[blamestross]

I like that somebody called out that there is a lot of misinformation/crap around relativity and the speed of light.

The article points out that mass doesn't increase with velocity.

The next big lie is that nothing can go faster than the speed of light. One thing can: Me (or you from your point of view). The whole time dilation thing only happens to other things/people. I can accelerate to any velocity. The universe just won't let me observe anybody else going faster than the speed of light. It doesn't change the fact that I can accelerate well past c and get to alpha centauri as soon as I am willing to expell propellant for. It's only everybody else time will do wonky things for.

[jjtheblunt]

I'm curious why you write what you wrote: at Fermilab, where some high school students took physics including from a Nobel laureate, I remember (as a high school student) that the problem with exceeding the speed of light, from the point of view of a reference frame, is that, if

e = mass * celeritas^2 / Sqrt( 1 - velocity^2/celeritas^2 )

describes relativistic mass and energy conversion, where i spelled out c as celeritas as the speed of light, at least in the reference frame, something implausible is implied.

Looking at that equation, as an object's velocity approaches the speed of light, the denominator approaches zero, and the equivalent energy of the moving mass goes towards infinity.

That led to the quandary : can you really get something to go that fast?

(I'm on a keyboard with no paper to fiddle with, or I'd further monkey with the equations.)

[blamestross]

From the outside perspective that is mostly true.

The flaw is that you don't gain mass as you go faster. You gain momentum. That momentum energy even causes gravity in a way[1].

The reason it seems to take infinite energy to go faster than light is that the rate of time for the traveler changes as they go faster. From your observer's perspective, whenever they accelerate the speed increase is exactly cancelled out by the change in relative time rates. The more energy they spend the faster they go, but never quite fast enough to go at C.

From the traveler's perspective it is a totally different adventure. When they add energy they accelerate. Period. They don't notice the time dilation outside of observations of their origin and destination. If they have enough fuel, they can accelerate smoothly to 2 times the speed of light and travel a light year in 6 months. The problem is that more than a year will have gone by in the origin and destination on the way and they were never observed going faster than C.

If we had a way around the rocket equation we could easily cross the Galaxy within a human lifetime. It would just be Earth would be gone by the time we got there.

[1]https://physics.stackexchange.com/questions/63961/does-relat...

[mikewarot]

In fact, if you see light from 10 billion light years away, as far as the photon is concerned, it just left, traveled for zero time, and hit your eyeball.

[ErotemeObelus]

> One thing can: Me (or you from your point of view). The whole time dilation thing only happens to other things/people. I can accelerate to any velocity.

You can't go faster than the speed of light in your reference frame because you are always doing zero in your reference frame.

[blamestross]

Sure, but I can go from location A to location B in a duration shorter than their distance in light-seconds.

The universe just hiccups a bit and decides to move the destination towards me and origin further way because i'm not allowed to see my destination travel towards me faster than light or my origin recede faster than light.