I Effects of time dilation for near-speed-of-light travel

[Chenkel]

Why not just pick up a book about relativity and study it? I can recommend the book by Morin "Special Relativity: For the Enthusiastic Beginner" which is quite cheap.

Thanks for the reference, I'll check it out!

 

[jbriggs444]

Light speed is also approximately one foot per nanosecond.

Grace Hopper used to hand out nanoseconds at her lectures. (one foot wire segments). The one time I heard her speak, wire was too expensive and I picked up a salt packet of picoseconds instead. (Google says pepper. I remember salt. Go figure).

 

[robphy]

Grace Hopper used to hand out nanoseconds at her lectures. (one foot wire segments). The one time I heard her speak, wire was too expensive and I picked up a salt packet of picoseconds instead. (Google says pepper. I remember salt. Go figure).

Go to t=46m00s [for milliseconds... start at t=45m07s]



About Adm Hopper


https://en.wikipedia.org/wiki/Grace_Hopper

 

[PeterDonis]

Why do some people write c = 1?

Because they're using units called "natural units" in which $c = 1$.

Why do some people write c = 299792458 meters per second?

Because they're using SI units, in which ##c# is defined to have that value.

I'm not sure what the issue is with this. Surely the existence of multiple different systems of units is no mystery.

Does the 1 in the expression "c = 1" represent one light second per second?

It can. Or it can mean one meter per light-meter (meter of light travel time). Or it can mean one light year per year. The point is that the unit of distance and the unit of time are related by the time it takes light to travel the distance. That makes things much simpler mathematically (you don't have stray factors of $c$ all over the place and have to worry about whether you've gotten them all right) and makes spacetime diagrams easier (because the worldlines of light rays are 45 degree lines and the units on both the space and time axes are the same).

 

[PeterDonis]

My last reply just talked about treating Lorentz factor as an infinite hyperreal, not sure if this can be done

No, it can't. There is no such thing as an inertial frame in which a photon is at rest.

 

[Chenkel]

Why not just pick up a book about relativity and study it? I can recommend the book by Morin "Special Relativity: For the Enthusiastic Beginner" which is quite cheap.

It is hard (impossible) to learn a new subject on a forum.

I got the book recently and I've been studying it, it's interesting so far and I think I'll learn a lot from it.

Thank you for the suggestion