the event horizon and the tunneling starts.

[@elementsofphysicalreality]

Therefor if you traced a particle of Hawking radiation back to the source it would get EXTREMELY close to the event horizon and then disappear. You wouldn’t see it go backward for that half second 10^-24 seconds to be precise traveling a distance of 10^-16 meters. You wouldn’t observe that because it happened backwards in time. Which is possible due to the Heisenberg uncertainty principle. What am I missing? I’ve watched all of your videos. All of them. Even the one that says not to think of these things as particles because they’re really waves and you had the awesome visuals on it. Even so, they’re still particles. And particles need logic classical thinking. No?

[@kenmercer8112]

Your not wearing a print shirt today, but when you do, those are never in the store. :( great show!

[@objective_psychology]

This is really exciting! This would rule out a lot of dark matter and dark energy theories!

[@traywor]

This is super exciting, maybe we'll make some progress gravity. How should I visualize those imprints on space? If exaggerated, does that mean that parts of space have different scalings which would rip bodys apart if they flew into those? It is hard to imagine space being stretched, because stretching in my mind happens inside space not to space. Could at some point in the future, space gets so messed up, that there could be wholes or barriers ins space time? How would they look like? I have so many questions...

[@antirealist]

Ahhhh always love to hear Soft Gold by Frederic Mauric Fortuny

[@donhodgkinson6233]

Yes another great video

[@sc0or]

“Near zero” is limited with a size of region where you are able to subtract atom’s energy. It’s about a vacuum chamber in a laboratory. More likely a point where s laser is focused. And I cannot imagine a natural process which can still pick an energy of an atom while it’s “freezing” and growing in size up to size of a galaxy

[@petergreen5337]

❤Thank you very much for this helpful lesson Matt

[@neilgreening9609]

Not sure i agree with the elastic band analogy at the start i.e. it just returning to how it was. All sorts of changes will have happened to the material as part of the stretching - similar “small levels” of affect as quoted for some of the gravitational wave caused changes…. ?

[@KazmirRunik]

There certainly seems to be a lot of mass being dragged either way by the Bullet Cluster interaction... Seems like a neat little thought experiment 🙃

[@ejakez]

I can't find that Standard Model night light anywhere on your merch store. Just hoodies/Ts & the totally rad coffee mug. But I need that night light, don't be shy

[@slenderman3310]

You know, with the advent of dark energy and gravitational waves, it really seems to me that space actually expands a lot, it just that the speed of the expansion is always equal to the objects velocity and so we pretty much never notice until it gets extreme. it really feels like space expansion is just two gravitational field pulling on each other until they snap and create more space time, after all you can have a dip without a rise since it reality there both the same thing. My theory is this is how orbits actually work, space expands and contracts evenly creating a perfect rotation.

[@grayjphys]

Was just watching a TOE episode about how quantum mechanics can be written as a classical nonmarkovian stochastic process. Pretty neat that there are actual memory effects in gr

[@axle.student]

That was an excellent interview. My head is still attempting to unravel some parts of it lol > Back to this gravitational memory idea. The implications of that are also quite profound. The concept of space time not being elastic and not returning to a previous equilibrium after gravity effect has passed is difficult to imagine. For example as an extreme thought experiment, if a Black hole evaporated does the space-time around where it was remain stretched/warped?

[@KageSama19]

Wait, if wave bunching can happen in spacetime, shouldn't frame dragging cause a buildup of spacetime at the event horizon of a blackhole?

[@robsin2810]

I love your effort to try to explain Gods creations.🙏🇦🇺👍

[@JerehmiaBoaz]

Yeah, my car remembers its physical interactions with other traffic too. The fact that even empty space can be dented is depressing in so many ways.

[@pandoraeeris7860]

The universe is a state based machine. The arrow of time couldn't exist without 'memory'.

[@PerpetuallyTiredMusician]

Beneath the smoothed out pillow case of nothingness of yesterday's gravity well there is the memory foam of space time.

[@ZackaryOkerson]

open inquiry Say, hypothetically, assuming you were invulnerable and immortal and you were able to hover just above the BH event horizon and you threw your strongest, possibly cyborg, punch at the void. What would happen? Would your arm get spegetified off, come back out, as if punching a ghost, or just be stuck on the other side (preventing you from moving ever again unless you remove the arm)? Would it try to finish pulling you in or would escape be impossible regardless of hypothetical, possibly cyborg, propulsion methods? Would different size BHs have different outcomes? inquiry submitted

[@drdca8263]

Things on the outside of the event horizon and staying at a fixed distance from it, certainly wouldn’t remain connected to things on the inside. I think if slowly lowering any material made of atoms towards the horizon would probably result in it either getting torn apart before reaching the horizon, or pulling in whatever it is dangling the thing in, depending on how hard the thing lowering the thing can hover. (Tensile strength of the material vs how much acceleration you can manage)

[@GoldenAgeMath]

On November 29th I might have to buy one of everything

[@theaxer3751]

To me it sounds like the memory is in the objects occupying spacetime, not in spacetime itself. Just like ramping up your sound system to max volume. After turning it back down it still plays the exact same music, but you'll hear it differently because of hearing damage.

[@ChalkyWhiteChalkyWhite]

if i can remember, then surely the universe can remember!!

[@Anthony-ru7sk]

I hope space time can remember me forever

[@andywood6376]

This question is deeply important for the people playing deep into the significant digits of Einstein’s equations.

[@jonasga]

You made us Matt O'Proud

[@CashFlowTV554]

"I want to believe" lmao

[@ethanrichardson6362]

When measured, the curvature component of the Freidmann equation is equal to zero so it shouldn’t effect GR though it’s fairly disputed whether it should be equal to zero and therefore if the measurements are accurate.

[@Broomlad]

Wow. Reminds me of the Shattering described in Legend of the Obverse.

[@donald-parker]

My understanding is that the LISA satellites have micro thrusters that allow corrections during their mission to maintain precise distances from each other. How would we distinguish between a correction and "gravity wave memory"?

[@lilied1]

How is this video a coincidence? I am writing my thesis about longitudinal waves, oscillation and surface ripples and all the bs that comes with waves and currently it's in the middle of the night and i wanna fall asleep to a space time video and the topic is again oscillatory movements and waves. Am i cursed or is the universe mocking me🤦🏻‍♀️? This feels personal!

[@grayshadowglade]

I am certain it is either mocking you or there is some computational limit to the randomness of the system such that things tend to emerge in parallel due to low quality random number generation. :-)

[@PedroHenriquePS00000]

the more i watch this channel the crazier concepts i learn... like MEMORY??? like what??? i wonder if time is relative, and if time passes differently at different locations, i wonder if the diferences between two timezones of the universe causes an effect. and if that is exploded to infinity (the differences) isnt that a event horizon? aka what im saying is, maybe blackwholes arent dark because gravity sucks it in, but instead because time moves so fast, that light that is moving at a lower speed than the speed of light, is actually being accelerated through time itself to a speed in our perspective that seems faster than light. (but at the particle perspective its just as fast as it always was...) so its dark because that patch of the universe is in the future, it simply doesnt exist yet... and maybe galaxies are infinetely larger than they appear, but they are condensed inside the blackwhole. (i say that because i say that because what holds a galaxy in place is the time differences between the inner stars and the outer stars, so it holds it like a glue., but maybe that isnt just limited to the visible part of the galaxy at all...

[@efdbjon2114]

the whole idea of space-time and general relativity is that there is no difference between slowing/speeding time and somethings velocity. I think it makes sense to think of it as time moving slower and the particle is moving at a different speed. However, it makes no difference how you chose to view it.

[@michaelblacktree]

Scrolling for Pepperidge Farm comments; was not disappointed. 😎

[@bloodyorphan]

We currently think the "memory" is caused by Super Symmetry. It is the reason particles persist, leading to any element in the periodic table. i.e. Temperature causes a form of Velocity persistence Governed by the Lorentz Gamma equation v/c=ºC

[@MeissnerEffect]

I’m so glad I fell in love with science before the world went insane. I have all I need in the reassurance of empirical research and observations. 🦋✨

[@fuseteam]

It would be interesting if you could cover lisi's E8 Supposedly 4D spacetime arrises from 8D chargespace

[@Yury_Panbolsky]

Another way to understand gravity is "Conceptual Content of the Generalized Theory of Gravitation of Jefimenko" and O. Efimenko "Gravitatation and Cogravitation".

[@petrisz]

fascinating

[@MegamanXGold]

Assuming you could scale up a pair of atoms in a solid at near zero such that each atom is the size of a galaxy, without fundamentally breaking those atoms, are there any properties of those atoms that can be compared to galaxies? Would the distance between the two atoms be greater than the distance of the Milky Way to Andromeda? Would the atoms be more or less likely to collide versus the inevitable mixing of Milky Way and Andromeda? Of course I'd also be curious about how spacetime would affect atoms forced to that size, but this isn't a question about how atoms themselves would behave at those sizes.

[@dnswhh7382]

How can length changes be detectable by Lisa, when those spacecrafts have to be arranged in space at first? I mean, they get there by rockets and then manoevered perfectly into their position. How can this happen so accurately, that we at the end measure light wave contractions, which are not related to tiny, tiny steering rocket adjustments?

[@drdca8263]

Is this really a memory effect in the spacetime? This sounds like it just has the effect of moving objects around a bit, and the memory is in the distance between the objects? I guess maybe it doesn’t involve acceleration of those bodies through spacetime, and so it is the amount of space between them changing, but like… It doesn’t seem like the spacetime afterwards is like, actually different in ways that could be detected if there weren’t objects there at the time that the wave passed by?

[@viinikellari]

If we could have greater accuracy with measurements (more watts/higher frequencies needed probably) we could use singularities as a gravitational lens to probe even "deeper". Due to the inaccuracies and limitations in the present day mathematics, things like "beginning of the universe", infinite curvature/density or "no spacetime beyond singularity" are most likely glitches and misinterpretations caused by the inaccuracy. Imagine trying to record 20kHz signal with a microphone having a 100Hz max sample rate. Yeah. You'll get artifacts and glitches. So no Lawrence Krauss, virtual particles do not "come out from nothing" and neither does the universe "come from nothing" : ) Just because our maths and methods are not absolute and perfect, doesn't mean we should reflect our limitations to what we assume or interpret about reality.

[@wedothework4105]

Does space time have a density? I'm watching a PBS Spacetime on gravitational memory effects. They're going on to explain how passing gravitational waves can sometimes leave a permanent deformation of spacetime. With gravitational waves being an oscillating compressing and stretching of spacetime, my layman brain hears that spacetime can become more or less dense depending on the phase of the wave. Then, with the idea that an event can leave a permanent stretch in some area of spacetime, what would that look like passing from "normal" spacetime through an area of stretched or less dense spacetime?

[@Hiddensecret9]

Space-time doesn’t "remember" in the conventional sense, but the universe is governed by the second law of thermodynamics, which states that entropy (disorder) tends to increase over time. In this sense, the arrow of time could be seen as a kind of "memory" of past states-where things evolve toward greater disorder.

[@michaelccopelandsr7120]

Time is fascinating. I worked the subway stations for nearly 10 years. From one end of the city to the other. Every so often I would notice the city would be saying that, "Today just flew by" or "The day was just dragging along." How can an entire city, with no interaction with each other until they used the subway, complain about the same time paradox? Unless they were all effected by the same outside, "interference." MAYBE a time distorted bubble the earth passes through in its revolution around the sun. MAYBE they're the effects of gravitational waves. Either side of the wave effecting time just enough for we humans to notice. Making time seem to drag on the upside and fly by on the downslope. Or, vice versa. MAYBE they're given off by the sun. MAYBE they're from outside our Solar system and reach us in intervals. ???? 🎶Ti-i-i-ime, is on my side. Yes, it is!🎶 If you can think of a better way to do a blind survey of an entire city, in the small window of opportunity, I'm all in. Until then, I invite you to spend a couple years in the subways during rush hour and you'll see for yourself. Just listen as an entire city gets off of work and gets out of school. You'll see it's more than a, "coincidence of circumstances."

[@yellstr]

Not directly related but… if space-time is elastic, then the frame-dragging process should slow down the rotation of black holes (or, maybe, any rotating body), right?

[@seanlynch8339]

could permanent 'ripples' in spacetime be seen on the cosmic scale? For example could it be seen in the distribution of cosmic filaments, or in the distribution of the CMB across space?

[@banditbloodwyndevs8782]

Hm, I think I didn't get it completely. When a gravitational wave hits LISA and the side lengths are changed after it, couldn't that be just caused by the wave moving the probes a bit relative to each other? That wouldn't be a permanent effect on spacetime itself, just a little push on objects within spacetime.

[@tykinn]

Imagine a membrane-- but it's not like the one you're thinking of. It's enveloping everything-- and everything inside of any instance of a thing. And inside of its components, and their components, and so on. It can fold in on itself, around itself and anything else. That sounds a bit mad, but that's basically radio. Spacetime itself logically necessitates a memory in order for it(*or anything, actually) to persist. Figuring out how to forensics the universe is an entirely different problem though 😅

[@mattsharsing]

A black hole is by definition a memory of spacetime since the matter that created it is no longer there. There is nothing there, no matter, only the singularity. Thus - a memory.

[@Jokers_Yugioh666]

What's the end game to all of this??

[@markdeloria20]

Rubber bands can have "memory", but it takes awhile. Just keep over-stretching it and it loses elasticity. Or it could snap.