joigus

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.

There is no such a thing. I had a series of conversations with a friend who was refereeing for PRL on submitted papers that were using such a misnomer. It was decided that it had nothing to do with entanglement, and all the effects could be understood with the superposition principle. Classical field theory doesn't deal with photons (as particles), so there can be no entanglement from the point of view of classical fields. It doesn't even start to make sense.

Not all radiation is harmful. Long wavelengths are much less harmful than short ones. Yes, that's true. But that's why we have antennas. They exploit interference. No. Not all matter is a good absorber of radiation. Some matter reflects radiation, other matter diffracts it or transmits it. Most interstellar space is quite transparent to radiation. Air scatters radiation, rather than absorb it, for the most part. The point is quantum teleportation has particular features that are in no way like "sending something from A to B instantly".

Long-distance energy transfer is possible. It's called radiation. It's constrained to transfer speeds equal to the speed of light in vacuum, at most. I don't see how entanglement could achieve anything better than c-propagation for energy. As to claims that quantum entanglements play a part in photosynthesis, I wouldn't be terribly surprised if that happened. There have been claims that quantum entanglement participates in birds finding their bearings in long migrations. There are many claims of that sort. I would tend to be cautions about those claims, but it's possible. My sceptic half says that entanglement, in the usual meaning, is normally associated with cold, non thermal, conditions. But here's what I've found: https://mappingignorance.org/2020/05/21/high-temperatures-and-strong-random-interactions-need-not-destroy-many-body-quantum-entanglement/ https://www.nature.com/articles/s41467-020-15899-1 I would think that there must be a conceptual bridge between claims of entanglement playing a part in biological systems and study of entanglement in strongly interacting systems. But I would have to read this material more carefully. In the meantime, I'd be very interested in what other users have to say.

If Watson isn't the most famous doctor ever, then Who is. ------------------------- Meanwhile in Salzburg...

The nature of so-called "quantum teleportation" is very widely, very deeply misunderstood. Nothing is travelling "instantly", so nothing is teleported. Energy, of course, cannot be teleported either. What these experiments do is build highly correlated pairs of particles, and keep quantum coherence for incredibly long distances. They can then "switch off" coherence, so to speak, and can select sub-states completely correlated to each other. That's very impressive in and of itself, but no teleportation AFAIK. I wouldn't call this "teleportation", and I don't know who introduced that term, but it's a misnomer and it causes confusion to no end. I for one would prefer that scientists used a more understated vocabulary. But it seems to be the case that the more sci-fi it sounds the more hype it's going to stir. I think that's unfortunate. No, Star Trek is not around the corner. I wish it would.

LOL

"Imaginary" is just a word. Don't read too much into it. "Real" is just a word, don't read too much into it. "Exist" is just a word..., and so on. If a circle really exists, then complex numbers really exist. If a circle doesn't really exist, then complex numbers don't really exist. Can things kind of exist to you, instead of really exist? "Use" is a far nobler verb than "exist." You can use complex numbers and understand many things with them as a tool.

I wish I were in Tonga now. I'm waiting for the mods to say "nothing to see here, go to Tonga."