Touching on the second question, since the ship would never actually reach the speed of light, the trip would not seem instantaneous to the people on board. However, the trip would seem much shorter to the people on board than it would to external observers. The people on board the ship would experience length contraction in the direction of travel making their destination closer to themselves, while external observers would notice the people onboard the ship moving slowly, ie, experiencing time at a reduced rate. Either way, the effect is that the people on board perceive the trip to be much shorter (in terms of both distance and time) than an external observer watching their ship. In principle you can get the perceived length of the trip (both distance and time) to approach but not equal zero, though in practice this would involve killing everyone on board and destroying the ship (and maybe even the galaxy).
I agree with the other commenters that the people on board will experience a consistent acceleration of 9.81 m/s² in your described scenario. It might help, conceptually, to imagine an external observer watching someone on the ship jumping up and down at this near-light speed, taking into account the severe time dilation they’d be experiencing: The difference in perception comes because, from the external observer’s point of view, the person on the ship is moving in extreme slow motion.
This says most of earth’s nitrogen was present when earth formed. The nitrogen cycle eventually leads to atmospheric nitrogen which can be stripped by solar winds except earth has a magnetosphere that shields us. So planets with no or a weak induced magnetosphere lose nitrogen. Earth does not.
It’s all sorts of fish-related detritus. You can use your yucky fish water to water your plants and they will love you for it, fish pretty much poop finished compost. Like rabbits.
Any addiction can be broken (the mental part, at least). The real hard part is you have to truly WANT it. You can’t magically wish discipline into existence where there was none before.
That said, I can’t seem to get rid of mine, but I acknowledge that my underlying problem is a profound lack of willpower.
Nitrogen is usually in the form of N2 and is very stable. We don’t really do much with this form of nitrogen because chemistry is hard so with each breath it just hangs around. The oxygen on the other hand js readily absorbed and used, converting it into CO2. We have to remove the CO2 to prevent toxicity and add O2 to prevent suffocation.
Not necessarily. The two things aren’t related. You yourself burn way more calories in a year than you store in your body or use for growth. Respiration is not just about growing. It’s about using energy for cellular processes: immune system, transporting chemicals around the organism, replacing old cells.
An organism can grow at one rate and use energy (expelling CO2) for other functions at a different rate. They aren’t really related.
They are related, because the energy they use and the mass they grow both come from absorbed CO2.
In other words, every molecule of CO2 expelled by a tree was previously absorbed by the tree. Unlike humans, energy use by trees is carbon neutral. Which means trees cannot grow unless they absorb more CO2 than they expel.
I’m not sure, why you’re interpreting my comment as a general statement. I’m specifically talking about trees. While it’s theoretically possible that they get carbon from the ground and actually respire more into the air than they absorb, while also growing wood, that would be extremely surprising to me. Unless there’s data supporting it, I don’t see why we should entertain the thought…
That makes no sense. The human body is on average carbon neutral. You eat carbon and then you excrete it. Same as trees. Except you don’t continuously grow like a tree for potentially centuries.
Of course it is. No carbon was created. And unless you’re putting on weight, your mass stayed the same. Carbon in, carbon out. I’m not talking about CO2 neutral.
I’m not making up any shit wth? How dense are you? A tree is carbon negative because it sequesters carbon continuously. A human adult is not, it’s carbon neutral - when observed in isolation. The human system is carbon neutral. It doesn’t matter where the car on comes from. You expel the same amount as you injest. I think honestly you’re the one who doesn’t understand what carbon neutral really means.
Turning carbon in the environment into CO2 by oxidizing it is NOT carbon neutral! If that was the case, then every car, plane, and coal power plant would be “carbon neutral”. That’s very obviously not the case.
Being “carbon neutral” means that you, or the operations of your business or your national economy, emit the same amount of carbon dioxide into the atmosphere that you offset by some other means. (Source)
It’s ALL about CO2! For the love of god, go read some articles. You have no idea what you’re talking about.
The next time someone says that to you - point to a tree and explain that - that thing over there is largely comprised of carbon that has been extracted from the atmosphere by photosynthesis- so what are you talking about?
Yeah, it’s the simplest answer, and likely correct. But a more interesting question is why they got it wrong and what assumptions and misconceptions did they make to arrive at the wrong answer.
Particles are just a way of looking at excited quantum fields. The Higgs field is always everywhere, giving things mass.
Honestly, depending on interpretation of quantum mechanics, you don’t need to acknowledge particles exist at all. It could all be fields becoming ever more entangled and wrinkled.
Photons are also bosons, right? Why do we need all the huge energy particle smashing experiment at LHC, while we can get any energy photons everywhere? What’s the difference?
I’d start with making a surface plate using Whitworth’s 3 plate method.
Next, make a perfectly square block, pick two opposing faces of that block, that’s your unit of length. Use your surface plate to make more and measure things against it.
If you’re really smart you would have made that block out of some sort of homogeneous material like steel and made it a perfect cube, not just perfectly square. That’s going to be your prototype weight.
Temperature is the easy one, make a thermometer. Mark where the liquid is at based on two different repeatability phenomenons. Subdivide as desired. Someone will come up with a “better” way later.
Time is another easy one, just build a pendulum and start counting.
That sould get you through most of the neo-industrial revolution.
The rest of the base units will come later for now focus on building a lathe.
The “observation” doesn’t occur when a person sees the result, but rather when the electron or photon interacts with the device (in this case the wall). The wall is making the observation. In this situation “observation” doesn’t have the traditional meaning, but rather refers to an interaction event.
So the same average result will happen no matter where the device is, the only thing that changes is its proximity to you.
Just like there are “islands” of relative stability predicted, there are also some islands of instability where the geometry just won’t line up correctly no matter how you arrange it. Think of an atomic nucleus like a soccer ball – A soccer ball has a specific number of pentagons and hexagons that fit together (almost) perfectly. You can’t make any such shape with hexagons alone. If you have even one too many or one too few, it might still make a mostly spherical shape, but no matter what you do it will have a weird wrinkle, flap, or gap somewhere, and that’s the kind of thing that will cause instability, it won’t balance correctly, it won’t fly true, and if the flaw is big enough eventually the inconsistency will tear it apart.
The patterns of various numbers of two dimensional shapes that can form a seamless sphere is not intuitive or obvious at a glance and the math required to compute it is reasonably complex, but the result is straightforward. Some combinations of shapes work easily for this. Others only work in very specific arrangements. And some simply won’t work at all. The same sort of idea seems to apply to atoms, although we can’t say we completely understand all the nuances of the forces at play, the principles and outcomes are easy to measure. This is of course still an area of significant research and study, because it is important and has implications and potentially applications ranging from deeply obscure astrophysics and cosmology questions to very potent energy technologies that could change our society. But no matter what we discover, our observations of the outcomes are quite consistent and very repeatable, and the atomic patterns that we call Technetium simply don’t stay together very long.
Lots of stuff about patterns that tile or do not tile into regular shapes does not make much intuitive sense, just like prime numbers and irrational numbers do not follow any obvious pattern we can predict, and indeed modern cryptography is dependent on the fact that prime numbers do not follow any particular pattern. Patterns that look like they should be trivial to fit together do not, like intuition might suggest that the square root of 2 should be at least a rational number if not a natural one. And things that look impossible to tile can snap together seamlessly when placed with some careful attention and planning. Technetium is like one of those mathematical or geometrical patterns that looks like it should be trivial but no matter what you do the pieces just will not fit together into any useful shape. At least not for very long.
Some further reading on patterns like Aperiodic Tiling might also be of interest. Lots of fun stuff down such rabbit holes.
I kind of feel the opposite. There are literally invisible spores that float around the air that can spring to life in the right conditions. Until you discover the means of transport, spontaneous generation is a hypothesis that matches the facts.
There are a lot of good answers here already, but I’ll try to attack the question from a new angle.
Firstly, yes: they experience an attractive force from the nucleus, and would in principle have their lowest possible potential energy if they were located exactly in the nucleus. An equilibrium state is the state with lowest energy, so why aren’t they exactly in the nucleus?
Consider that an electrons position and speed cannot be exactly defined at the same time (uncertainty principle). So an electron with an exact position could have any speed. If you compute the expectation value of a particles kinetic energy, when the particle can have any speed, you’ll find that it’s divergent (goes to infinity).
So: Because an electron with an exactly defined position must have infinite kinetic energy, the equilibrium state cannot be an electron with an exactly defined position, and so cannot be an electron exactly in the nucleus. So what do we do?
We have to make the electrons position “diffuse”. Of course, that means it is no longer exactly inside the nucleus, so it gains some potential energy, but on the other hand it can move more slowly and has lower kinetic energy.
The equilibrium state is the state we find where the trade off between kinetic and potential energy gives us the lowest total energy, which is described as a 1s orbital. The electron is “diffuse” enough to have a relatively low kinetic energy, and “localised” enough to have a relatively low potential energy, giving as low total energy as possible.
Once you start adding more electrons you need to start taking Pauli exclusion into account, so I won’t go there, but the same manner of thinking still essentially holds up.
Yes, there are an infinite number of velocities you can use, but if you look at their distribution, you’ll find that it quickly goes to zero somewhere around 1-2 m/s, so the expectation value of the velocity is convergent.
If you have an object with a velocity taken from a distribution that doesn’t approach zero sufficiently fast as the velocity goes to infinity, the expectation value diverges. A simple example would be a person that would be half as likely to get up at a velocity of 2 m/s as 1 m/s, and half as likely to get up at 4 m/s as 2 m/s, etc.
The more mathematical version of the same argument is to compute the kinetic energy of a particle whose wavefunction is a delta pulse (i.e. a particle whose position is exactly defined), and you’ll find that the particle has infinite energy.
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