You were on to the right track; you just want to think about it in terms of what's happening at an atomic level. To get as close as possible to the actual physical diameter of a hydrogen atom, you'd want to imagine a situation where the hydrogen atoms were all physically in contact with each other. This doesn't happen in a gas, but it does happen (more or less) in a liquid.

The density of liquid hydrogen is going to vary based on external pressure, but let's start with sea level pressure just to give ourselves a benchmark. The density of liquid hydrogen is 70.85 g/L. I don't even bother doing the calculation with Avogadro's number here; I just asked Google "70.85 g/L = ? amu/nm^3" and it converted grams to atomic mass units and it converted liters to cubic nanometers just fine. The result? The density of liquid hydrogen is 42.67 amu/nm^2. We know that a single hydrogen molecule has a mass of 2 amu, so this suggests that a single hydrogen molecule in a liquid occupies a space of 0.047 cubic nanometers. Solving gives us a radius of 0.26 nanometers. So we can say confidently that a single diatomic hydrogen molecule MUST be small enough to fit within a sphere that has a diameter of 0.52 nanometers.

So how small does that make a single hydrogen atom? Well, you can look up the bond length of diatomic hydrogen and find that it is 74 picometers, or 0.074 nanometers. Covalent bond length is the distance between bonded nuclei, given intersecting electron clouds. So the diameter of a single hydrogen atom must be less than 0.45 nanometers. We're now well within an order of magnitude of the actual size.

Can we do better? Yes, we can, by looking once more at what's actually happening at an atomic level. Think about a ball pit: there's a lot of empty space between the actual individual balls. Being (essentially) spheres, hydrogen molecules don't pack into each other perfectly; they leave space in between each other. How tightly can you pack spheres together? This is a well-studied problem. In a perfectly hexagonal offset lattice, spheres can be packed with an average density (relative to the space between them) of π/3*2^0.5 or ~0.7405. That would be if the hydrogen molecules were arranged in a perfect crystalline structure. Unfortunately, hydrogen molecules are nonpolar so they don't have any intermolecular electromagnetic forces to align them that way; they will be packed randomly. This is called a random close pack and mathematicians have found that such irregular packings will produce a density of 0.64 or thereabouts.

What does this tell us? Well, if the density of liquid hydrogen is measured at 42.67 amu/nm^2, but the molecules are only packed to a volumetric density of 0.64, then 36% of that volume is going to be empty space. So the actual density of an individual hydrogen molecule is 66.7 amu/nm^2 or 0.03 cubic nanometers per molecule. This gives me a radius of 0.193 nanometers. Subtract the bond length and I get a diameter of 0.238 nanometers for a single hydrogen atom.

The actual size of an atom is known as the van der Waals radius. The van der Waals radius of a hydrogen atom is 1.09 angstroms or .109 nanometers. So the actual physical diameter of a hydrogen atom is 0.218 nanometers.

So our approach got us within 10% of the real number. Not bad!

You're right to do a sanity check; the size of a single atom of hydrogen is definitely not 3.7 cubic nanometers.

Your problem is that you used STP -- standard temperature and pressure -- above. At sea level pressures and temperatures, the gaseous hydrogen molecules (they're molecules, not individual atoms, but that's the least of our problems at this point) have so much kinetic energy that they are zipping around at hundreds of meters per second, constantly bouncing into one another. And so those constant collisions force them to spread out, until they occupy (on average) 3.7 cubic nanometers, even though they are physically infinitesimally smaller.

Any visible thermal glow is going to generally be limited to the engine nozzle itself. The primary visible aspect is reflected sunlight.

It’s drivable until you shift gears. And then it becomes very undriveable.

Well to be fair my tip (have a push start and keep the job in your pocket) is an anti-carjacking tip

There is no limit to how far you can see, if the object is bright enough.

Your eyes can see individual stars that are up to 16,000 lightyears away. You can also see the diffuse glow of the galactic core, which is around 25,000 lightyears away. And on a dark night you can even spot the glow of the Andromeda galaxy, which is 2,500,000 lightyears away.

A telescope doesn't change how far you can see; it changes how faint of an object you can see. An object that is twice as far away has to be four times as bright for you to be able to see it. An object that is 10 times as far away has to be 100 times as bright for you to be able to see it. Telescopes collect light from a large area and focus it into a smaller area, allowing you to see objects that would ordinarily be too dim.

So you’re quite correct on almost everything, except for the bit about being annihilated by Hawking radiation. This is the firewall problem. The event horizon cannot be defined objectively in general relativity; rather the event horizon is defined relative to an observer at a specified location. That’s because if the event horizon was a defined location, it would dictate a universal reference frame, which violates relativity.

So the event horizon cannot be accompanied by a firewall of deadly Hawking radiation. The currently accepted solution is that Hawking radiation is emitted from quantum fluctuations which are not only uncertain in energy but are also uncertain in location. And those fluctuations are redshifted or blueshifted relative to the observer, and so relativity is preserved.

It depends on the size of the black hole. For a supermassive black hole like Sagittarius A*, the average density is less than liquid water, and the tidal forces at the event horizon are negligible.

Yes, that’s the best solution we have. The information is encoded in quantum fluctuations in the shape of the event horizon, and Hawkins radiation is both caused by those fluctuations and carries that information away with it.

The universe could be trillions upon trillions of years old, such that we can never see the bulk of it because it is beyond our visual horizon.

However, if that was the case, then there would be nothing at the observable edge of the universe. It would just be darkness. But that's not what we see. When we look to the observable edge of the universe, we see a glow coming from every direction. That glow, despite being very dim and very redshifted, is our glimpse of the Last Scattering event when the plasma that birthed the universe finally broke apart into separate atoms and began to emit photons.

Since stars emit specific wavelength signatures, we can see how much those signatures have shifted to determine the amount of cosmic expansion that has happened between us and any given source. We see that objects farther away are more redshifted. The Last Scattering surface appears to be 40 billion lightyears away, and using the redshift we measure, we find that the light from Last Scattering must have been emitted 13.8 billion years ago.

I have a few friends in MPD and from what I've heard (only from them) it sucks, they loathe it, and it's really terrible. HOWEVER it's better than most other state/city-level LE agencies.

If you want to be in state-level or city-level law enforcement, it's a good gig. If you value your time and energy and emotional state, it isn't.

I will express no opinion on the OP, but I will observe that when I regularly rode the metro, I was stopped and harassed on numerous occasions by officers simply because my fare card didn’t always read properly. They’re capricious, drunk on power, and generally obnoxious.

There are a number of ways that a primary can capture a passing secondary. For a large secondary, one way that's fairly straightforward and easy to understand is ejection capture. Triton's orbit around Neptune is retrograde, making it unique among all the large moons in our solar system.

The most likely origin for Triton is that it started as a binary Kuiper belt object, like the Pluto-Charon system, but passed too close to Neptune. During the pass, the momentum of the orbit between Triton and its partner was added to the partner and subtracted from Triton, allowing Triton to be captured while its partner was ejected.

Hohmann Transfers are an important (and very interesting) topic but they're not relevant to ballistic capture, which is what the OP is asking about.

I can say that at my home in Brookland I have zero service with AT&T.

Glad to know it's not just AT&T.

Sucks that it's apparently everyone.