Live data from Hacker News

Einstein's Other Theory of Everything

nautil.us

51–60 of 138 posts

Re: Einstein's Other Theory of Everything

#51

Earlier quoted context omitted.

And your comment is a perfect demonstration of the fragility of the universe: what if the OP edits and corrects their typo? Edit: edited after 57 minutes - pedantic nerd here :)

not possible after 5 minutes

We are talking relativity here, beware with time lapses and Lorentz transformations!

Re: Einstein's Other Theory of Everything

#52

Earlier quoted context omitted.

Balls on sheet is a wrong model imo. It needs gravity to work and therefore doesn't explain gravity. I like to imagine a sponge. If you could somehow make dense lumps inside the sponge (may be apply heat in its center somewhere using microwaves?) everything around that lump will be feel a tension/attraction towards that lump. That's my mental model.

I think the balls on sheet is an OK compromise. The reason for me is, it's tough (but not impossible as you point out) to visualize functions over 3D space. Your sponge does that and I like it! (You could also use color-coding, vector-gradients etc) The ball and sheet uses a spacial dimension as the function value, and that's the dimension the needs gravity to work acts on. So, if you accept that as a compromise, it'…

I like to explain it all as graph paper where the squares get bigger or smaller depending on what’s near them.

Re: Einstein's Other Theory of Everything

#53
post #3

An alternative to the “ball on rubber sheet” model of gravity is “twisting a lump out of a sheet of silly putty.” You get the same curvature without relying on gravity to serve as a model of gravity (which always bothered me a bit) For clarity, here’s what I mean: if you flatten out some silly putty (or pizza dough should work) then pinch and twist together some of the sheet into a lump, that pulls along the surround…

The recursive model always bothered me too. That’s nice, though harder to explain in words.

You can compromise: take a rubber net. Now bunch up a number of squares together and hold them with your hand. What happens to the bigger squares? Now explain that mass likes to move from smaller squares to larger squares and towards the bunched up areas.

Re: Einstein's Other Theory of Everything

#54

Earlier quoted context omitted.

I don’t believe you can entangle items remotely like that.

photons entangle at a distance as there is tech in the market right now in cryptography that uses entangled photons over distances of several miles into orbit. the naive intuition is that lensing hawking radiation might stabilize unstable elements for longer periods.

No, you entangle them locally and they maintain their entanglement as they move away from each other.

Re: Einstein's Other Theory of Everything

#55
post #4

Physicists didnt abandon this idea, Wheeler's geometrodynamics was all about the concept of geometry being relevant for more than grabity. As it happens with so many cool ideas it did not germinate something useful.

> As it happens with so many cool ideas it did not germinate something useful.

Well, at least, not so far.

Re: Einstein's Other Theory of Everything

#56
post #46

so, Higgs gives mass, and the mass curves the space to produce what the see as gravitation. I think there are some questions here to the Higgs at it seems it has some special relation to the spacetime. And that https://en.wikipedia.org/wiki/Black_hole_electron "...the angular momentum and charge of the electron are too large for a black hole of the electron's mass: a Kerr–Newman object with such a large angular momen…

Energy gives mass. The Higgs mechanism only explains the mass of the elementary particles (electrons, quarks, W and Z bosons, etc). The vast majority of the mass of everything else comes from the energy of the strong force or the electromagnetism.

For example, the vast majority of the mass of a proton is explained by the immense energy of the three quarks and gluons being bound together by the strong force. The mass of the quarks themselves is only a tiny portion of that (about 1%), while gluons are massless.

The mass of the atom is further increased by the energy of the electromagnetic force. A hydrogen atom has one proton (1.6726×10^-24 g) plus an electron (9.1×10^-31 g), but the mass of the hydrogen atom is slightly higher than their sum (1.6735×10^-24 g).

The mass of a composite particle is at least partly coming from the famous E = mc².

The Higgs mechanism is ultimely just a way for elementary particles to have this type of energy as well, even in a void and without any other forces present. There is nothing special about it and spacetime, it works like any other field.

Re: Einstein's Other Theory of Everything

#57
post #6

If mass/energy were interconvertible with space, if the former were some curled form of the latter, could you explain dark energy as the uncurling of mass/energy into ordinary space?

It's possibly even simpler than that. The equations of GR involve a constant, called the cosmological constant, which could be given any value without changing the theory. A positive value for that constant would exactly correspond to what we know about dark energy.

Re: Einstein's Other Theory of Everything

#58

Earlier quoted context omitted.

photons entangle at a distance as there is tech in the market right now in cryptography that uses entangled photons over distances of several miles into orbit. the naive intuition is that lensing hawking radiation might stabilize unstable elements for longer periods.

No, you entangle them locally and they maintain their entanglement as they move away from each other.

Yeah, even entangling particles remotely seems to require two pairs of entangled particles locally, sending each half somewhere, entangling the remaining local halves again locally and then using quantum teleportation to transfer the entanglement to the remote pairs together. So while you could do this to entangle a particle to a black hole, you’d still need to travel to the black hole classically and there’s no way to do this today as the nearest black hole is over 1k light years away.

I’m not aware of any theoretical or experimental way to straight up entangle unrelated particles remotely but I don’t know QM enough to say it’s straight up impossible but it would violate my understanding of how entanglement works.

That being said it is an interesting thought experiment although in practice I doubt you’d measure anything particularly interesting through the entanglement and more importantly it’s not clear entanglement would survive near a black hole since we don’t have a unified model of gravity and QM.

Re: Einstein's Other Theory of Everything

#59
post #48

Earlier quoted context omitted.

Balls on sheet is a wrong model imo. It needs gravity to work and therefore doesn't explain gravity. I like to imagine a sponge. If you could somehow make dense lumps inside the sponge (may be apply heat in its center somewhere using microwaves?) everything around that lump will be feel a tension/attraction towards that lump. That's my mental model.

It just needs force, no? You could use magnetism or even intertia if you accelerated the system, right?

Sure, but the problem is that the geometry of the sheet alone doesn't indicate what will happen to the matter on it; you need something external. Whereas in actuality the curvature of spacetime alone is sufficient.

Re: Einstein's Other Theory of Everything

#60
post #3

An alternative to the “ball on rubber sheet” model of gravity is “twisting a lump out of a sheet of silly putty.” You get the same curvature without relying on gravity to serve as a model of gravity (which always bothered me a bit) For clarity, here’s what I mean: if you flatten out some silly putty (or pizza dough should work) then pinch and twist together some of the sheet into a lump, that pulls along the surround…

Balls on sheet is a wrong model imo. It needs gravity to work and therefore doesn't explain gravity. I like to imagine a sponge. If you could somehow make dense lumps inside the sponge (may be apply heat in its center somewhere using microwaves?) everything around that lump will be feel a tension/attraction towards that lump. That's my mental model.

It's not trying to explain gravity. It's trying to visualize it.
Post reply on HN