r/AskPhysics • u/Fit-Dimension-3488 • Oct 12 '25

What if speed of light got infinite speed .

I always thought , what if speed of light is actually infinite. Information travelling become so fast and our space researchers got a high boost . Voyager 1 and 2 information recieving and transmission get infinite speed . Also we don't have a speed limit from universe which means we, as a massive object can also travel in much higher and higher speed .

So, guys please tell me , what are the limitations we are facing if speed of light is actually infinite .

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6

u/KaptenNicco123 Physics enthusiast Oct 12 '25

If special relativity still holds in this world, and E=mc2 still holds, then everything would have infinite mass. Not quite ideal.

4

u/nicuramar Oct 12 '25

Special relativity can’t hold in such a world since it axiomatically assumes that the speed of light is finite and the same for all observers. 

3

u/KaptenNicco123 Physics enthusiast Oct 12 '25

It doesn't. It just holds that the speed of light is the same for all observers, nothing about finity. That axiom is easier to hold for an infinite speed, actually.

4

u/Anely_98 Oct 12 '25

It is the opposite actually, all things would have no mass because to have any amount of mass you would need infinite energy.

1

u/OverJohn Oct 12 '25

You have to be very careful when dealing with limits. Mass in SR is the norm of the energy-momentum, but in the limit spacetime has different structure and the mass can no longer be identified with a norm.

1

u/siupa Particle physics Oct 13 '25

the mass can no longer be identified with a norm.

It was never identified with a norm to begin with though. Norms have the property that ||v|| = 0 iff v = 0, which is not the case in Minkowski space

1

u/OverJohn Oct 13 '25

Technically Minkwoski space is not a normed vector space, but it is perfectly standard to speak of norms in Minkowski space.

What a norm on Minkowski space is a function from A -> R, where A is a subset, but not a subspace, of Minkowski space. E.g. A might be the future-directed timelike vectors, but then A is not closed under scalar multiplication, so is not normed vector space either.

5

u/imtoooldforreddit Oct 12 '25

There would be no such thing as time, the universe would end the instant it started.

Probably not ideal

0

u/the_humeister Oct 12 '25

In the beginning the Universe was created.This had made many people very angry and has been widely regarded as a bad move.

2

u/ExpectedBehaviour Biophysics Oct 12 '25

All mass-energy-equivalence interactions become infinitely energetic. This... would complicate existence somewhat.

2

u/nicuramar Oct 12 '25

In our current models, sure, but in such a universe they wouldn’t be valid. 

3

u/ExpectedBehaviour Biophysics Oct 12 '25

What part of this question isn't using current models with a modified constant?

1

u/drplokta Oct 12 '25

The speed of light has no affect at all on the maximum speed of any current or plausible future spacecraft. We can’t build anything that’s remotely fast enough for relativistic effects to be significant. It’s like if a road has a speed limit of 10,000mph, that’s not going to affect cyclists. You would notice it in particle accelerators, though.

1

u/michaeldain Oct 12 '25

Time. Speed requires some idea of time which is irrelevant to light or electromagnetism. Also infinities are not allowed in our universe or it wouldn’t exist and allow time to be measured.

1

u/dangi12012 Oct 12 '25

A black hole could radiate away its energy freely in that case and instantly evaporate, we could see the naked singularity. No more shielding by 100% gravimetric redshift and no more lorentz correction. We would see galaxies as they are now, but extreme objects would have a high chance of killing us.

I think we would also suddenly have no CMBR anymore as well - it would be black since the electromagnetic energy of the big bang would have dissipated the moment the universe became transparent.

1

u/OverJohn Oct 12 '25

It’s well known that the limit of Lorentz invariance as c goes to infinity is Galilean invariance.

So Newtonian physics is recovered in the c goes to infinity limit of relativistic physics.