Anonymous at Fri, 7 Jun 2024 17:06:40 UTC No. 16220102

Fluid-like spacetime confirmed

Anonymous at Fri, 7 Jun 2024 17:13:01 UTC No. 16220124

>>16220095
This isn't new - the understanding that spacetime curvature requires a distribution of mass-energy, not strictly mass, has been understood since its inception. Curvature due to radiation is already included in the Friedmann equations. I also remember a slew of papers from a few decades ago looking at the possibility of using high intensity lasers to induce spacetime curvature. There was one crazy motherfucker even looking at exploring it as a means of creating wormholes or time travel.

It doesn't eliminate the need for dark matter though, since the effects of curvature due to radiation are already factored in.

Anonymous at Fri, 7 Jun 2024 18:27:10 UTC No. 16220256

>>16220095
>Gravity Can Exist Without Mass
Well, I haven't read the article yet, so I might be saying something wrong or redundant, but if you define "gravity" as space-time distortion, independently of the presence of mass or not, we've known that electromagnetic radiation negatively curves space-time for a good while. so that's a form of negative gravity.
Thanks for the link

Anonymous at Fri, 7 Jun 2024 18:28:11 UTC No. 16220259

>>16220256
>>16220124
anon beat me to it, nice.

Anonymous at Fri, 7 Jun 2024 18:30:43 UTC No. 16220273

>>16220124
Anon, me again, I posited a hypothesis to my girlfriend a few months ago (she's a physics fanatic, lol): in the great voids of space, where the most abundant for of energy is EM radiation, would that not deform spacetime negatively? And would that effect not be responsible for "dark energy"?
Dark energy just might be the expansion of spacetime in that way. If there is no matter, spacetime is expanding.

Anonymous at Fri, 7 Jun 2024 18:47:46 UTC No. 16220305

>dark defects

Anonymous at Fri, 7 Jun 2024 18:50:04 UTC No. 16220315

>>16220095
and this explains why some galaxies have lots of dark matter and others have almost none how?

Anonymous at Fri, 7 Jun 2024 19:04:07 UTC No. 16220334

Any dark matter in our solar system? Wouldn't the math prove it?

Anonymous at Fri, 7 Jun 2024 19:23:02 UTC No. 16220362

>>16220334
>Any dark matter in our solar system?
Yes, the galaxy is at the center of a diffuse cloud of dark matter.
>Wouldn't the math prove it?
I have no idea what you're trying to say here.

Anonymous at Fri, 7 Jun 2024 20:14:14 UTC No. 16220467

>>16220362
How come Newton didn't need Dark Matter?

Anonymous at Fri, 7 Jun 2024 20:33:49 UTC No. 16220513

>>16220467
>How come Newton didn't need Dark Matter?
because they didn't have instrumentation to study the heavens like we do. Back then, they could see smudges in the night sky, "nebulaue", but they didn't know what they were or how far it was. It was only in the early 20th century that Edward Hubble showed that those objects were much further away that anything we had ever imagined.

Anonymous at Fri, 7 Jun 2024 21:25:21 UTC No. 16220638

>>16220362
>diffuse
Really?? If there is FAR more dark matter than normal matter, why on earth should it be diffuse in our galaxy?

Anonymous at Fri, 7 Jun 2024 21:33:03 UTC No. 16220656

>>16220638
Because the dark matter halo is mind-bogglingly enormous. You really just have no idea how big it is. It's incredibly massive and incredibly diffuse.

Anonymous at Fri, 7 Jun 2024 21:41:39 UTC No. 16220677

>>16220638
Without pressure and friction dark matter particles cannot collide and lose momentum to collapse into the center of the gravity well. The normal matter can, it cools and becomes denser in the middle until stars form. If dark matter only significant interacts through gravity then it's very difficult for it to collapse on small scales, it takes a long long time.
A similar effect can be seen with elliptical galaxies. They are thought to be produced by mergers, where you end up destroying the galaxy disks can getting a big smooth blob. Because the stars are collisionless the stars can be orbiting in random and opposing directions, unlike a spiral galaxy there doesn't have to be one direction of rotation. The stars don't slow down and just form a spheroidal blob (a lot like a dark matter halo).

Anonymous at Fri, 7 Jun 2024 22:18:09 UTC No. 16220741

>>16220256
>we've known that electromagnetic radiation negatively curves space-time
This is new to me. Does that mean building an alcubierre drive isn't scifi.

Anonymous at Fri, 7 Jun 2024 22:42:06 UTC No. 16220782

>>16220102
I know you don't want to say eather but you mean it.

Anonymous at Fri, 7 Jun 2024 22:48:18 UTC No. 16220801

>>16220782
Aether in the old theory was a solid. It had no fluid properties, no "flow". Moreover it supported transverse waves, its very reason for being, something only solids can do.

Anonymous at Fri, 7 Jun 2024 22:58:08 UTC No. 16220823

>>16220801
>transverse waves
Like gravitational waves?

Anonymous at Sat, 8 Jun 2024 01:22:33 UTC No. 16221036

>>16220467
The same reason Newton's didn't need special or general relativity or quantum mechanics - his understanding of the universe was limited to local mechanical motions over a very limited timescale (planets, projectiles, colliding objects, simple machines, etc.)

Anonymous at Sat, 8 Jun 2024 02:52:46 UTC No. 16221146

>>16221036
Newton was limited?

Anonymous at Sat, 8 Jun 2024 04:42:11 UTC No. 16221285

-1 + 1 = 2.8. ?

Anonymous at Sat, 8 Jun 2024 14:50:46 UTC No. 16221951

>>16220801
Like literally now I'm interested about wave propagation in supercritical CO2.

Anonymous at Sat, 8 Jun 2024 15:05:09 UTC No. 16221972

>>16221146
Well yeah, obviously. He lived in a world of falling apples and cannonballs. We live in a world of electrons and black holes. We need better theories than Newton's.

Anonymous at Sat, 8 Jun 2024 15:41:10 UTC No. 16222084

>>16221972
He invented calculus, which we still use today. We invited the big bang and string theory, which are already in question.

Anonymous at Sat, 8 Jun 2024 16:52:48 UTC No. 16222291

>>16222084
You think noone questioned newton in his time?

Anonymous at Sat, 8 Jun 2024 17:07:46 UTC No. 16222313

>>16220095
Dark Matter fags on suicide watch.

Anonymous at Sat, 8 Jun 2024 17:22:38 UTC No. 16222332

>>16220124
It's still weird to me that photons, following null geodesics, can warp spacetime due to their energy. I can only imagine it as leaving some kind of conic distortion behind it but I don't think that's what the field equations imply. The photons should be able to warp space ahead of it, modifying its own null geodesic. Fucking weird shit.

Anonymous at Sat, 8 Jun 2024 17:24:40 UTC No. 16222334

>>16221146
Underrated joke that the midwits here didn't get. I got your joke though anon. It is appreciated

Anonymous at Sat, 8 Jun 2024 18:03:45 UTC No. 16222411

>>16222313
>Oh, our model doesn't need dark matter
>All it needs is invisible spherical shell singularities made of negative matter and matter. No idea why galaxies form like this.
And it can't even explain the asymetric lensing in that cluster in your image.

Anonymous at Sun, 9 Jun 2024 00:36:17 UTC No. 16223295

>>16222334
Dunka,

Anonymous at Sun, 9 Jun 2024 00:43:19 UTC No. 16223306

>>16220124
>There was one crazy motherfucker even looking at exploring it as a means of creating wormholes or time travel.
are you talking apout fat mexican looking guy with dead father?
i remember seeing him in some shitty popsci documentary as a kid

Anonymous at Sun, 9 Jun 2024 00:44:49 UTC No. 16223310

>>16220273
nah energy including em radiation still produces positive curvature

Anonymous at Sun, 9 Jun 2024 13:07:15 UTC No. 16224327

>>16220677
If there was zero interaction with normal matter, why would dark matter gather around galaxies?
Either it would gather around galaxies, in which case it would gather around earth,
or it would not gather around galaxies, in which case I would not expect much dark matter on earth.

Anonymous at Sun, 9 Jun 2024 18:17:58 UTC No. 16225042

>>16223306
Cannot believe his father's actually dead.

Anonymous at Sun, 9 Jun 2024 20:04:36 UTC No. 16225231

>>16224327
>If there was zero interaction with normal matter, why would dark matter gather around galaxies?
It still interacts through gravity.
>Either it would gather around galaxies, in which case it would gather around earth,
Nope, it is very hard to capture an object only with gravity.
Say you have a particle which only feel gravity and stars from a large distance with no inital velocity. It falls towards the Earth, potential energy changes into kinetic energy. It passes through the Earth without EM interactions. The particle loses energy slowly as it climbs out of the Earth's gravitational potential well. And returns to the radius it started at but on the other side. It would then oscillate.
But now imagine that particle has a little bit of positive velocity to start with, the particle can easily escape the gravitational potential of the Earth. DM particles in the Milky Way halo would all have their orbital velocity, easily enough to escape the Earth. You can only capture gravitationally if there is a three body interaction.
Also in the case of galaxies it's different because the dark matter halo forms with the galaxy. That can bind particles because the gravitational potential grows.

Anonymous at Mon, 10 Jun 2024 00:29:47 UTC No. 16225868

>>16220741
It also means that UFOs are real.