I suspect you may be misunderstanding time dilation. From the perspective of a particle, time always passes by at 1 second per second. If you yourself were to travel at relativistic speeds (relative to, say, Earth) your perspective of time wouldn't change at all. However, observers on Earth would see your "clock" to tick slower. That is, anything you do would progress more slowly from their perspective. In the very early Universe, a given particle would see most other particles moving at relativistic speeds, and so would see their "clocks" tick slower. These sorts of relativistic effects would influence interactions between particles during collisions, decay rates, etc, but are all things we know how to take into account in our models of the early Universe.
This is the first I've heard of the effect Mars has on Earth's Milankovitch cycles (unsurprising, given that the paper is recent and the effect is quite small with a very long period). Earth presumably has a similar effect on Mars, but measuring this would be quite difficult. Keep in mind that we're able to do this for Earth by analyzing drill cores (that paper uses data from 293 scientific deep-sea drill holes), which we can't really do for Mars currently. Using other methods, we've been able to measure the effects of axial tilt and precession for Mars, but the effect from orbital interactions with Earth would be much more subtle. I'd be surprised if you could find anything on it in the literature.
I also would not expect the Moon to make much of a difference. The Earth-Moon distance is <1% of the Mars-Earth distance even at closest approach, so the Earth-Moon system is essentially a point mass to first order. Additionally, the mass of the moon is ~1% that of the Earth, so the effect there is quite small as well. As I mentioned, measuring Earth-Mars Milankovitch cycles is already difficult for Earth (we apparently only recently did so) while likely infeasible for Mars (currently), and detecting the effects from the Moon would be harder still.
Assuming we're talking about refractive index here, metals technically still have a refractive index despite being reflective (light can penetrate a very short distance through metals). In the UV, the refractive index of mercury is <1 and of course it's very dense. But that's probably not going to be useful to you.
For transparent materials, water actually has a lower refractive index than most liquids (around 1.34 in the UV). You can check this website to see if there's anything better (probably an organic), but I doubt it would be by much.
I don't know much about 3D resin printing, but I assume you a focus an image (in the UV) onto a resin layer to selectively cure it. As you suggest, the presence of a liquid would refract the focusing light rays and change the position of the focal plane. This could in principle be accounted for by changing the distance from the focusing optic, though there could be some (perhaps minor) blurring of the image.
Yes, he's right that bringing the poles of two magnets together puts the system in a state of higher potential energy. And, yes, you could use this as an explanation for "why" the magnets repel by invoking the principle of minimum energy. You can even show that this results in a force, as a gradient in the potential energy is mathematically equivalent to a conservative force. I do think, though, that you can give further justification for the principle of minimum energy than he gives in the video, as it follows from the second law of thermodynamics (see Wikipedia article). Regarding the exchange of virtual photons and using this to explain how the electromagnetic force arises: I would avoid this entirely.
One side nitpick though: I wouldn't say that the energy came from "the chemical bonds in the food [you ate]", but rather the formation of new bonds as you digest the food. Chemical bonds are states of lower potential energy, so breaking them in the sense of separating the constituent atoms requires energy. It's just that different bonds can have even lower potential energy and therefore release energy when they're formed.
N2 is (mostly) inert when it comes to respiration. What your body needs is oxygen and low concentrations of anything that might also be metabolically active. For scuba diving, N2 is used to dilute the oxygen and is used specifically because of how non-reactive it is. At high concentrations though, it can result in nitrogen narcosis - helium is sometimes used as the diluent gas instead to mitigate this.
As far as habitability is concerned, atmospheric nitrogen is essential for life on Earth at least, as it's a major part of the nitrogen cycle (specifically, nitrogen fixation). Without it, we wouldn't have nitrogen-containing organic compounds like amino acids (and, therefore, proteins), at least not nearly in the same quantities that we currently do. This doesn't mean it's essential for life outside earth, but it is for life as we know it, so its presence should increase our credence (if only a little) for whether a given planet is habitable or not. However, when looking for signs of life, it's better to look for atmospheric signatures that are heavily influenced by life, rather than just those that facilitate it. The oxygen in Earth's atmosphere was largely produced by life, and so its presence in the atmospheres of other planets would be a good (though not definitive) indication of habitability.
I'm late to this, but I'd like to bring up something I haven't seen anyone else mention. But first, some more details regarding what has been discussed:
In most situations, it's correct to say that EM waves basically don't interact with one another. You can cross two laser beams, and they'll just continue on their way without caring that the other one was present. A mathematically equivalent scenario is waves on a string: the propagation of a wave isn't affected by the propagation of another, even when they overlap. Another way to put this is that they obey the principle of superposition: the total amplitude at any given point on the string is just the sum of the amplitudes of the individual waves at that point. You may want to argue that the waves do interact because there are interference effects, but interference is exactly what you get when they don't interact, i.e. when the principle of superposition holds.
However, this is only true for so-called linear systems. I won't go delve too deep into the math of what this means, but I think looking at the wave on a string example can give you some intuition. The behavior of waves on a string can be explained mathematically by treating the string as a large number of tiny points connected by springs. If the force on a given point by a neighboring spring is directly proportional (i.e. linear) to the spring displacement (Hooke's law), then you find that the entire system obeys the wave equation, which is a linear equation. This is the idealized model of a string, and the principle of superposition holds for it perfectly. If, however, the forces acting on points within the string have a non-linear dependence on displacement, then the equation describing the overall motion of the string will be non-linear and the principle of superposition will no longer hold perfectly. In such a case, two propagating waves could interact with one another as the properties of the wave medium (the "stretchiness" of the string) would be influenced by the presence of a wave. In other words, the stretchiness of the string would change depending on how much it's stretched (e.g. if a wave is propagating on it), and the stretchiness influences the propagation of waves.
Something analogous can happen with EM waves, and has been mentioned by others. In so-called non-linear media, the electromagnetic wave equation becomes non-linear and two beams of light (propagating EM waves) can influence one another through the medium. This makes sense when you consider that the optical properties of a material can be changed, even just temporarily*, when enough light is passed through it (for example, by influencing the state of the electrons in the material). It makes sense then that this modification to the optical properties of the material would influence the propagation of other waves through it. In the string example, this is analogous to the string itself being modified by the presence of a wave (even just temporarily) and thereby influencing the propagation of other waves. Such effects require sufficiently large wave amplitudes to be noticeable, i.e. the intensity of the light needs to be high enough to appreciably modify the medium.
What about the case of light propagating in a vacuum? If the vacuum itself is the medium, surely it can't be altered and no non-linear effects could arise, right? In classical electromagnetism (Maxwell's equations), this is true. But within quantum electrodynamics (QED), it is possible for the vacuum itself to become non-linear when the strength of the electromagnetic field is great enough. This is known as the Schwinger limit, and reaching it requires extremely high field strengths, orders of magnitude higher than what we can currently achieve with any laser.
*I want to emphasize that we're not necessarily talking about permanent changes to the medium. In the case of waves on a string for example, the string doesn't need to be stretched to the point of permanent deformation; non-permanent changes to its stretchiness are sufficient.
They do lol
Putting aside the issue that it requires a negative energy density, there's still the issue that it will necessarily violate causality, which is the reason FTL travel is considered problematic in the first place. Maybe it's ultimately okay, but it may also mean that warp drives are fundamentally impossible.
Heat can transfer through conduction (basically thermal diffusion through physical contact), convection (bulk motion of matter, like gas or water flow), and radiation. For a spacecraft in low Earth orbit, the pressure is considered ultra-high vacuum, so you basically only have radiation to dissipate heat. Near room temperature, this would be mid-infrared light. The energy in everyday sound waves is very small, so body heat, on-board instruments, sunlight, and perhaps even IR emission from the Earth would be much more important contributors to heat build-up. However, regardless of the heat sources involved, there will always be some equilibrium temperature where the energy going into the system equals the energy radiating away.
To keep things comfortable for the crew on the ISS, there are passive and active systems to regulate the temperature [1]. For dissipating excess heat, large radiators are used. These are basically panels with a large surface area in order to maximize emission of thermal radiation. A closed-loop system is used to circulate fluid, which collects and transfers heat to these radiators. Water is used for some parts, but others have pipes on the outside that use ammonia to prevent freezing. The radiators themselves can be retracted or deployed as needed.
[1] Memi, E. G. "Active Thermal Control System (ATCS) Overview." (2006): 19.
I feel like it's best to ease people into illusionism rather than hit them with a statement like "consciousness isn't real", which they will almost certainly misunderstand and reject if they aren't versed in the philosophy of mind (hence why it works well for this thread). As a teaser, I like the statement, "You are conscious, but not in the way you think you are", i.e. their consciousness is not phenomenal in character. What that means exactly is a lengthy discussion, but it gives an opportunity to emphasize the aspects of consciousness that actually matter and to potentially offset things like moral status over to them. For most people, morality hinges on phenomenality, so you have to replace it with something before they can accept illusionism (in my opinion).
Looks pretty good, but are you sure it's open source? I don't see the source linked anywhere on their website, and the "Description of Other Rights and Limitations" section of their terms of service suggests that it's proprietary.
Charge conservation would indeed be violated, which is why this decay is not expected. Dave is mistaken: the half-life they're referring to is an experimental lower-bound, not a actual expected value.