Wow that is fascinating. I don't understand how they can not have an idea as to why it works. Seems like the original proponent of the idea would have had some basis to believe that it would work.

tigersofjustice said:

Wow that is fascinating. I don't understand how they can not have an idea as to why it works. Seems like the original proponent of the idea would have had some basis to believe that it would work.

Click to expand...

I saw someone's summary and roughly they said it went like this

Random guy: I've designed an awesome EM propulsion system.
NASA: Your design is crazy. Go away.
China: Hey, can we see that?
China: Check it out, it work!
NASA: No way...but, uh, can we see that?
NASA: OK. We'll admit it works, but we still don't believe it's why you think it works.

I ran across a good writeup. https://www.reddit.com/r/Futurology/comments/34cq1b/the_facts_as_we_currently_know_them_about_the/

I don't understand the difference between phase velocity and group velocity, but I'm a little familiar with radiation pressure and it seems there's reason to doubt the quantum physics explanation of the one drive, but I don't know that the radiation pressure explanation is even a stretch.

NIST measured 3.5 micro newtons on a mirror reflecting a 530 W laser. so 150 MW/N

The EmDrive got 3,300 W/N, and 1,000 W/N in two other tests. So it's delivering 1,000 times the radiation pressure you get when you reflect a laser off a mirror.

Is the laser setup somehow inefficient? Or is something else going on.

Unexplainable thrust propulsion

Gulo Blue said:

I ran across a good writeup. https://www.reddit.com/r/Futurology/comments/34cq1b/the_facts_as_we_currently_know_them_about_the/

I don't understand the difference between phase velocity and group velocity, but I'm a little familiar with radiation pressure and it seems there's reason to doubt the quantum physics explanation of the one drive, but I don't know that the radiation pressure explanation is even a stretch.

NIST measured 3.5 micro newtons on a mirror reflecting a 530 W laser. so 150 MW/N

The EmDrive got 3,300 W/N, and 1,000 W/N in two other tests. So it's delivering 1,000 times the radiation pressure you get when you reflect a laser off a mirror.

Is the laser setup somehow inefficient? Or is something else going on.

Click to expand...

I'm wondering if the wavelength of the laser might yield a potential explanation, as well as the mirror, but I'm just guessing. Just envisioning the photons becoming a little scattered passing through the medium of the mirror, the result being energy dissipation in perpendicular directions to the thrust. As for the wavelength, it seems a shorter one might result in more thrust as each crest hits the target. Since shorter wavelength beams require more energy to produce, they similarly would seem to pass more energy onto the target.

Just pure guesses, feel free to invalidate as I'm more likely wrong than right about these. It seems unlikely these causes could account for the high difference in performance.

I'm trying to wrap my head around the causes for acceleration, but I don't feel bad since the top scientists cannot explain it.

Maybe there is a vibrational difference from cone tip to base that is somehow causing everything to somehow jump in the direction of movement? That seems silly because it would require everything to jump simultaneously, not to mention what are they pushing off from when jumping since in a vacuum an attempted jump would result in no real velocity.

Maybe the device causes a torque type thrust throughout the device where the particles all begin spinning in unison in direction of the thrust? High torque spin is the only non-propulsion type of thrust I have seen in physics. Maybe by having particles individually spinning at high rates has resulted in the cumulative thrust?

I love that there is yet to be a known cause, that always generates excitement!

zyxt9 said:

I'm wondering if the wavelength of the laser might yield a potential explanation, as well as the mirror, but I'm just guessing. Just envisioning the photons becoming a little scattered passing through the medium of the mirror, the result being energy dissipation in perpendicular directions to the thrust. As for the wavelength, it seems a shorter one might result in more thrust as each crest hits the target. Since shorter wavelength beams require more energy to produce, they similarly would seem to pass more energy onto the target.

Just pure guesses, feel free to invalidate as I'm more likely wrong than right about these. It seems unlikely these causes could account for the high difference in performance.

Click to expand...

Wavelength matters. A 1 watt blue laser is fewer photons per second than a red laser, but those photons are more energetic.

I'm breaking down and googling radiation pressure.
http://en.wikipedia.org/wiki/Radiation_pressure

P = 2*Ef*cos^2(alpha)/c

For perfect reflection, the pressure is 2*Ef/c, which is 6.67*10^-9*Ef. So 1 W of photons can yield 6.67*10^-9 N under perfect conditions. That's what they got at NIST. 530 W * 6.67E-9 = 3.5e-6N. So these reaction forces are 1,000 times too big to be explained by radiation pressure. It seems like there's no way around it. Some of the energy must be absorbed by the structure...but how? Spinning yields torques. Photons can carry angular momentum. I don't know if there's a possible answer there of not.

I'm more willing to accept an answer that includes quantum mechanics because I don't understand that stuff.