joigus

Where there's a will, there's a way. And even where there isn't exactly a will, there may still be a way.

Quantum tunneling is not free from attenuation. Look at this Wikipedia animation, for example: Also, quantum tunneling happens just next to the barrier, not far away. It's a completely different effect. https://en.wikipedia.org/wiki/Quantum_tunnelling

I was referring to the usual, i.e., speaking over the phone. Correlations at a distance are not magical, or anything new. But these correlations have to travel from Alice to Bob. Quantum correlations in entangled states are of a different nature. First of all, and most important, the word that Alice sets in her system is random. It's not like she can decide to send the word "ALERT" to Bob. That would be a code in binary 0100101101... etc. that she chooses. But she can't do that. All she can do is pick a spin projection --that much she can choose-- and see what word her system produces, which sometimes will be 0101001101..., other times 1101001000..., etc. Then she knows that, provided Bob has his magnets oriented in the same direction, he will measure 1010110010..., 0010110111..., etc. (the "complementary" words). She gains knowledge about Bob's state automatically. But the salient state is random. And were Bob to measure a different projection of spin, their respective states would be as uncorrelated as if they had never been in contact. This is a bit like a system that scrambles random words, so that the other user has the key to unscramble the message --the key being the particular projection they're going to measure--, but the words being completely random sequences --non-messages. What the uses of this technology would be, I don't know. But it's not completely obvious to me how they would take advantage of this technology.

Correlations at a distance is not synonymous with "entanglement". We experience correlations at a distance every day. In quantum entanglement it is essential that there is an observable "number of particles" so that you can tag particle 1 and particle 2. The quantum state is an arrangement of 2-particle states that cannot be factored: \[ \left|12\right\rangle -\left|21\right\rangle \] You cannot do that with classical fields. Also, certain polarisation choices allow you to contradict classical logic. If A, B, and C are certain statements "the car is red", or "the pencil is upwards", or anything you can conceive classically, you always have: \[ P\left(A,\neg B\right)+P\left(B,\neg C\right)\geq P\left(A,\neg C\right) \] Read: Probability of statement A and not B plus probability of statement B and not C is greater or equal to probability of statement A and not C. This is just as long as you can write properties A, B, and C as having a certain unknown value at the same time. Something like this: Quantum mechanics contradicts this. There are certain observables that you can pick for which QM predicts: \[ P\left(A,\neg B\right)+P\left(B,\neg C\right)< P\left(A,\neg C\right) \] I know of no example of mechanical rods or any other classical system that can reproduce that. I also think the complex-number character of quantum amplitudes has a lot to do with this.

I would tend to develop the argument along these lines. When someone puts forward a theory, there is an honest attempt to explain what we see or measure (let's call that "real"). But then it never stops at that; there are all sorts of concepts that are logically necessary to make the theory consistent. Taking up on your analogy with the map and the territory; we could ask: Are Meridians and Parallels real? I don't think anybody would say they are. They're just part of the theoretical scaffolding. There are no lines there, really. In the case of (perturbative) quantum field theory, if you want to describe a particle going from A to B, you always need to include these corrections due to particle-antiparticle pairs (fermions) being produced and re-absorbed before the particle reaches B; or standalone bosons being emitted and re-absorbed. They may just be a consequence of the way in which we partition the world with our theory. If some day people find a non-perturbative formulation of QFT that's entirely consistent and general enough, it may be the case that we can get rid of the concept of virtual particles entirely, and then we see them as just a contingency of the model of perturbative quantum field theory. The whole rationale of perturbative QFT is that I write down a dynamics that I can solve exactly, and then add smaller and smaller corrections based on calculational convenience. Why should Nature care about what we find easier or more difficult to compute? So maybe virtual particles are a consequence of our theoretical mapping, if I have understood you correctly.

I hate to corral people into these categories. You miss so much detail of the human landscape. @swansont with license to kill. I can see how that image has been burnt in your memory.

That's nothing. The iron in your blood carrying oxygen to your brain, so you can type, was born before the Sun was born.

Good members of the community helping along until everything makes sense and OP helping clarify own question. Business as unusual. Thanks to everybody involved.

https://en.wikipedia.org/wiki/Zeno_of_Elea https://en.wikipedia.org/wiki/Archimedes It's OK to confuse two guys who've been dead for more that 2000 years. I love the title of your thread "Want to know". I'm there.

No. And yes. They are very contingent concepts. As... perhaps most other concepts? "Exist" is not a good verb for describing reality, in the last analysis: Does the upper part of an electron exist? Does that look in my sweetheart's eyes exist? Does a name that hasn't been pronounced exist? Virtual particles are effectual, I would say. They don't exist, but they appear in calculations. If you measure their presence, then they "exist", but they no longer are virtual. That's the kind of circle we're in. And I don't know whether that's a satisfactory explanation, but that like the best I can do.

Very nice work.

You can do this by dimensional analysis. If the air is made up of just nitrogen, \[\left[P\right]=ML^{-1}T^{-2}\] (units of pressure) And your fundamental constants are the mass of the nitrogen molecule, \( \hbar \) and \( c \) (the speed of light.) \[ \left[\hbar\right]=ML^{2}T^{-1} \] \[ \left[m_{N_{2}}\right]=M \] \[ \left[c\right]=LT^{-1} \] Your pressure must be, \[ P=\left(m_{N_{2}}\right)^{j}\hbar^{k}c^{l} \] Gathering all together, \[ M^{j}\left(ML^{2}T^{-1}\right)^{k}\left(LT^{-1}\right)^{l}=M^{j}M^{k}L^{2k}T^{-k}L^{l}T^{-l}=M^{j+k}L^{2k+l}T^{-k-l}=ML^{-1}T^{-2} \] So the power equations are, \[ j+k=1 \] \[ 2k+l=-1 \] \[ -k-l=-2 \] whose solutions are, \[ k=-3 \] \[ l=5 \] \[ j=4 \] So your pressure would be the order of, \[ P=\frac{\left(m_{N_{2}}\right)^{4}c^{5}}{\hbar^{3}}\simeq2.5\times10^{51}\:\textrm{Pa}\simeq2.5\times10^{45}\:\textrm{atm} \] That's like \( 10^{29} \) times the density at the centre of the Sun. I think you're gonna make a black hole. Don't do it at home! Even though this is just dimensional analysis, if you take \( m_{\textrm{air}}=.7m_{N_{2}}+.2m_{O_{2}}+.1m_{H_{2}} \), you get a better approximation for the average mass of the air molecules.

No offence on my part. My thread got trolled soon enough. I wonder if protists are this wonderfully complex meta-kingdom where multicellular life arose. A powerful platform for evolutionary experimentation, so to speak. I know that kelp are the only surviving protists that are multi-cellular. If you take a look at protists, there are amazingly varied solutions to the basic problem of how to survive and pass on your genes.

It's another case of the law of unintended consequences. I'm sure the people who invented the plastic bottle never thought it was gonna grow to the scale it has. That's why I think we must change technologies from time to time. My rule of thumb is: Never do the same thing for 200'000 years. Neanderthals could afford it. We can't.

That one's easy. The opposite of Spain is Switzerland! I'm with @MigL on this one too. I would think that the opposite of having superposition is not having superposition.

What you, or I, or @Area54, or any other, "personally believe" has no bearing on what science is about. Science is concerned with evidence and finding a theoretical framework of ideas to explain that evidence. Besides, this thread is not about human evolution. Try your notions here, and see how they fare:

No, it was my bad syntax to blame, sorry. What I meant was: I, as you, am not sure that another nail in the coffin will do much to convince die-hard creationists. You expressed yourself perfectly. It was I who messed up my own meaning. Having said that, my main excitement from this kind of news is quite a different one, as I assume yours is, really. My main motivation is to have as many snapshots of these first faltering steps of life, as well as the levels of complexity that went with it. I know palaeontologists call this Archean period "the boring Billion", which is easy to understand why. But I think it's the opposite. Nothing could be more exciting than figuring out how a pot of chemicals gives rise to self-organising, self-replicating structures.

Somehow, I can't picture Bicellum brasieri making stone tools or grooming its buddies.

Thanks for the tip. I'm especially interested in the pre-Cambrian. Obviously the key to life is there. I'm not sure, as you, because of the word "unnecessary", that another nail in the coffin will do much to convince creationists. As someone very far from an expert, I would very much like to have a map of the territory, so to speak, of those Archaean seas, lakes, and puddles, and the events that took place.

Another piece of the puzzle of life. Seems to present very primitive form of cell differentiation, with only two types of cells. A billion year old fossil, which provides a new link in the evolution of animals, has been discovered in Torridon, Scotland. https://phys.org/news/2021-04-billion-year-old-fossil-reveals-link-evolution.html The organism was spherical in shape, suggesting also that cellular differentiation, "tissue" formation, and body plan were very primitive. https://www.cell.com/current-biology/fulltext/S0960-9822(21)00424-3

I tend to agree with @Prometheus. I find it difficult to see the paradox because there are so many unknowns. Let me give you an example: In recent years it's been discovered that there are microorganisms living underground and in the marine bottoms with life cycles completely disparate from those imposed by the Sun. This suggests that we are barely starting to understand the limits of life in our own planet. I would add the ethological argument. Namely: Why would another civilisation want to be seen by us? Predation, parasitism, territoriality, and other similar patterns in which one organism takes advantage of another are very common in Nature. Not always or necessarily to the advantage of one, the other, or both. Then there is the issue itself of how Fermi conceived of the question. It was a very informal argument arising from a conversation, that he later tried to make into a scientific argument, but I don't think he ever made it very rigorous or attempted to do so. Then came Drake and his equation. That's a more serious attempt at setting up the question. But still, so many unknowns... And going back to the original argument from Fermi, it sounds suspiciously similar to an argument from silence: We don't see any evidence of this, thereby it never happened. The way in which this kind of argument can mislead you has been extensively analysed in classical studies, archaeology, and all sciences that have to do with studying the past.

https://thelanguagenerds.com/

Uh, uh. Somebody didn't like your text formatting.

Only Aldrin left from the crew. Really an amazing guy. All these years passed have only made the feat look more and more impressive, not less. May he rest in peace.

Very subtle, and I'm not sure to what extent consequential. See, e.g., https://physics.stackexchange.com/questions/334478/mathematical-definition-of-classical-entanglement (My emphasis.) This, of course, can only mean that in those cases classical fields can be used as a workable approximation. Classical field theory cannot give you any phenomenology that's not already contained in quantum field theory, as QFT is the fundamental theory as we know it.