Everything posted by joigus
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The Official JOKES SECTION :)
I think I've seen one of those somewhere.
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Trying to make sense of the Fabric Of Space (The field that consists of the smallest particle-like phenomenon )
Just to add to the mountain of very sound objections. I'm curious: How do you explain muon decay as a property of chains of protons? What about mesons? What would Tesla have to say about that?
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The Official JOKES SECTION :)
Doesn't look like a very functional clock, does it? But still, when in Rome do as the Romans do.
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The Official JOKES SECTION :)
To think how many dogs have had to put up with this shit... Last joke for today...
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The Official JOKES SECTION :)
- Reality Paradox
Nice account, by a top man in the field.- Correspondence between mass/radius of both the observable universe and black holes
Good point. I think before the universe was vacuum-dominated, the calculation with just energy density of matter and radiation works quite well, and you can actually do the calculation by Newton's gravitation, the result giving coincidence between Schwarzschild's radius and radius of observable universe. I suppose you could do the trick of including an additional term to the total content of the energy by adding vacuum energy, then you would have to recalculate Schwarzschild's radius and everything would check again.- Two brains with the same consciousness frequency
I think this belongs in the Brain Teasers section.- Quantum energy teleportation
Erm... EM waves have no De Broglie wavelength. Their EM wavelength would not make much more than a few meters? There goes your teleportation. Tunneling is not teleportation. It's about things getting past classically forbidden energy barriers. And it has attenuation: the probability amplitude at the other side is much weaker than in the classically allowed region.- Black Holes Do Not Exist!
Black holes do not exist. This must be a peanut:- Examples of Awesome, Unexpected Beauty in Nature
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 energy teleportation
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- Quantum energy teleportation
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.- Quantum energy teleportation
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.- Do virtual particles exist?
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.- Do STEM professionals despise nerds, geeks, introverts, and eccentrics?
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.- Homework help regarding force, weight , acceleration and momentum
Good members of the community helping along until everything makes sense and OP helping clarify own question. Business as unusual. Thanks to everybody involved.- Want to know
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.- Do virtual particles exist?
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.- My sci fi art
- How much pressure do you need to make air go near lightspeed?
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.- Paleontologists Find One-Billion-Year-Old Multicellular Microfossils:
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.- Common everyday things that shouldn't been made
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.- What is the Opposite of Superposition?
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.- Billion-year-old fossil reveals missing link in the evolution of animals
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: - Reality Paradox
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