Recent content by timelessmidgen

Ok interesting, thanks! An example that the change in reflectivity might be very slight.

Thanks! Is it possible to estimate how rough the surface becomes or how much less reflective it would be than a polished surface? ETA: The underlying reason I'm curious about this is because I'm thinking about possible optical applications of phase change materials. Ultimately I'm curious about...

Would a small (of order 5 microns to 0.5 mm) liquid metal droplet, if cooled slowly away from external perturbations and not in the presence of oxygen, retain its highly smooth and polished surface as it froze? What phenomena would influence the surface roughness? I assume that simple density...

Great! I'm glad that my motivation for knowledge was deemed sufficiently worthy by berkeman to graciously allow this thread to continue. It is so upsetting when folks try to learn more for reasons that aren't deemed worthwhile. :oldeyes: To clarify, I'm well aware that a high vacuum is needed...

Thanks RPinPA! I prefer not to discuss many aspects of my world building while it's still in an unfinished state. Nonetheless, there is a plot element which requires far below light speed communication ( ~0.005c).

I haven't thought too much about those issues. To be clear, this is only a thought experiment, so you don't need to worry about my irradiating my neighbors ;) What are you referring to regarding high vacuum issues? The fact that at such high voltages I run the risk of frying any dielectric...

Haha, ok fine, no shocking pranks! Thanks, I'll take a look into those ideas.

The application is to accelerate particles (protons and heavier nuclei) to relatively high velocities (but not relativistic, maybe ~0.005c). A proton at 0.005c has kinetic energy of 12 keV, so 12 kV is of order the voltage needed. Please note that I'm not asking about the entire structure...

<< Mentor Note -- thread moved to the Sci-Fi writing forum after starting in the technical forums >> Hey folks, I'm interested in the feasibility of providing high DC voltages (~kV) in a physically small and low mass package (~grams). The power source does not actually need to be very energy...

Thanks marcusl, but what I'm asking is if they (the top left and lower right quadrants) can be derived not from each other, but from the lower left quadrant. IE, for a purely real signal is the full informational content of the DFT contained within the lower left quadrant? It's easy for me to...

Ah ok thanks, that's good to know. So in the case of a real signal do the top left and lower right quadrants contain additional information? Or are they derivable from the lower left quadrant?

When you do a discrete Fourier transform (DFT) of a one-dimensional signal, I understand that the second half of the result is the complex conjugate of the first half. If you threw out the second half of the result, you're not actually losing any data and you would be able to recreate the entire...

From a practical standpoint, can we combine two (or more) lasers tuned to almost-but-not-quite identical frequencies to create distance-specific illumination? For instance, say we have a 1 micron laser and a 0.9999 micron laser which we combine through some beam-combiner optics. In theory I...

Many thanks for the responses everyone! @berkeman: hmm, okay, it will take me a while to wrap my head around the circuit diagrams, but googling "diode frequency divider/multiplier" does indeed reveal the sort of thing I was wondering about!

Is it possible to design an unpowered antenna, (possibly some kind of RLC circuit) which will receive a radio wave at a particular frequency and then re-emit it at a lower frequency?