# Time and distance: light-second

Dear Tom and Ray, In your recent show you equated a listeners’ odometer miles to the distance between the earth and the moon which as you know is not constance. A more relative measure is a “light second” at 186,000 miles per hour. So when a vhicle travels a light second, it’s time to rotate the air in the tires. Miles and meters are so earth bound, univeral speed is the way to measure things! So a vehicle travels 264000 nano light seconds at 5 miles per hour. Or something like that… Love the show.

Speed of light 186,000 miles per SECOND not hour. Light second=distance light travels in one second.

Right 186000 miles is equal to one light second. So a nano light second is 10 E-9 miles or .000186 miles in one second or .6696 miles in one hour (times 3600). 26.4 nano light seconds equals about 17 miles per hour. (i was off by a couple of wave lengths)

NO. No. No. NO number of lightseconds equals any number of miles per hour. You simply cannot mix units like that. Please step away from the keyboard.

“the moon which as you know is not constance”

I have always referred to the moon as Emily, but your family may have referred to that heavenly body by a different name.

;-))

Like the others said, light-second is a unit of length (186,000 miles), not velocity. Coincidentally, a nano light second is equal almost exactly to one foot! (11.8 inches, to be more exact).

So 5.8 K nanoLight seconds = 1 mile therefor 300 K nanolight seconds is ~ 50 miles and 300K nanolight seconds is 50 miles per hour. If you are measuring velocity, but the questions were odometer reading in relation to the distance to the moon. That distince is changing. But a light second, 186000 miles is a constant distance.

“therefor 300 K nanolight seconds is ~ 50 miles and 300K nanolight seconds is 50 miles per hour”

How do you do that? If 300K nano light seconds is ~ 50 miles, then it’s not 50 miles per hour, right?

It’s 50 miles. If you travel thta distance in one hour, it’s 300k nanolight seconds per hour. As pointed out above its a distance not a time but a constant distance.

OK, then you should have said “therefor 300 K nanolight seconds is ~ 50 miles and 300K nanolight seconds traveled in an hour is 50 miles per hour”

Rear Admiral Grace Hopper, a computer pioneer, used to hand out “nanoseconds” at her lectures - wires cut to just over 11 inches.

I stand adjusted. I was mixing terms trying to create a speedo that was calibrated to a light-second.

A light nanosecond is a speed times a time, which becomes a distance. We don’t calibrate distances on a speedometer. Those are reserved for odometers.

A light second is 186,072 miles (in a vacuum anyway).

We could calibrate a speedometer in terms of the speed of light (referred to as “C”, just as military interceptor jets have mach indicators referenced to the speed of sound. Such a speedometer, instead of reading 50 Miles per hour would read 7.46426 * 10^-8 C. Not a reading that would be ready meaningful to most people, which is probably why we stick to miles per hour.

If my airspeed was indicating 50mph ,well I would scan some of the other gagues,maybe check my harness (bailout time).