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  1. Let’s look at this whole quantum entanglement business systematically, because I really don’t think it requires 22 pages of discussion and argument to understand this. It may be counter-intuitive, but it really isn’t that complicated. Suppose you have - to begin with - two completely separate particles, which aren’t part of a composite system; their states are thus entirely separate, and denoted by \[|A\rangle ,|B\rangle\] Don’t mind the precise meaning of this mathematical notation; it simply denotes two separate particles being in two separate states, where the outcome of measurements are probabilistic, and not in any way correlated at all. No mystery to this thus far. Now let’s take the next step - we combine the two particles into a composite system. The state function of that composite system is then the tensor product of the states of the individual particles, like so: \[ |\psi \rangle =|A \rangle \otimes |B \rangle \equiv |AB \rangle\] Again, don’t mind the precise definition of these mathematical operations; the idea here is simply that our two particles A and B form a composite system. Let’s, for simplicity’s sake, assume that each particle can only have two states, ‘0’ and ‘1’ - the physical meaning of the tensor product above is then that it combines each possible state of one particle with each possible state of the other, so the overall combined system can have four possible states: \[|00\rangle ,|01\rangle ,|10\rangle ,|11\rangle\] Thus the overall combined state of the particle pair is (I will omit the coefficients here, as the precise probabilities aren’t important): \[|\psi \rangle =|00\rangle +|01\rangle +|10\rangle +|11\rangle\] This is an example of a system that is not entangled - the combined state function can be separated into the individual states of the constituents, and all combinations are possible (though not necessarily with equal probability). Non-entangled states are separable into combinations of states of the individual constituent particles - they are tensor products of individual states - which means physically that there are no correlations between outcomes of measurements performed at the constituent particles. If you get state ‘0’ for a measurement on particle A, then you can get either state ‘0’ or state ‘1’ for a measurement on B, and these outcomes are statistically independent from each other. Mathematically, the tensor product makes no reference to the separation of the particles, ie it is not a function of their position, hence neither is the overall combined state. An entangled 2-particle state, on the other hand, looks like this: \[|\psi \rangle =\frac{1}{\sqrt{2}}\left(|01\rangle +|10\rangle \right)\] Notice three things: 1. Compared to the non-entangled state, two of the possible measurement outcomes are missing; the set of possible outcomes is reduced 2. The combined state cannot be uniquely separated into tensor products of individual states; it is non-separable 3. The form of the combined state does not depend on the spatial (or temporal) position of the particles - it is purely a stochastic statement, not a function of spacetime coordinates. What does this physically mean? Because the set of possible measurement outcomes in the overall state is reduced as compared to the unentangled case, there is now a statistical correlation between measurement outcomes - with emphasis being on the term statistical. There are now only two possible combinations, as opposed to four in the unentangled case. This is the defining characteristic of entanglement - it restricts the pool of possible combinations of measurement outcomes, because the overall state cannot be separated, due to there being extra correlations that weren’t present in the unentangled case. This is purely due to the form of the combined wave function - the outcome of individual measurements on each of the constituents is still purely stochastic, and not (!!!) a function of distant coordinates. Because the outcome (statistical probability) of local measurements is not a function of coordinates or any distant states, it is completely meaningless to say that this situation is somehow non-local, or requires any kind of interaction, be it FTL or otherwise. The entire situation is fully about statistics and correlations, which is not the same as a causal interaction; in fact, any interaction between the constituents (including FTL ones) would change the combined wave function and preclude the possibility of there being a statistical correlation while at the same time maintaining the stochastic nature of the outcomes of individual measurements. This is evident in the fact that the entanglement property of the above state function isn’t encoded in any kind of coordinate dependence, but rather in a reduction of terms, ie in a reduced pool of possible outcomes. This hasn’t got anything to do with locality at all, but is purely a statistical phenomenon. Hopefully the either helps, or possibly it might spark off another 22 pages of discussion
    4 points
  2. I think it is best to just keep the situation fully classic, and consider only physical clocks to begin with, rather than wave functions. The question of evolution operators in RQM is complex and very non-trivial, and does little to illuminate this underlying question. Time dilation is a relationship between reference frames, and not something that physically “happens” to a single clock. Asking for a mechanism that “slows down” some clock is thus meaningless - clocks always tick at the same rate within their own frames. So the correct question would be why inertial frames are related via hyperbolic rotations in spacetime - that’s a very valid question, but it isn’t one that any of our present theories can answer. So to make a long story short, we don’t have an explanation of why this happens, only a description of it. That’s not the same thing at all. The length of a world line between given events in Minkowski spacetime is defined to be equivalent to the proper time of a clock travelling between these events that traces out that world line. In other words, it’s simply the total elapsed time that’s physically measured on a clock that travels along a specific spatial path between events. Intuitiveness is not a necessary condition for a mathematical model to be valid and useful. It just needs to be internally self-consistent, and produce results that can be verified using the scientific method. I think you would agree that SR does this quite well. Beside, something being intuitive (or not) is a very subjective measure - many things I find intuitive might appear otherwise to you, and vice versa. I would, by and large, agree with you - though I wouldn’t put into such strong terms. I just think many depictions of physical concepts get the differences between what is an explanation and what is a description muddled up, especially within pop-sci publications. We do not yet know the underlying mechanism of why spacetime is what it is, but we do have an excellent description of its features. To fully understand why spacetime gives rise to the phenomenology we see, we’d have to figure out first how spacetime itself comes to be, and if it can be broken down further into more fundamental concepts. Such attempts are under way, but at present they are just ideas and conjectures. I disagree. Physics makes models of the world around us, but not all of these models purport to be a fundamental explanation in ontological terms. As such, SR is a very good model that is in excellent agreement with experiment and observation. It’s just important to not confuse a model with an (ontological) explanation, because they are not the same.
    4 points
  3. No, it doesn’t. What it does say is that you can decompose a Euclidean 3-volume into a finite number of subsets, each of which is itself a non-measurable collection of infinitely many points, and then reassemble these subsets in a new way. The crucial point here is that you cannot uniquely and self-consistently define the notion of ‘spatial volume’ for a non-measurable infinite collection of individual points, so this decomposition does not preserve the original volume, contrary to naive intuition. It’s a subtle ‘trick’ of sorts to do with Lebesgue and Banach measures. IOW, the Banach-Tarski paradox breaks down and reassembles a 3-volume in a way that does not itself preserve the original volume. Thus it is hardly surprising that you can turn a ball into two balls in this manner - in fact you could turn a ball into anything at all in this manner, no matter how big or small. It isn’t a true paradox, and most certainly not an inconsistency in mathematics. Also, don’t forget that unfortunately we do not really live in an infinitely sub-divisible 3-dimensional Euclidean world where such a procedure could in fact be implemented - it would be a neat little trick with lots of interesting applications!
    2 points
  4. Consider dG = dH - TdS For a column of atmosphere at uniform density & pressure under a gravitational field, a downwards vertical flow is favoured (supporting the argument of @studiot) since the release of gravitational energy increases total enthalpy sufficiently to counter the reduction in entropy due to reduced occupancy of the higher levels of the column. So we have established an equilibrium condition with a vertical density/pressure and entropy gradients much as the atmosphere we see around us. But for further gravitational settling of, say, CO2 to take place, the gravitational potential energy released is now countered not only by the entropy gradient, but also the necessary displacement of an equal volume of lower density gases previously below it generating an adverse temperature gradient and expansion of the lower levels due to both the temperature gradient and the reduced mass of the upper part of the column. In short, while dH is likely not zero for a perfectly uniform gas mixture (constant mole fractions) it becomes so small that it can support only a tiny mole fraction gradient. I therefore suspect that while @exchemist and @Ken Fabian are not quite 100% accurate in their assertions, in practical terms they are very close to measurable reality. It's certainly an approximation I used throughout my working career without a qualm. The 'phosgene' counter argument simply reflects the very low rate of diffusion of high molecular weight gases. The thermodynamic equilibrium remains an (approximately) evenly dispersed mixture. It's just that these cases take their time about reaching equilibrium.
    2 points
  5. @studiot my point was to clarify for readers that CO2 in mixed air doesn't separate and sink, even under those circumstances. We don't get stratification of the mixed air, we see stratification of pockets/volumes with different CO2 concentrations that have not mixed - yet. Sources will keep it that way but without them the enclosed air will - eventually - homogenize. Or I should say no significant stratification under ordinary Earth gravity; run it through powerful centrifuges and it can become significant. It is a common misunderstanding (whilst not claiming it of you) that CO2, being more dense, will sink to the bottom - and that the higher atmospheric CO2 concentrations nearer ground level are a result of the CO2 separating rather than the sources of CO2 being at ground level and there being a lag time in mixing. At small scale it mixes by diffusion. At larger scales by bulk air movements, ie wind and turbulence. For example thunderstorms will carry air from ground level to the stratosphere in one go, mixing vigorously as it goes.
    2 points
  6. The length of a world line between given events in Minkowski spacetime is defined to be equivalent to the proper time of a clock travelling between these events that traces out that world line. In other words, it’s simply the total elapsed time that’s physically measured on a clock that travels along a specific spatial path between event Excellent short answer +1 I would like to add to the second answer to the question "what does it mean....?" Minkowski imposes a cartesian coordinate system, which as Eddington pointed out a century ago, actually adds unneccessary mathematical structure. The same result could be achieved by a set of events and a set of the invariant intervals between them. This would form a network of linked events, with no cartesian structure superimposed. The sum of these invariants connecting any pair of events as a mathematical 'graph' (since this thread is partly about geometry, whch includes geometrical graph theory) then includes the shortest path. Ref Eddington The Mathematical Theory of Relativity pages 8 - 16, Cambridge 1923 (my ed 1954)
    2 points
  7. Reverse-image search produced this: https://www.cam.ac.uk/research/news/black-hole-powered-jets-fuel-star-formation It seems to be the result of a super-massive BH swallowing a region of star formation and producing as a result a pair of powerful jets of ejected material. The central bright region is probably the accretion disk of said BH. Not every spot of light is the BH. Black holes can't be seen directly. You can infer their position from gravitational lensing or from behaviour of matter around them.
    1 point
  8. First of all, what is "residual" herd immunity? Second, individuals don't develop 'herd' immunity. Herds develop herd immunity.
    1 point
  9. No. The vaccines for Covid do not have dead viruses, but regardless the answer is no.
    1 point
  10. I wouldn't characterize psychometrics as the staple of psychology; I would rather call it a branch. Psychology was not born as a science; it's more a convergence of medicine (as medicine grew and became more sophisticated and compartmentalized in the 20th century) and ministry (spiritual guidance, usually provided to a community by its shaman or religious guardian). People have always suffered from disturbances of the mind, but these were not always considered medical conditions. They are insubstantial - no boil to lance, no rotten tooth to yank; no fever, shooting pains or vomiting; no spots or rashes or lumps to examine. They manifest in ordinary behaviours in what is considered inappropriate situations - except what is considered appropriate and inappropriate varies by culture and situation. It manifests in moods and feelings that are normal in some situations, in some degree and duration, but are considered abnormal in excess - except that the assessment of excess is also cultural and situational. It manifests in distress felt only by the patient, but judged by other people, who cannot see, touch or feel it themselves. Consider the range of intelligence, sensitivity, temperament and resilience of human beings. Project that onto a big white wall. Superimpose the range of normal emotions, reactions and ideation of which beings are capable. Superimpose the range of philosophies and attitudes of societies to what is considered 'normal'. Superimpose the range of parenting style, influences, expectations and circumstances of childhood. Superimpose the list off the 'aberrant' behaviours people display. Superimpose the symptoms of exposure to chemicals in food, the environment, therapeutic and recreational substances. In front of that great big busy wall, put one young man who says: "Help me. I'm afraid to go to sleep." Where do you start? Trying to address that kind of dis-ease, to classify, codify, diagnose, trace to its cause and alleviate it is never going to be a slide-rule kind of problem.
    1 point
  11. And I explained that nobody was even saying this. So you were beating a dead horse. So let's try to explain it once again. As a starting point we take a Bell experiment, that closes the communication loophole. This means: the measurements cannot influence each other with a light signal, or any slower signal the decision which spin direction will be measured is taken after the particles left the entanglement source So there can't be any causal connection between measurement device A, B, and the entanglement source. Said otherwise, no communication is possible between these 3 components. To make the example as simple as possible we also assume that detectors and entanglement source do not move relative to each other, and the entanglement source is exactly in the middle, so the measurements are exactly at the same time in the rest frame of the experiment. Are you with me so far? Maybe Joigus' drawing helps: Just take Alice and Bob as other names for the detectors. So now we ask ourselves what Carla and Daniel will see. Well, it is in the drawing: in Carla's frame of reference the measurement at Bob's side is first, for Daniel's FoR it was Alice's side. It is just a question of perspective, not of changing anything with the experiment of course. Got that too? Now according SR observers can disagree on the timely order of events, when these events are space-like separated. But that is exactly what the closing of the communication loophole means. But SR also states that Carla and Daniel should at least agree on the physical process. But they don't: according to Carla, Bob's measurement determined the outcome of Alice's according to Daniel, Alice's measurement determined the outcome of Bob's But these cannot both be true. So the conclusion is that there is no 'determination relation' between the measurements. So no signal, FTL or not. For Alice and Bob of course nothing changes. In their FoR the measurements are simultaneous, just as before. So Carla or Daniel have no influence at all on the experiment. But they should agree at least on the physics.
    1 point
  12. I expect he means orthoclase, which is the softer of the two main minerals in granite.
    1 point
  13. What is the Mohs scale hardness of each of these? What is artaclase?
    1 point
  14. I don't know how long is a long time for you, but do you remember old fashioned steam railway engines or steam powered traction engines, steam rollers or other steam propelled equipment, or have you seen pictures of them ? They had one thing in common, they were big and very heavy. All that machinery to provide steam propulsion is very bulky and heavy. And yet their makers knew about thermondynamics and mechanics and made them about as efficient as it is possible to be. With various grades of liquid or liquified gas fuels it became possible to use different and far lighter mechanics for the propulsion drive. Now that is where the internal combustion propulsion is at today. A far ligher drive mechanics meaning a far lighter chassis meaning far more efficient use of the fuel. Furthermore it doesn't require to carry either a large and weighty tank of water or additional weighty mechanics to recover the water from the steam and recycle it. And don't forget that some heat is extracted in cold countries to heat the passenger cabin. So yes, it is possible but just not practicable, there are better ways to use the fuels. Note also the even more and smaller engines such as racing car engines wear out far more quickly than engines designed for road vehicles. It is somebodie's law that says the more efficient and highly tuned a car engine is the more servicing it needs and the shorter its service life.
    1 point
  15. There are additional replies better than I can give here: https://astronomy.stackexchange.com/questions/32445/head-on-collision-of-two-black-holes If energy is lost from a system (in its CoM frame), the system loses mass. The binary system is losing mass equivalent to the gravitational wave energy radiated away, before the collision. If an individual component of the system doesn't radiate energy itself, that component don't lose rest mass. Radiating gravitational waves can reduce angular momentum, so the remnant BH should be decreasing its angular momentum during merger and ringdown. After they're merged, the system only has the one object in it. Your question is basically asking about the components of the system before the merger, and the system as a whole after, that's the main difference. Also, I think the energy radiated while merging is vastly greater than that radiated during the inspiral phase.
    1 point
  16. OK I'll accept that it is not homework. I do not see any essential difference between looking up on Google and asking a real person so Granite has a Moh's hardness of 5.5 - 6.5 and decays by chenmical weathering to clay, which was (and still is) used to make bricks and tiles and of course Hammurabi's famous clay tablets for writing cuneiform on.
    1 point
  17. Non-locality means that the outcome of an experiment/measurement performed at a specific point (be that in spacetime, or in some abstract state space) depend explicitly on what happens at another point; so the outcome is not uniquely determined by physical conditions in a small local neighbourhood alone. Consider again the example of the entangled wave function I gave earlier. The respective observable here is the probability of finding one of the particles in a specific state. For example, the local probability of finding particle A in the state ‘1’ is exactly ½; simultaneously, the local probability of finding particle B in state ‘1’ is also exactly ½. The global probability of finding state ‘10’ is 1/2, and the global probability for ‘01’ is 1/2. Neither of these probabilities is a function of coordinates - distant or otherwise -, or indeed a function of the state of the other particle. At the same time, the probability of the overall composite state to be ‘00’ or ‘11’ is exactly zero - again, without this being a function of any coordinates. At no point is any of these probabilities a function of coordinates or distant states at all, so it is meaningless to speak of this situation as being non-local. It is, however, quite meaningful and natural to speak of the overall composite wave-function as being non-separable, which is purely a stochastic statement and has nothing to do with locality. It is also an example of the absence of local realism, which is a more general concept than locality. No, that is not at all what entanglement means. Please refer back to my previous post - entanglement means that the overall wave-function of the composite system has a reduced set of possible composite states as compared to the same system sans entanglement relationships. At no point does this make any reference whatsoever to the spatial separation between these particles. Again, entanglement is purely a stochastic phenomenon to do with the form of the overall wave function, it is entirely separate from any embedding of this situation into a particular spacetime. Note also that you can entangle more than just two particles at a time, again irrespective of how far the constituents of such an ensemble are from each other. Also no. Decoherence is a purely local phenomenon - it means that local degrees of freedom of a wave function become coupled with local degrees of freedom of its immediate environment, e.g. as a result of performing a measurement. Note that the global situation - i.e. the original system plus the environment it came into contact with - remains completely coherent, and thus global unitarity remains conserved in this process, as of course it must be. For example, if you perform a spin measurement on particle ‘A’ of our entangled pair, then its spin direction becomes coupled to the mechanism of the measurement apparatus. You now have a new statistical correlation - between particle A and the measurement apparatus which it comes into contact with it, as opposed to particle A with particle B. The exchange of information involved here is thus purely local, even if the entanglement between possibly distant particles is broken in the process. Two particles being entangled fundamentally precludes the possibility of them interacting in any way after the point when the correlation has first been established, irrespective of the nature of such an interaction (FTL or not). Interacting particles cannot be entangled, since the composite wave function of such a system cannot have the form quoted earlier while still maintaining local probabilities of ½ during the measurement of the entangled property.
    1 point
  18. If one thinks of the most widespread mineral material used by early man for building and for early artifacts, the rest can be confirmed fairly easily, using Moh hardness as a check.
    1 point
  19. I wonder, if it’s that diffuse, then how is it better than just putting the solar panels on the ground?
    1 point
  20. 'Weather' tends to keep the troposphere very well mixed as you suggest. Ozone is a rather strange fish on several counts. The long and short of it is that it has a short half life at normal sea level temperatures so it's natural distribution is generally limited to the frigid upper atmosphere where it's created.
    1 point
  21. I am sorry, this confusion has to do with little differences between languages on how to denominate certain scientific effects, situations or theories.
    1 point
  22. Expansionism to Soviet levels is Putin's MO. We either let him or we don't. The choice seems to be binary, given that, evidently, any opportunity towards a compromise just gives him time to remaneuver. This why Zelenskyy is not interested in talking to him at this point in the conflict It would be militarily and politically foolish to lose any hard earned gains to anything else, given that this conflict is going to be extremely difficult going forward in their winter, which apparently is brutal. Our next task will be helping the civilians and armed forces keep warm enough to endure the likely struggle ahead. Russian conscript losses are going to be an order of magnitude more numerous. The support they have in the field is pitiful. This image of a new influx of conscripts says it all:
    1 point
  23. A partial annex this year so we can have peace. In a couple of years V Putin tries again, and Ukraine lets him have another piece to keep the peace. Then a couple of years later ... ( there is no Ukraine left and V Putin moves on to the next country ) I wonder if he would have tried this stunt if Ukraine and the West had stood up to him in 2014 when he annexed Crimea ?
    1 point
  24. It helps those of us who wish to understand entanglement more clearly.
    1 point
  25. The receiver instantly knows if it is “0” or “1” but they can’t know what it means because even the sender can't know what they sent. In other words. You're saying that somehow, what you say is true, just because you say so, but nobody can ascertain experimentally, or even in principle, that it's true. Your simulation of an explanation is more or less the same in all your posts: You somehow know you're right, but you can't quite put your finger on why it's right, or even what exactly it is that you're right about. At this point I'm only just curious about your convictions from a purely psychological point of view. There's certainly no science to be learnt from anything you say here. And again, quantum particles have no identity: https://en.wikipedia.org/wiki/Identical_particles#:~:text=In quantum mechanics%2C identical particles,one another%2C even in principle.
    1 point
  26. Sorry; I just recall reading about entangling different color photons. If you can arrange it so that energy doesn’t identify the entangled property, or that the energy otherwise doesn’t matter, such as energy-time entanglement, which depends on the photons being created at the same time. “Each of the photons is directed into its own unbalanced Mach-Zehnder interferometer (see figure 3), giving it a long path (L)and a short path (S)to the detectors. Because the path length difference is much longer than the coherence length of the photons, no interference is observed in the single rates at either of the detectors when the phase in, say, one of the long paths is changed. However, there is interference in the coincidence rate between detectors. The reason is that there are two processes that could lead to such a coincidence count-both photons could have taken their respective long paths or both could have taken their respective short paths” http://research.physics.illinois.edu/QI/Photonics/papers/My Collection.Data/PDF/Hyper-Entangled States.pdf
    1 point
  27. Lake Nyos disaster is worth googling, on the dangers of CO2 accumulation on a large scale when there's a sudden belch of a lake. The cloud hugged the ground and moved down valleys, killing 1700+ people.
    1 point
  28. Same energy is not a requirement. Entangled photons can be different colors as long as the entangled parameter is not tied to one energy e.g. if vertical polarization has the higher energy, it won’t be entangled with a photon having horizontal polarization, since you can tell the photons apart.
    1 point
  29. To entangle two particles they have to have some (common) property that can only take two different values, but possess the same energy. In a bonding orbital you have two electrons that have this property since they must have opposite spins, due to the Pauli exclusion principle. Conservations laws, eg momentum may provide a pair of entangled particles in the right circumstances such as pair creation. But you can't just take any old pair of particles that happen to be close and say they are or will become entangled, for example adjacent electrons in the cathode ray stream impinging on your cathode ray tube are not entangled. Does this help ?
    1 point
  30. The answer is “yes” If you measure the particle states and they do not have the expected correlation, you know there had been a prior interaction. This is the idea behind quantum key encryption. If there was no prior interaction, you can infer that the state is undetermined. You can choose the correlation. e.g. photons with the same polarization state or orthogonal polarization states. You can’t choose the state of one particle, since the individual states are undetermined.
    1 point
  31. Yes, that’s precisely my point. It is meaningless to speak of length contraction and time dilation “happening” to rulers or clocks. It’s always a relationship between two rulers, or two clocks. No. That would be like saying that a topographical map of your local area relies on an “aether” just because it uses a coordinate grid. To be sure, you can make that claim without affecting the usefulness of the map itself, if you so wish, but it doesn’t add anything to the information contained therein. Spacetime is just the same - it’s quite simply a map of events that allows you to determine separations and angles. There is no implication that we need to reify this into some kind of physical substance. This guy disagrees: Yes! Very important observation +1 This very lucidly demonstrates why a specific choice of coordinate system cannot carry physical relevance, so far as the form of physical laws is concerned.
    1 point
  32. It's easy to say "keep fighting" when you're not the pawn being used in another's game of chess...
    1 point
  33. Durbin is right on with his urging Congress to pass a code of ethics for SCOTUS. Sorely needed. Leaks, failures to recuse themselves (this means you, Amy and Clarence), spousal influence and conflicts of interest... it's a cesspool atm.
    1 point
  34. ! Moderator Note The topic is SCOTUS leaks, not the details of the cases.
    1 point
  35. Sorry about the last couple posts; I went a little overboard. I'm an unreconstructed realist in the 19th-century mold, for whatever that's worth, so I find a lot of the modern ideas horrifying. But I can't disprove anything you've said, so I'll try to keep my mouth shut for a while. Thanks for chatting.
    1 point
  36. The madman is probably Aleksandr Dugin, whose book Foundations of Geopolitics had a powerful influence on Putin and Russian leadership generally. If you read a summary, it makes clear that US/NATO ceding any sovereign territory to Putin is a bad path to get on. https://en.wikipedia.org/wiki/Foundations_of_Geopolitics The book expresses an ideology called Neo-Eurasianism. The ideology of the Eurasianism was partially incorporated into a new Neo-Eurasianism movement after the 1991 fall of the Soviet Union. It considers Russia to be culturally closer to Asia than to Western Europe. This ideology was influenced by political theorist Aleksandr Dugin to publish in 1997 a magnum opus by the name of Foundations of Geopolitics. He later founded the Eurasia Party on the Russian political scene.[12] Political scientist Anton Shekhovtsov defines Dugin's version of Neo-Eurasianism as "a form of a fascist ideology centred on the idea of revolutionising the Russian society and building a totalitarian, Russia-dominated Eurasian Empire that would challenge and eventually defeat its eternal adversary represented by the United States and its Atlanticist allies, thus bringing about a new ‘golden age’ of global political and cultural illiberalism". In a sense. Though maybe sleepy indifference would be a better term than appeasement. I think maybe US and NATO lulled themselves into believing that giving Russia a seaport would pacify it and, hey, the Crimea peninsula was mostly ethnic Russians anyway so why fuss. Not sure if there was much awareness that Crimea was a domino falling.
    1 point
  37. They are the same, because rotation around a single bond is possible - unless there are specific steric hindrances from very large substituents, which a methyl group is not. Don't forget that the bonds in an sp3 hybridised C atom project in 3D, towards the corners of a tetrahedron. They don't stick out at 90 degrees in a plane, as shown in typical 2D representations like those in your example. If there were a double bond between C2 and C3 then rotation would not be possible and you could then speak of cis and trans isomers, depending on whether the substituents were on the same side or on opposite sides. In an sp2 hybridised C. atom, there are 3 bonds at 120degrees to each other in a plane, one or more of the bonds having some double bond character.
    1 point
  38. +1 You are moving into the territory that I meant when I said Every entanglement is different and depends partly upon the conditions of the entanglement. Ghideon's example is classical. But with the wife, socks, gloves and so on you need at least the information that they are married, there is a pair of socks of gloves. Otherwise when the box of gloves is opened the discovery that it contains a right hand glove is of no extra meaning. QM is no differnt in this respect, but obviously infomation required is different. For instance in the example Bangstom wants to avoid you know that two electrons in a hydrogen molecule are entangled, form Physics theory. But how do you move one away from the other without interacting (observing) with one or both and destroying the entanglement ?
    1 point
  39. You know what they say "if you build it, they will come." Have a nice game. What list? Don't touch the fire, because it hurts; define hurt and how would it's elimination benefit other's? Or, that other question, how can we use fire? That won't hurt anyone?
    1 point
  40. Future research will eliminate ten existing questions and introduce twenty new ones! 😁 😎 🙂
    1 point
  41. By all accounts it seems to have been Ukrainian AD system that went off course. The argument could be made for giving Ukraine mor emodern AD, like the Patriot or ( Israeli ) Iron Dome AD systems, so similar incidents are not repeated.
    1 point
  42. Yes, I mixed up KE and momentum. The kinetic energy of its parts contribute to the system's rest mass. In its center-of-momentum frame, the system has net zero momentum, and the total energy of the system is equivalent to its rest mass. This is galaxy PG1211+143 they're observing, about a billion light years away. Wouldn't they compensate for cosmological redshift? Wouldn't they describe the speed of stuff falling into a black hole relative to the black hole, and not the Earth?
    1 point
  43. Your punch velocity needs to be: 3725.95mph https://www.boredpanda.com/physics-major-calculates-how-hard-to-slap-chicken-to-cook-it/ Now, should you ever wish to cook a steak by dropping it from a great height (instead cooking a chicken by punching or slapping it), the required height depends on the level of doneness you prefer (rare, medium, well done). https://what-if.xkcd.com/28/
    1 point
  44. Put some Gallium to a Piece of Aluminium and watch after one week.
    1 point
  45. Perhaps antibody therapy for relevant cancers https://pubmed.ncbi.nlm.nih.gov/22437872/ and https://www.criver.com/eureka/magic-bullets-the-next-evolution-in-targeted-cancer-therapy and the term has meaning in the history of micrpbiology https://www.smithsonianmag.com/smart-news/syphilis-cure-magic-bullet-180964644/
    1 point
  46. While I would hesitate to call a nuclear weapon a precision instrument, there are treatments in medicine that you can describe as precise. Proton therapy, for example. You send a beam of protons at a tumor, and tune the energy so that the protons will deposit the bulk of their energy in the tumor rather than the healthy tissue, so you disrupt the tumor. (They have a proton therapy center at TRIUMF, where I did a postdoc)
    1 point
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