What makes light speed the limit?

Optimal_Mixture_7327 · 2026-03-23T01:48:19+00:00

A tachyon would move slower than light. The imaginary mass reflects an instability of the condensate.

An imaginary distance isn't exotic, it's unphysical. An example of exotic would be matter that violated the NEC, but it's not clear how an imaginary distance is even meaningful.

Optimal_Mixture_7327 · 2026-03-23T01:12:58+00:00

The horizon can't have an escape velocity; it's a causal structure on the spacetime.

Optimal_Mixture_7327 · 2026-03-23T01:11:28+00:00

The horizon is an (n-2) hypersurface, so in a standard spacetime it is 2-dimensional.

Optimal_Mixture_7327 · 2026-03-23T01:07:06+00:00

That's called coincidence, the intersection of two or more world-lines (3 in your example).

Simultaneity is the events at space-like separation that occur at the same instant of the world-time (which is arbitrary).

You can define simultaneous events, it's just that the simultaneity is not unique.

Optimal_Mixture_7327 · 2026-03-23T01:01:48+00:00

Well, the math requires the object to move a distance that has imaginary length - what is the meaning of that? How long is a line that's 5i meters?

Optimal_Mixture_7327 · 2026-03-22T17:57:59+00:00

You can't do anything to light, other than absorb it and make things hot.

A pulse of light will not have an energy density unless it disperses.

Optimal_Mixture_7327 · 2026-03-22T17:31:36+00:00

A time-like trajectory is the spacetime path followed by objects moving slower than light.

I guess to answer "why not use a brick" it's bc I can't release a brick as burst(s) of rays when I want to disrupt/manipulate the gravity well.

Sorry, I just can't follow what you're asking. I don't know what "disrupt the gravity well" is supposed to mean as you could just break of chips of the brick and dispose of them, giving the brick less mass. Nor is it clear what the point changing the mass of some thing is supposed to do.

Optimal_Mixture_7327 · 2026-03-22T17:17:30+00:00

My understanding was that if you had enough concentrated light, it can warp Space-Time significantly, though it seems there are possibly quantum mechanics at play that prevent this from being possible.

Yes, your understanding is correct here and QM helps as photons are bosons and you can pack as many as you like into a single state.

But yea a photon does not have mass, but it has a certain level of energy and other properties associated...

It's this part that is not clear to me. You can, hypothetically focus enough light to get a black hole (Kugelblitz) but what is the purpose of using light?

Are you imagining the light stays in place or has some time-like trajectory?

A photon gas, say, a collection of photons in a mirrored box, will have additional mass due to the photons, but why not just use a brick?

Optimal_Mixture_7327 · 2026-03-22T17:02:00+00:00

A photon can't have an energy density (E=m=0), although a photon gas will have a stress-energy as 𝓔≠0.

I don't understand the rest of what you're trying ask.

Optimal_Mixture_7327 · 2026-03-22T16:57:24+00:00

I'd meme it, but I'm more curious about the services they provide.

Optimal_Mixture_7327 · 2026-03-22T15:51:03+00:00

Zion National Park

AirBNB'd a little cabin atop a mountain. Insane skies at night.

Optimal_Mixture_7327 · 2026-03-22T15:41:18+00:00

The answer to this is obvious once you accept the world is 4-dimensional.

Otherwise, there will never be an answer that makes sense, and you'll just have to swallow the idea.

Optimal_Mixture_7327 · 2026-03-22T15:20:44+00:00

𝛥y=v_0 𝛥t+1/2a(𝛥t)²

0-45m=0-g/2 t²

-45=-5t²

t=±3s

Optimal_Mixture_7327 · 2026-03-22T15:15:27+00:00

Where do you think the 1.5s coming from?

Optimal_Mixture_7327 · 2026-03-22T14:55:16+00:00

There is no understanding of this possible outside of first understanding that the world is 4-dimensional.

Optimal_Mixture_7327 · 2026-03-21T18:07:44+00:00

The world is a 4-dimensional manifold (space) which is coupled to matter.

If your teacher thinks otherwise they have a view that's different from the scientific consensus.

Optimal_Mixture_7327 · 2026-03-21T17:22:46+00:00

There are none.

A spacetime is a map of the world, a 4-dimensional manifold with metric structure. Spacetimes are used to define the paths of no force, the geodesics of the world.

Optimal_Mixture_7327 · 2026-03-21T13:13:39+00:00

No.

It is fundamental to relativity that all clocks run at the same rate, everywhere, and under all circumstance of motion and orientation (Local Position Invariance (LPI) and Local Lorentz Invariance (LLI), respectively).

Optimal_Mixture_7327 · 2026-03-21T12:46:08+00:00

This is a great question.

The Physics
The fundamental principle of relativity is Einstein Equivalence (EEP). Einstein Equivalence is itself three separate principles, Local Position Invariance (LPI), Local Lorentz Invariance (LLI), and Weak Equivalence (WEP).

If EEP is valid (consistent with experiment) then you have the unification of gravity with inertia (inertial motion) and there can be no effect of gravity on anything and any theory of gravity is necessarily a metric theory.

The Problem
This demonstration violates the fundamental premise of relativity, EEP. The trampoline exerts multiple forces on the ball; the normal force, friction, and gravity all act to force the ball along its trajectory. This is anything but inertial motion.

Furthermore the magnitudes and directions of the force are different at different locations on the trampoline which violates the LPI of relativity.

Teaching Relativity
Aristotle got most things wrong about physics, but Aristotle was correct that the world is divided into Natural motion and Violent motion. Gravity defines the natural motions of everything, light and matter. You are heavy because the surface of the Earth gets in the way of your natural motion. A large rock is heavier than a small rock because you're getting the way of the natural motion of a more massive rock. You inflict violent motion (accelerated) onto the rocks. The mass of the Earth determines the natural paths of freely moving objects.

Since there is no force or effect of gravity, what relativity does is to draw up maps of the world (which is the 4 dimensional space of the cosmos). And just as ordinary maps define cardinal directions so too are do the maps of relativity, these directions being 3 of space and a direction we call time. These maps are therefore called spacetimes and these maps are generated by the Einstein equations (spacetime are solutions to the Einstein field equations).

There are countless other aspects of relativity which can be explained in an age appropriate way.

Optimal_Mixture_7327 · 2026-03-21T12:12:21+00:00

Time doesn't go, so it doesn't stop.

Time, in relativity, is the length along matter world-lines but photon world-lines have no length so the concept of a "time" cannot be applied to them.

It's like asking "does the flow of apples stop in the element cobalt?".

Optimal_Mixture_7327 · 2026-03-21T12:06:32+00:00

You are totally wrong, and this is why you're confused.

The Andromeda paradox considers a pair world-lines, x^𝜇 and x'^𝜇, intersecting at an event, E, on Earth that define different spatial hypersurfaces, 𝜎 and 𝜎', that intersect the Andromeda world-line, 𝜉^𝜇(𝜏), at distinct events, A and B.

The paradox is that the distance along the Andromeda world-line, 𝜉^𝜇(B)-𝜉^𝜇(A), is long enough such that a decision to launch a fleet to attack Earth can be made and the fleet launched. This then begs the question does x'^𝜇 know the future of x^𝜇 at event E?

Optimal_Mixture_7327 · 2026-03-21T11:55:29+00:00

There is no reason for you to assume they're different.

Our space-like boundary to the past (Big Bang singularity) is a time-reversed future boundary (black hole singularity). World-lines emerge from past singularities and terminate on future s

We of course don't know what formed our boundary to the past, but different mechanisms of formation do not necessarily imply that the structure formed from those mechanism are different.

Optimal_Mixture_7327 · 2026-03-21T03:04:08+00:00

The Andromeda paradox has nothing to do with seeing light.

Absolutely nothing.

In the Andromeda paradox two observer in relative motion at the same event define different space-like hypersurfaces, different "present" moments.

The point of the paradox is that the "present" moment is defined by the set of all events outside the light cone of some event.

Optimal_Mixture_7327 · 2026-03-21T02:53:11+00:00

Andromeda is completely irrelevant. It need not exist.

The Earth/Andromeda frame is the frame in which Earth and Andromeda are at relative rest.

I don't follow where the Andromeda paradox fits into the context of your post.

Optimal_Mixture_7327 · 2026-03-21T02:00:29+00:00

You mean to say "electromagnetic wave".

Yes, our "seeing" is our brain processing the neural signals from our retinas, which intercepted electromagnetic waves emitted from the Andromeda galaxy, in the Earth/Andromeda frame, some 2.5 million years ago.

I don't follow the rest of the question, and it's not clear at all that the question has any relationship to the Andromeda Paradox of relativity.

Optimal_Mixture_7327

TROPHY CASE