Reply To: Iconography

[meemoe_uk]

Ein = P t
Eout = 0.5 m v^2
= 0.5 m a^2 t^2
= 0.5 m (F(P)^2 / m^2) t^2
= 0.5 (F(P)^2 / m) t^2

Eout / Ein = ( 0.5 F(P)^2 / ( m P) ) t
= k t

OU occurs for all t > 1/k

Therefore all propellantless propulsion schemes, whereby the motive force is a function of the on-board power, are inherently OU after some characteristic time T

A pertinent question to understanding the em drive :

Why, if when you shoot a 100W laser, are you not pushed back with an equal and opposite thrust equivalent to 100W ?

My answer : photons have very low momentum for the amount of energy they carry, therefore the push back from a 100W laser is negligible.

The point is, as a propellant, a photon is a vast untapped stash of energy. Using them as a propellant is like jettisoning fuel tanks.
Is there a way of converting the energy of a photon into momentum ? This is one of the motivating questions which led to the em drive.

The question also illustrates we already know kinetic energy equations alone aren’t sufficient to explain conservation of energy wrt light, particularly non-relativistic analysis with kinetic energy. Along similar reasoning to Andrew’s analysis and conclusion, light doesn’t exist since the energy used to make photons isn’t accounted for in his non-relativistic kinetic energy equation.

Converting between one form of energy to another should not be a taboo for physicists, so don’t be so quick to dismiss it with a napkin of non relativistic college level physics. Any attempt to understand conservation of momentum and energy in a system involving both light and mass is going to fail if the analysis is non relativistic.

Anyway, here’s another question that should pique interest in the heart of any physicist.

Is the doppler shift reversible?
I don’t mean blueshift as opposed to redshift. I mean: since red shift is caused when an object changes velocity, is a change of velocity causable by red shift?

According to Roger Shawyer, yes. We know for sure the maths works because we already have motion causes redshift maths. Every equation used to theorise the EM drive has already been used to describe doppler red shift.
The argument against the EM drive then becomes : is there a “trap door” aspect to doppler maths, so that it works “motion to red shift”, but not “redshift to motion” ?.
I haven’t read about any such trap door, either in maths analysis or otherwise.

The trick of the EM drive is that its captures red shift in a bottle, which should appeal to Eric since thats what he’s done with quasars with FoFu1.