Why Can't Anything Travel Faster than Light?

[Rhondazvous]

Thank you . Probably not necessary, but just to hammer this home: another way to picture the difference is to imagine being in freefall on the ISS. You are weightless, so you float around the cabin. But smacking into the bulkhead is the moment you become aware of your mass.

And that is the moment I become aware that I have a nervous system while the bulkhead does not.

---

[...] since in a vacuum where there is no gravity

Just wanted to say, there is indeed gravity in a vacuum; that's why the Earth orbits the Sun, why galaxies coalesced, etc.

Touché since I am at fault for not making myself clear. By vacuum I mean outside the gravitational pull of any other object. In practice it may not be possible to be in such a place, but I'm speaking theoretically/hypothetically/rhetorically.

[Alex K]

Basically, yeah. The abovementioned fact that the speed of light is always the same has as a direct consequence that your time would have to stand still if you're going at the speed of light.

Doesn't that create a paradox or at least an infinite loop? If time stands still at c then v = 0. which means m is not traveling at c so time doesn't stand still meaning that m is traveling at c where time stands still and v = 0, ad infinitum.

So, yes in a sense taking the limit of v=c as an observer is not a mathematically consistent thing to do and you encounter things like 0*infinity that by themselves aren't meaningful. But you also have to be careful how you define the velocity v - the velocity of photons being c is measured in the time frame of the observer, not of the photon.
Every object is at rest from its own perspective, and to square that with lightspeed always being c leads to the extreme ( and not quite mathematically consistent ) limiting case of time stopping. Then from the photons perspective, it doesn't move but also no time passes, so the speed is 0/0. This tells you that the vantage point of the photon isn't really a mathematically valid reference frame.

[bennyboy]

Basically, yeah. The abovementioned fact that the speed of light is always the same has as a direct consequence that your time would have to stand still if you're going at the speed of light.

Doesn't that create a paradox or at least an infinite loop? If time stands still at c then v = 0. which means m is not traveling at c so time doesn't stand still meaning that m is traveling at c where time stands still and v = 0, ad infinitum.

Because from the photon's "perspective" it's not traveling-- it's just a singularity connecting two distant atoms (from our perspective). Also, /0 is fun!

[Rhondazvous]

Doesn't that create a paradox or at least an infinite loop? If time stands still at c then v = 0. which means m is not traveling at c so time doesn't stand still meaning that m is traveling at c where time stands still and v = 0, ad infinitum.

So, yes in a sense taking the limit of v=c as an observer is not a mathematically consistent thing to do and you encounter things like 0*infinity that by themselves aren't meaningful. But you also have to be careful how you define the velocity v - the velocity of photons being c is measured in the time frame of the observer, not of the photon.
Every object is at rest from its own perspective, and to square that with lightspeed always being c leads to the extreme ( and not quite mathematically consistent ) limiting case of time stopping. Then from the photons perspective, it doesn't move but also no time passes, so the speed is 0/0. This tells you that the vantage point of the photon isn't really a mathematically valid reference frame.

"Every object is at rest from its own perspective"
Except the brain of a field theorist which can single-handedly keep the Tylenol industry in business for several decades.

If no time passes, how can light have a speed? It would already be whereever it's going. The very idea of going somewhere implies a time

[ErGingerbreadMandude]

What I can never figure out for the love of God is how in the hell is a photon which apparently has no mass unable to travel from point a to point b in 0 time..

[Alex K]

So, yes in a sense taking the limit of v=c as an observer is not a mathematically consistent thing to do and you encounter things like 0*infinity that by themselves aren't meaningful. But you also have to be careful how you define the velocity v - the velocity of photons being c is measured in the time frame of the observer, not of the photon.
Every object is at rest from its own perspective, and to square that with lightspeed always being c leads to the extreme ( and not quite mathematically consistent ) limiting case of time stopping. Then from the photons perspective, it doesn't move but also no time passes, so the speed is 0/0. This tells you that the vantage point of the photon isn't really a mathematically valid reference frame.

"Every object is at rest from its own perspective"
Except the brain of a field theorist which can single-handedly keep the Tylenol industry in business for several decades.

If no time passes, how can light have a speed? It would already be whereever it's going. The very idea of going somewhere implies a time

The time base used to measure light speed is always that of the outside observer, where time passes as usual...

[LastPoet]

This reminds me of an old joke. 3 guys were discussin what isthe fastest thing...

One says, the fastest thing is human thought.
The second says the fastest thing is light.

The third says its diarhea. One doesn't have time to think or turn on the light.

[Alex K]

This reminds me of an old joke. 3 guys were discussin what isthe fastest thing...

One says, the fastest thing is human thought.
The second says the fastest thing is light.

The third says its diarhea. One doesn't have time to think or turn on the light.

Diarrhea Schmiarrhea. You haven't seen my blitzkrieg projectile vomiting performance a few weeks ago. That wall didn't even see it coming.

[Rhondazvous]

"Every object is at rest from its own perspective"
Except the brain of a field theorist which can single-handedly keep the Tylenol industry in business for several decades.

If no time passes, how can light have a speed? It would already be whereever it's going. The very idea of going somewhere implies a time

The time base used to measure light speed is always that of the outside observer, where time passes as usual...

Then to say no time passes for the photon, the observer must be able to see things from the photons pov. Is this the case? Or is this just a dichotomy between observation and mathematical calculation that makes us think the photon sees things differently?

---

This reminds me of an old joke. 3 guys were discussin what isthe fastest thing...

One says, the fastest thing is human thought.
The second says the fastest thing is light.

The third says its diarhea. One doesn't have time to think or turn on the light.

Diarrhea Schmiarrhea. You haven't seen my blitzkrieg projectile vomiting performance a few weeks ago. That wall didn't even see it coming.

You'll win a Newtonian/Einstein Noble prize if you can formulate a theory for why bills travel through the mail faster than checks.