K^2

Because nobody cares about whether it generates a force. That's been well established by now. What people want to know is whether there is some obvious reaction force. And these are very difficult to exclude. In the setup in video, for example, magnetic interaction in power supply wiring cannot be trivially excluded, for example. Another common concern is air currents, which can also not be discounted here. List goes on.

Doesn't matter. Everyone is going to get their pulse at whatever delay they get it at, and that's the local time. And while the clock rate is going to be different in different parts of the galaxy due to the more distant areas getting older signal, the change is easily predicted. It might not be the most convenient time unit for actual day-to-day activities, but it gives us a simple way to synchronize clocks across the galaxy. What we actually decide to be the length of "one second", or whatever, is totally arbitrary, as you've pointed out. Computers will do actual time-keeping and conversions, anyhow. And pulsar pulse count can be the equivalent of the Epoch.

Pulsars. Enough said.

Apparently uniform distribution of visible stars has made people believe that we were at the center of the galaxy some time back. But no, we really just see stars in our immediate neighborhood. The galaxy just isn't big enough, in any direction, to bring in contribution from distant stars to the same level. It also isn't helping that there is a lot of dust between stars that absorbs light. Now, if uniform density of stars would extend further, interstellar gas/dust would heat up and glow as well. But, thankfully, our galaxy ends rather abruptly, and all of that interstellar stuff can cool down by radiating into intergalactic void. It's pretty straight forward to run the numbers. You should take average density of stars in Milky Way and an average luminosity of a single star and estimate how big the galaxy would have to be to get, say, 50% of Sun's brightness across the sky. You'll get a VERY big number. But our galaxy is tiny, so only the most proximate stars matter, and they are pretty uniformly distributed in our immediate neighborhood.

The argument is just the opposite. Universe is not uniform. That's well established. Nor does anyone expect it to be uniform. Nor does it need to be uniform to satisfy current expansion models. I have no idea where you're getting that nonsense from. They aren't. The only thing special about our location is that we happen to be at one of the density nodes. Because, you know, it's hard to have life discussing structure of the universe in the middle of an empty void.

Not at all. The whole point here is that we are always taking away. It's about fractals. For any uniform distribution in an infinite universe, no matter how far apart the stars are spread, and no matter how small they are in comparison, some finite fraction of the infinite space is occupied by stars. This is not generally so if macroscopic structure of the universe is a fractal. A fractal arrangement allows finite densities of the stars here, near us, but for the total density of stars in the universe to be precisely zero. Note, that number of stars and quantity of matter in the universe is still infinite. It's just that an overall average density is zero. A good, simple to understand example is the Serpinski triangle. We start with a large triangle, cut away 1/4 of it. Then cut away 1/4 of the remainder, and so on. What's the total area of all points that remain in the Serpinski triangle? Well, it's 1 - 1/4 - (3/4)(1/4) - (3/4)(3/4)(1/4) - ... I can re-arrange it to read 1 - (1/4) * sum((3/4)^n) for n = 0 to inf. That sum is easily evaluated as a geometric progression, and is exactly 4. (Wolfram Alpha). So the total area of Serpinski triangle is 1 - (1/4) * 4 = 0. Despite that, near any vertex, local density of points in the Serpinski triangle can be quite high. Our Sun happens to be near such a vertex. It's a star in a galaxy, which is in a group, which is in a cluster, which is in a supercluster. Of course, it's not a perfect fractal, but in a finite universe, it doesn't have to be. Nonetheless, if galactic densities of stars persisted throughout known universe, the sky would be pretty much as bright and hot as stars themselves are. It's all the empty space between galaxies, and between groups, and between clusters and so on that keeps the sky dark. It's all the stars that aren't there.

Even if it were just star distributions that were uniform, we'd have problems. There was a thread on why the sky is dark which partially addresses this. But it'd be problematic for stellar evolution as well. Sun is at least a second generation star. If it weren't, we wouldn't have life here. It's a weak argument that goes against a ton of data and would require changes to GR, which is one of the most precisely tested theories. You'll need way more than a curious arrangement of a few galaxies to even start suggesting that inflation doesn't work the way we think it does.

Strong base assumption gives pH higher than the answer. And if you look up literature values for pKa, it seems to indicate reason why. I've gotten pretty close to the answer with numbers from Wikipedia, but not close enough to be sure that they are the same values as given for the problem.

1) Structure of the universe is known not to be uniform. Uniform universe would be very bad news for us. 2) There isn't such a thing as "closer to the center". Every single point in the known universe was at the Big Bang, and is therefore, equally qualified to be the center. All of our data confirms that universe is inflating uniformly.

Possibly comes from the same type of events as Oh-My-God Particles.

More precisely, s is used for distance along the path, to distinguish it from d, which is displacement. The distinction is crucial once you go to 3D. The correct expression for work becomes W = ∫ F·ds = ∫ F·v dt

A steel needle with these parameters is 13m long, so it already pierces the styrofoam target to a depth of 8m from 5m away. Done. Always check your numbers for being sensible. Don't just make them up. If it's important that needle is 1g, estimate dimensions from that. If you want a very thin needle, with that kind of cross section, then compute mass from that. Next up, what exactly do you want to build? I assume you understand distinction between railgun and coilgun. There are still a whole bunch of different coilgun types. An induction coilgun, for example, is much better at firing rings than needles. It's also kind of easier to build, because it does not require switching the magnet off. That also makes all of the math easier. Though, you do have to understand a bit about how induction works. If you don't want induction, then material of the needle becomes critical. A coilgun won't launch a thin aluminum needle no matter how strong the field is. (Ok, not quite true, but you won't be able to get THESE kinds of mag fields at home.) So you need to make sure your needle is ferromagnetic. Furthermore, you'll need to have coil(s) switch on and off as the needles moves through. Pulling the needle in as it moves towards the center, but not pulling on the needle as it tries to leave. This is a bit problematic, because of the induction in coils themselves. The maximum velocity you'll be able to impart on the needle, and therefore, its penetration capacity, will depend in large part on how well the coils are switched on/off. And that will factor into all of this math in a non-trivial way. So I would strongly recommend to forego needles for a start and concentrate on accelerating a copper ring. It's a much simpler device with much simpler math.

First of all, "Having trouble with," and "Do my homework for me," are different in that you show us how far you've gotten with your own attempt. Then we can help you out. Second, there is a lot of missing data here. What other information are you given on C(OH)2? You might have something like pKb, solubility, etc. I'm getting slightly different number for pH, for example, and it might be just the matter of me using tables for different temperature. So you'll need to share whatever you're given on this substance.

More orange than red, even for the coldest ones. Hottest ones would be closer to yellow. If you want one that's actually red, you're probably looking for an L-class brown dwarf.

Not the amount, per se--it's the density. The phrase "critical mass" is misleading. As you increase the density of the plutonium core, the fission rate increases, and the temperature of the mass increases. And the thermocouples in the RTG produce more electricity. The problem being that, with a faster fission rate, the fuel source will decay faster.So there is one type of proposed RTG that exists only on paper to which your quote applies. Kilmeister's statement applies to every single RTG ever constructed. Are you sure this is the argument line you want to keep pushing?

It's the only isotop of Pu I'm aware of being used in RTGs. And since not being a neutron source is usually a selection criterion for RTGs, I doubt there are any that rely on neutron capture. If you know of any that do, I would appreciate a reference.

No, that's entirely false. 238Pu is not a source of neutrons. So density of fuel has absolutely no bearing on the reaction rate. 1g of fuel to 0.5W of power output. Regardless of shape. Regardless of density.

Fission is typically defined as nucleus becoming split into two or more nuclei. Alpha and proton emissions qualify. Neutron and betas do not. Though, it is not uncommon to use the word to exclude alphas. Hence presence of the qualifier "technically" in my previous post. In either case, the important question is whether neutron capture is relevant or not. There are spontaneous fission processes with heavy products as well. Likewise, there are alpha/beta decays that are triggered by neutron capture. The difference is specifically that RTGs tend to rely on spontaneous decay, while reactors and nukes rely on capture.

238Pu primary decay mode is alpha. Which is, technically, fission. But yeah, it's not about neutron capture, as it is with reactors or nukes. So you only care about total amount, not density.

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Moot point, since by now, the serial numbers have been confirmed to belong to the missing 777.

Griffiths' E&M is, indeed, really good. He also has a very good introductory text on Quantum Mechanics.

Course on Theoretical Physics is a series. The first one, Mechanics, is quite accessible if you know basic Calculus and just a bit about Differential Equations. It ramps up pretty fast from there, though.

You've misread. Wormhole is a topological feature. You either have one or you don't. You don't need any special conditions to have a stable, non-traversable wormhole. Likewise, there are known, unstable traversable wormhole configurations that do not require exotic matter. It's only if you want stable and traversable that there are no known configurations that do not require exotic matter. However, there is no general proof showing that exotic matter is a necessary condition even for these. Just conjectures based on known configurations.

And that's already a problem, since string theory has made a whole bunch of predictions that haven't panned out.* By the way, what you're looking for is called a traversable wormhole. No known stable traversable wormhole configurations are known that do not require exotic matter. * Although, pretty much any theory with more than 4D, be it branes, holography, or what have you, would have gravitational interactions that go beyond 4D as well. Problem is, we've found no indication of this on microscopic level, and it's very difficult to imagine a system where this would have macroscopic effect equivalent to dark matter without detectable microscopic consequences.