1 mach / in kmh

light has zero rest mass but contributes to the inertia (and weight in a gravitational field) of any system containing it.

 

Inertia is one of the primary manifestations of mass.

 

A photon moving at the speed of light has a mass of 1x10^-18 electron volts.

 

Given that practically, you will never meet a stationary photon, all the photons you ever meet will have a non zero mass of about 1E-18 EV

 

 

That was how it was incorrectly explained to me - the actual reason is here:

https://en.wikipedia.org/wiki/Crookes_radiometer#Explanations_for_the_force_on_the_vanes

 

That the phenomena does exist as I explained it is explained here:

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

 

This has drifted OT though, so I'll stop :)

You're confusing me. Electron volts is a measurement of energy, not mass. They are related but not interchangeable.

The Wikipedia article states it is a heat engine and explains it with heat and radiation, I find nothing about it being related to photons having mass.

"The air pressure inside the bulb needs to strike a balance between too low and too high. A strong vacuum inside the bulb does not permit motion, because there are not enough air molecules to cause the air currents that propel the vanes and transfer heat to the outside before both sides of each vane reach thermal equilibrium by heat conduction through the vane material"

If you were right that there was a transfer of kinetic energy or inertia then it should work in a perfect vacuum as well.

Discussing the photon having mass or not might be considered a slight thread drift from ”Why does mach 1 only read 1270 kph” :)

 

Most common explanation to black holes is that gravity is so strong that even the light cant overcome it.

You're confusing me. Electron volts is a measurement of energy, not mass. They are related but not interchangeable.

Energy and mass are simply different phases of the same thing.

At the beginning of the big bang, there is no matter, only energy. Only when the energy density gets low enough can matter 'precipitate' out of that energy field.

The energy released by a fission, or fusion bomb is the result of some matter being turned into energy.

That's what the equation E=MC^2 describes

Re-arrange it to M = E/C^2 & plug the energy value above converted to Joules in where the E is.

The problem is if you use kg, you get a tiny, tiny (but non-zero) mass, so eV are used to describe the mass of sub-atomic particles because they give more meaningful numbers.

Re the reference to crookes radiometer.

Please re-read my post. I say that the radiometer isn't driven by momentum, and to look to the second link for a description of an effect that is:

Radiation pressure is the pressure exerted upon any surface due to the exchange of momentum between the object and the electromagnetic field. This includes the momentum of light or electromagnetic radiation of any wavelength which is absorbed, reflected, or otherwise emitted (e.g. black body radiation) by matter on any scale (from macroscopic objects to dust particles to gas molecules).

the SI unit for momentum is kg⋅m/s

Zero mass = zero momentum.

Non-zero momentum = non-zero mass.

Light produces a pressure due to the exchange of momentum, therefore light must have a mass (and I gave you the mass of a photon in eV earlier)

Edit: any other questions maybe PM me.