What is spacetime?

[Walker]

If atoms could travel at the same speed as photons, there would be no exchange because the photons would be using all their velocity just to keep up, nothing would happen. You wouldn't notice though, because nothing would happen between yours ears either.

Setting aside the claim that no material object can travel at the speed of light,...

(see my speculative reason for that here: https://www.ilovephilosophy.com/t/tuggi ... wo%20of%3A)

...how do you get the notion of "...nothing would happen between your ears..." to square with the fact that according to Special Relativity, everything (including the passing of time) would still appear to be normal from the perspective of the person traveling at the speed of light?
_______

I would assume if we were traveling at the speed of light and a neuron sent a signal to another neuron in the brain that was 'upstream' from it, the signal would never reach its destination. Conversely, if a neuron sent a signal to a neuron 'downstream', I would think the signal would arrive instantaneously. No?

If you were going that fast your mass, that at times feels infinite, actually would be.

[Walker]

Earth time is rotational.

Remove the rotating earth and space time is vibration, measured by free-floating atomic clocks.

[Skepdick]

Let's say Planck time, the last sediment of the past?

Why? Planck time is just the limit beyond which quantum-gravitational effects become non-negligible. It's the practical limit of our current theories, not a fundamental discretization of time.

I don't know, but it is clear that elementary particles, molecules, DNA, but also the alphabet, words, logical statements or even eigenvalues of wave functions... are discrete.

Sure. You keep calling them "discrete", but you can call them anything.

Looking for, extrapolating something, between them is unproductive...

That's weird. I thought those were reductions/isolates (from the continuous whole), not extrapolations.

We don't extrapolate continuity from discreteness; we extract discreteness from continuity

[Will Bouwman]

...how do you get the notion of "...nothing would happen between your ears..." to square with the fact that according to Special Relativity, everything (including the passing of time) would still appear to be normal from the perspective of the person traveling at the speed of light?
_______

The thing is, as Gary Childress points out, there will be nothing happening in your brain because it is a physical object and like all physical objects it is subject to time dilation. So your brain activity slows down by exactly the same amount as everything else that is happening, so everything appears completely normal to you. From a point of view outside your very fast moving inertial frame, you would appear to be doing everything very slowly. That you would see everything happening slowly in the observer's inertial frame is only true in the special conditions of special relativity, according to which two inertial frames flash past each other and continue in a straight line, never to meet again. Check out the final chapter for how general relativity allows different observers to see different time dilation: http://willybouwman.blogspot.com/2024/0 ... n.html?m=1 Having said all that, if there is some extra-cerebral component to consciousness, mind, spirit or soul perhaps, I have no idea how it would respond to relativistic velocities.

[Impenitent]

what if reaching the speed of light is only achieved by having exactly zero mass?

-Imp

[Cerveny]

Why? Planck time is just the limit beyond which quantum-gravitational effects become non-negligible. It's the practical limit of our current theories, not a fundamental discretization of time.

I don't know, but it is clear that elementary particles, molecules, DNA, but also the alphabet, words, logical statements or even eigenvalues of wave functions... are discrete.

Sure. You keep calling them "discrete", but you can call them anything.

Looking for, extrapolating something, between them is unproductive...

That's weird. I thought those were reductions/isolates (from the continuous whole), not extrapolations.

We don't extrapolate continuity from discreteness; we extract discreteness from continuity

A real thing can't be infinitely fine, I think. What would it be made of? Nothing?

[Skepdick]

A real thing can't be infinitely fine, I think. What would it be made of? Nothing?

These are meaningless questions outside of a reductionist framework.

Things aren't "made of" anything. That's just your substance metaphysic asking faulty questions.

[Phil8659]

What is spacetime?
Everything in SRT, GRT and quantum mechanics is done in so-called "space-time",
which is a kind of virtual 4D geometry.
But if SRT is correct and if QM is the basis for successful modern technology,
then space-time cannot be a virtual, abstract structure.
Space-time must be a real structure, real a frame of reference.
What is it? ....
1) Everything exists in the infinite, eternal, flat, cold cosmic vacuum. ...
2) Only in the cosmic vacuum are space and time one inseparable system (as is space-time) ...
3) One of Einstein's special relativity states: the speed of light in a vacuum is
constant and independent (as in space-time) ...
4) Dirac's formula E= ± mc² belongs to the system of "vacuum sea" ...
Spacetame is the cosmic vacuum.
‘'The problem of the exact description of vacuum, in my opinion, is the basic problem
now before physics. Really, if you can’t correctly describe the vacuum, how it is possible
to expect a correct description of something more complex?'' /Paul Dirac/
Book ''The Fermi Solution'':
''. . . something seems wrong with our idea of the vacuum. It is we who abhor a vacuum,
who recoil from the stillness of the void as from an open grave.''
/page 37-38, by Hans Christian von Baeyer /

Everything you have stated, is factually nothing more than words pasted together by the illiterate.
Space is a relative difference which means one can parse it to make things. Time is a relative difference, which means you can parse that to make things, but no one but an illiterate moron can predicate one of the other, or combine them like a blanket. Your 4D geometry is a myth. Geometry like every other grammar is simply a method of utilizing binary recursion by a particular standard, being a one to one correspondence of the physical with the intelligible binary.
The speed of light is an oxymoron if you then claim that it is the same as a relative difference and not the speed of some one thing. We might say, the speed of photon's, or the speed of an atom, etc., but light is a perceptible metaphor, i.e., it is not even a grammatically correct use for science.

[Cerveny]

A real thing can't be infinitely fine, I think. What would it be made of? Nothing?

These are meaningless questions outside of a reductionist framework.

Things aren't "made of" anything. That's just your substance metaphysic asking faulty questions.

I think logic is absolutely relentless in this matter. Infinitely fine matter is by its very nature composed of infinitely small parts, i.e. points, i.e. nothing. Or perhaps a point (intended) can have, carry some real physical property (i.e. apart from specific mathematical coordinates)

[Skepdick]

A real thing can't be infinitely fine, I think. What would it be made of? Nothing?

These are meaningless questions outside of a reductionist framework.

Things aren't "made of" anything. That's just your substance metaphysic asking faulty questions.

I think logic is absolutely relentless in this matter. Infinitely fine matter is by its very nature composed of infinitely small parts, i.e. points, i.e. nothing. Or perhaps a point (intended) can have, carry some real physical property (i.e. apart from specific mathematical coordinates)

That's just metaphysical nonsense. Projected onto reality.

The map is not the teritory.

[Will Bouwman]

what if reaching the speed of light is only achieved by having exactly zero mass?

-Imp

Well, in such a crazy universe, everything would look pretty much as it does in this one.

NB. Yeah, technically that's exactly zero rest mass. Photons have energy and therefore, because of the mass/energy equivalence, they have mass, but only if they're moving. Then again, a photon that isn't moving just isn't a photon, it's just a spludge of energy that exists in the cloud of energy that is an atom. Or quantum field. Or something. Anyway, it isn't a photon.

[Walker]

what if reaching the speed of light is only achieved by having exactly zero mass?

-Imp

Then speed yields to instantaneous* because without the (electron) baggage, photons are phaster than Teslas.


*Light years are for those left in the dust.

[Impenitent]

recombining mass after it achieves light speed could be tricky...

ships of Theseus everywhere

-Imp

[Will Bouwman]

Yer not wrong. Good job it's impossible, cos I'm pretty certain it would be fatal.

[Walker]

recombining mass after it achieves light speed could be tricky...

ships of Theseus everywhere

-Imp

Well, it only seems logical that if we can imagine an entity with infinite mass scorching through the universe that it is, because it swallowed the universe, then just imagine a solipsistic photon’s perspective, existing outside of time, perceiving the Alpha as the Omega by simultaneously existing here and there because of no mass, never moving because movement is within time. Kinda God-like, this photonic entity and in comparison, those left in the dust particle mass are forever between here and there in the galactic scale.

"No mas, no mas!" - Roberto Duran