1. Harley (who told me today that she builds electrical circuits with her dad for fun): How can you make something (e.g. the wire polarizers) thinner than hair?
Hi Harley! Keep up with the electronics! It’s how the world works these days!
A brief diversion:
First computer program ever: Ada Lovelace
First compiler, that lets people write in human-readable code, which the compiler translates into electronics-readable code: Rear Admiral Grace Hopper. She coined the term “bug in the code” because she found a moth trapped in a relay that was making the code not work.
First interactive program ever: Margaret Hamilton, for landing on the moon. She wrote the Apollo program software, and invented interactivity, which she called “human in the loop”. She coined the term Software Engineer.
Lynn Conway worked out the rules for making integrated circuits work. She taught everyone on the planet how to make microchips. She’s a transgender woman.
So, if anyone tells you that coding is for boys, or that girls aren’t good at it, not only is that misogynistic drivel, it’s also showing that they don’t know anything about history. The vast majority of early computer programmers were women.
The wire we use for the wire grid polarizers is made of tungsten, which is very hard. It’s hot drawn through a tiny hole in a diamond, and then hot drawn through another, tinier hole in a different diamond, over and over until it is the size we want. It takes a lot of steps to go from a tungsten rod of about an inch in diameter down to wire that is 0.00014 inches in diameter. The wire is expensive because of that. It costs about $1 per foot of length. Each polarizer has $5000 worth of wire in it!
“Tungsten oxide can be roasted in a hydrogen atmosphere to create pure tungsten powder with water as a by-product.”
2. Ky (who helps his brother work on his car): Why do you use pi for the distance between the wires?
(2a) Jeromeel: Yes, why pi?
Hi Ky, Hi Jeromeel! Working on cars is great! It’s getting more difficult to do, because of all of the electronics. Maybe you two can work with Harley to learn some electronics!
What we want is to have exactly half the light pass through the polarizer and half the light bounce off the wires in the polarizer. The light with its electric field parallel to wires will make the electrons in the wires wiggle along the length of the wire, taking up the energy of the incoming light, changing it from electromagnetic (light) energy, to kinetic energy in the electrons. But wiggling electrons create a wiggling electric field, which changes their kinetic energy back into electromagnetic energy, which is light. That’s how all reflections of light work. Anything you see that isn’t glowing on its own power you see by its reflected light. Electrons are busy making things visible to you.
The incoming light that has its electric field wiggling perpendicular to the wires tries to make the electrons wiggle, but the electrons can’t move sideways far enough in the wire, and they can’t jump from one wire to the other at that sort of energy level, so the light doesn’t get absorbed and re-emitted, so it doesn’t get reflected. The light just goes right through as if the wires weren’t there. (From the light’s point of view, the wires aren’t there!).
If the wires are too far apart, then some of the light with its electromagnetic field parallel to the wires will pass through, because there aren’t enough electrons per area to absorb and reflect the incoming light power. If the wires are too close together, the electrons in adjacent wires can start to affect each other, which can start to reflect some power. Putting the wires at π times their diameter apart is the best spacing to reflect the parallel polarized light and transmit the perpendicular polarized light. I didn’t do the math for that, someone who specializes in thinking like light does did the math. Apparently it’s not that particular, something near π seems to work. But π is a convenient number to use, so we do. We tested the reflection and transmission of the two polarizations, and our polarizer worked so well that it was better than we could measure with our best instrument (a Microwave Network Analyzer).
3. Nicole: Why do you want to investigate the Big Bang?

Hi Nicole!

We are curious. We want to know why the Universe has matter distributed in it the way that it is, and not some other way. (Stars, Galaxies, Galaxy Clusters, and some pretty interesting structure on really really large distance scales.)
“How did these structures form? Most cosmologists believe that the galaxies that we observe today grew from the gravitational pull of small fluctuations in the nearly-uniform density of the early universe.”
So we want to look at the Big Bang to see if our idea of how structure formed is true, or not true. 

4. Everyone: What’s the Coriolis Effect?

Hi Everyone!

Suppose you are playing catch, tossing a ball back and forth. If one of you misses the catch, the ball goes past you and keeps going for a bit, in a straight line (with gravity pulling it down), until it hits something. So far so good.
But suppose you are playing catch in the car, throwing from the driver’s side to the passenger’s side. (Please don’t do this for real, driving is already dangerous enough without a loose ball in the car!) When one of you misses the catch, the ball goes flying out the window and keeps going. But if the car was moving, the ball was moving too, so the ball is not just going sideways out of the car. It’s also, from the point of view of someone standing and watching the car go by, moving in the same direction as the car. So the ball not only moves sideways, it also moves forwards.
So if you throw a ball from the equator of Earth towards the North or South pole, the ball keeps going, not only North or South, but also a bit to the East, because the parts of the Earth at the Equator go towards the East faster than the parts of the Earth farther from the Equator. (Spin a globe or ball to see this. The parts near the poles go around in a much smaller circle in the same amount of time (which is a lower speed) than the parts near the Equator, which have to go the whole diameter of the sphere in the same amount of time (higher speed).
5. Denzel: Why do certain subatomic particles just appear and disappear?

Hi Denzel!

Ha! Wouldn’t we like to know!!! We don’t know. It’s just what the universe is like. Really. Down at the scale of really small distances and really small masses, the Universe is a strange place (to us). “Anyone who is not shocked by quantum theory has not understood it.” — Niels Bohr
The mathematics of combining wavelengths is known a Fourier Transformation.

6. Jeromeel: How realistic is the science in Ant Man (e.g. the Quantum Realm)?

Hi Jeromeel!  I haven’t seen Ant Man, so I don’t know. Is it a good movie, fun to watch?

7. Ky: Do you watch The Fantastic Four (the one with Chris Evans as The Human Torch)? How realistic is it that they [the characters in The Fantastic Four?] got their powers by a solar flare?

Hi Ky! Not realistic. Fun, but not realistic.

8. Ky: Is it possible to run on water? What’s the science behind that (running something on water)?

Running an engine on water instead of gasoline?

Heh. This is pure crap. You can run an engine on hydrogen and oxygen, which, when burned, combine to make water and release heat by their combining. The heat is what you use to push the pistons to make the engine go. Can you burn water to get energy out? No. Water is pretty much as far downhill in terms of energy as you can get. Can you push it uphill in terms of energy? Sure, you can use electrical energy to split the hydrogen from the oxygen in water to make hydrogen and oxygen gas, which you can later burn to get the energy back out. Where did the energy come from? From the electricity, in this case. Where’d the electrical energy come from? Solar power (directly from sunlight to electricity), or wind power (from sunlight to moving air to spinning magnets to electricity), or hydropower (sunlight evaporates water, which rains at a high elevation, which flows downhill, which spins magnets to make electricity), or burning a fossil fuel (sunlight which made plants and bacteria which got fossilized into coal or oil or natural gas, which can be burned to make heat to make steam to spin magnets to make electricity), or nuclear power (which uses the heat released by nuclear fission to make steam to spin magnets to make electricity. None of those get their power from the water itself. So, no, absolutely not, you can’t run an engine using water as a fuel.
Or running on water like a Basilisk Lizard?