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  1. Just to clarify. The matter dominated era comes later; the first era was radiation dominated. What later became matter, with mass, was originally all massless radiation ( possessing the property of energy ), because the Electroweak force had not decoupled yet for the Higgs mechanism to give mass to Fermions, This would have been when the observable universe was in causal contact ( light/information has time to traverse it ) in order to establish an equilibrium that ensures isotropy and homogeneity, prior to a vacuum energy driven inflationary period that expanded that observable universe many many orders of magnitude. See Alan Guth, Electroweak symmetry break, and Inflationary Theory.
    2 points
  2. No matter was not "in the form of energy". That is the same confusion as before. There would have been radiation and fields (radiation is a form of oscillating field) that possessed energy. The entity is the radiation, or the field. Energy is one of its properties, along with other properties like direction, phase, frequency, amplitude and so forth. But my very limited understanding of this (I'm not even a physicist) is that when you try to extrapolate back you reach a limit at which our current theories of matter, radiation and fields etc break down. So we can't "see" any further back, even theoretically. Strictly, the big bang theory starts from the limit of credible extrapolation. All the stuff about singularities etc only has the status of conjecture, so far as I know.
    2 points
  3. There is a special happy feeling knowing one is not part of a garbage fire. Didn't walk from Springer Mtn to Mt Katahdin, but I walked some of it in Vermont and NH. It's all common sense stuff - pick your time (e.g. not winter in the north, not high summer in the South), bring a partner you don't mind having inspect you for tics, bring mosquito repellent, sturdy hiking boots, etc. Keep food in a bag and hang it from a high tree branch when you sleep, never in your tent. Take increasingly long walks before the trip, for several months, to build up muscles and spot any joint/tendon issues beforehand. Keep socks dry. Watch out for the protozoan fiend of Appalachia, Giardia lamblia. Do your homework on finding a high quality water filter that will strain out Giardia - pump filters are the best. Boiling water is a monumental PITA. Ditto cooking. Dried fruit, oat bars, pemmican, peanuts, trail mix, powdered milk or powdered non dairy drinks, are all handy sources that don't need fuel to prepare. Don't gather trail sources of food unless you know exactly what you're doing. Blackberries yes, mushrooms no. No sustained eye contact with bears. Etc.
    2 points
  4. I think if there were scientific evidence it would be documented better than in a youtube video (which, BTW, needs to comply with rule 2.7, found in the “guidelines” tab; a video is not a substitute for substantive discussion and documentation. Asking people to watch a 25-min video rather than you putting the effort in to explain the situation is not going to fly)
    2 points
  5. Merleau-Ponty construed existence as understood through the body. https://en.wikipedia.org/wiki/Maurice_Merleau-Ponty Merleau-Ponty understands perception to be an ongoing dialogue between one's lived body and the world which it perceives, in which perceivers passively and actively strive to express the perceived world in concert with others. He was the only major phenomenologist of the first half of the twentieth century to engage extensively with the sciences. It is through this engagement that his writings became influential in the project of naturalizing phenomenology, in which phenomenologists use the results of psychology and cognitive science. Merleau-Ponty emphasized the body as the primary site of knowing the world, a corrective to the long philosophical tradition of placing consciousness as the source of knowledge, and maintained that the perceiving body and its perceived world could not be disentangled from each other. The articulation of the primacy of embodiment (corporéité) led him away from phenomenology towards what he was to call "indirect ontology" or the ontology of "the flesh of the world"
    2 points
  6. But only for what you think is in the proposal. You don’t have those details (or haven’t shared them), so we don’t know - you’re just guessing. I’ve pointed out a few logical things that might have been in the proposal that you did not include. I’m not making any argument. I’m just pointing out the incompleteness of your assertion, and asking you fill in the gaps. Instead of doing so, or even engaging in exploration of it, you attack. It’s quite telling. It’s also quite obvious.
    2 points
  7. That's a good reason, thanks for the info...
    2 points
  8. As I recall, what I was reading in the studies of student performance was more related to students having to get up early than to negotiating transit in the dark. The problem is that children respond to sunrise and seem to do better cognitively when the light is well advanced and they have had maximum sleep while it was dark or pre-dawn. (the DST effect was especially bad if they were located at the western edge of a time zone, where the sunrise is last to reach) These studies also drew the conclusion that later school hours would be beneficial, even where there was no DST. The Circadian rhythmn actually shifts later during adolescence, so the need there is especially acute. Here's one digest of that research: https://www.apa.org/topics/children/school-start-times
    2 points
  9. This is one of those “why are things the way they are” that physics can't address, because we can only observe how things behave. Bare charges and their electric field come as a set.
    2 points
  10. To show off to the world what the US could do? Japan was already beaten. We also found out that the Nazis never developed anything close to an A bomb. Japan was already totally cut off from the world by US submarines and air force. No more imports so they were on the verge of starving. They were also having their cities systematically destroyed by huge B29 incendiary strikes, like the one that killed 100,000 people in Tokyo IN A DAY. All that happened by using the A bomb on Hiroshima and Nagasaki was to REVEAL to the world that such a weapon EXISTS. What they should have done, IMHO, is realize that nobody needs to know about IT, and that IT should be covered up so nobody else can create an A bomb. There should have been a HUGE, Manhattan-Project-sized, intelligence operation to do everything we can to make sure that no country can create such a bomb, except for the US. The US would TRY keep the A bomb a secret as long as possible. That would have saved so much money. Of course you can't keep something like that a secret forever, but at least stall it as long as possible. Or is this a naive proposal?
    1 point
  11. Analogy doesn't help much with this. It confuses things further. Very simply, so simply that it can't possibly be held to any degree of accuracy: the universe was extremely small, the matter in it was extremely dense and therefore extremely hot, and then the universe (which is everything there is) expanded rapidly (and the last point, working backwards, at which we can accurately measure it is what we call The Big Bang). At some point, the density of matter decreased enough to allow space between it to form, and the temperatures continued to fall. It could be that all that matter squeezed so small is similar to what happens in a black hole, but black holes happen inside the universe, and particles that fall inside are measured relative to the black hole, and no velocity can change that. When the whole universe is inflating itself so rapidly though, everything is different because everything is moving and expanding, everything in the universe is participating in the event. And I've probably made it worse.
    1 point
  12. Mining asteroids makes economic sense only if you leave the metals out there, for use in outer space endeavors. Imagine having tons of metal to work with that you didn't have to bring up from Earth's surface a few kilos at a time at hideous cost.
    1 point
  13. Strictly speaking, I mean the Weyl tensor, traceless Ricci tensor, and Ricci scalar. One can combine these in a multitude of ways, but these three are the true algebraically distinct curvature tensors.
    1 point
  14. Yup, that’s a (quite common) misconception. We can only speculate about what might have been first, but what’s for sure it wasn’t just “energy” somehow existing on its own. That would be as silly as claiming that what came first was “momentum”, without saying the momentum of what. You can’t have a jug of energy any more than you can a jug of momentum, or velocity. All these are properties, not entities. Incidentally, “m” in Einstein’s equation does not stand for matter, it stands for mass, which, like energy, is a property of matter, not a free-standing entity. Another misconception is that the equation predicts “conversion” between energy and mass. What it actually says is that rest mass has energy. It’s not one or the other but both at once. The entities involved are radiation and matter. Energy and mass are properties. In the early stages of the big bang model, there is thought to have been radiation, and sub-nuclear particles, I think. It will have been these entities that possessed the energy.
    1 point
  15. Thanks for your explanation. But what if the "surface" or skin of the balloon, had a thickness of over 100 billion light years? Then the expansion would resemble what we can see, no voids would be seen, and we would not know the direction of the expansion. Are you suggesting that the big bang was not an expansion of energy? First there is energy. Much later, after it cools down, a huge amount of energy congeals into a small amount of matter, E = mc2, so E/c2 = m.
    1 point
  16. Well temperature is proportional to energy so in a way it is just a matter of choice of units whether one talks about temperature or energy in this context. To my way of thinking the distinction between the role of modes is not real, since all degrees of freedom that are excited (at NTP in gases vibrational modes generally aren't) contribute 1/2kT each to the overall energy - which means temperature, in effect. Yes, pressure is proportional to the temperature (or energy) in the translational modes, but it is also proportional to that in the non-translational modes too, as they are all equal. One test of the idea that the translational modes are special might be if one could make a case that the flow of heat is transmitted only through translational motion. I am sceptical, since the modes all exchange energy.
    1 point
  17. That's not a level of knowledge, that's an age range. We're a science DISCUSSION forum. We talk about science topics. Videos are difficult to discuss, and take a fixed amount of time to view. We prefer the written word, where we can assess a post very quickly for veracity and accuracy. We can talk about subjects for your channel, but we have no interest in helping you promote your channel, which is usually what people want when posting their own videos here. We would love to talk about Earth Science with you. Watching you talk about Earth Science? Not so much.
    1 point
  18. This would be contributions from distant sources, as opposed to local ones, as well as contributions from any non-zero cosmological constant. Basically anything that stops spacetime from being completely flat before you account for any local energy-momentum. I agree, in this type of scenario you have clear causation in an operational sense. However, I was really thinking more of an isolated system where all parts remain in free fall at all times. Energy-momentum is locally conserved (the divergence of the tensor vanishes) - but then so is curvature (Einstein tensor). You cannot locally create nor destroy Einstein curvature, any more than you can create or destroy energy-momentum. You can only shift these around, and have them change form - so which ‘causes’ which? Not directly, but it contains energy density.
    1 point
  19. If light is not of sufficient strength, the plants will stretch towards the source causing weaker stem growth and greater spacing between leaf nodes, and affect synthesis resulting in some blanching. I suspect but say can't say definitively that longer 'days' won't alter that. Stronger light generally results in shorter, more dense and vibrant growth.
    1 point
  20. Curvature is a two-dimensional notion. It requires a surface to be curved in both directions. So, a sphere is curved but a cylinder is not. In higher dimensions, curvature can also be considered in terms of sectional planes. However, in two dimensions, there is only one type of curvature; in three dimensions, there are two types of curvature; and in four or more dimensions, there are three types of curvature.
    1 point
  21. Unclear to me what "any background geometry" would be here. As @Genady pointed out, causation can be defined operationally, e.g. I push two distant planets together and local curvature increases in "response" to greater local mass. The stress-energy tensor includes mass, right? Energy density is the whole thing in GR context - rest mass, pressure, momentum etc? I agree with @Moontanman on how interesting this thread is. I wish I had spent more time in my youth on physics instead of counting cougar scat.
    1 point
  22. While these comments are certainly true, I think the relationship isn’t as trivial as it might appear; after all, a vanishing Einstein tensor doesn’t necessarily imply a flat spacetime, so these equations form only a local constraint on geometry, but they don’t uniquely determine it. Any background geometry is as much considered to be a ‘source’ as is local energy-momentum, when it comes to working out the particular form of a metric at a certain event. Furthermore you have the non-linearities of the constraint itself, which, in some sense, might also be considered a ‘source’. But those contributions of course don’t explicitly appear. Personally, I just think of spacetime as pure geometry - the only difference between vacuum and non-vacuum is how the Riemann tensor decomposes (Weyl and Ricci curvature), so I envision it purely geometrically all the way. In that way of thinking, no question of causation arises, you just have ever-shifting geometries. But maybe that’s just weird old me
    1 point
  23. Mechanical analog timer, such as: will be a PITA because you will have to rewind the wheel every time the previous cycle ends.... e.g. 48h The Arduino method will work as long as there is power (if there is no power, the plants also have no light anyway).
    1 point
  24. Buy a smart plug / wall receptacle. Connect it to Alexa similar home automation app. Setup schedule (the bulb and Alexa both do this simply, perhaps as a routine). Then just plug your lights into that junction with the new smart plug
    1 point
  25. I knew. I was just being deliberately stupid. 🤔
    1 point
  26. 1 point
  27. It would be cheaper and more flexible to buy a $5 Arduino clone. e.g. https://www.ebay.com/itm/145160861832 and relay module for $1.5 e.g. https://www.ebay.com/itm/354746987710 You can then control any 110/230-volt electrical system and turn it on or off on demand using a hand-written C/C++ program that you put on the Arduino board. Sample code in the video below. It is very simple. An 8-channel relay for Arduino costs $6 here, so you can control up to 8 different electrical systems with different parameters. https://www.google.com/search?q=how+to+use+relay+arduino e.g.
    1 point
  28. As soon as I saw it I belly laughed. It's also nice that it isn't nasty.
    1 point
  29. There are 7-day programmable timers. You’d only have to reset it once a week. Or do e.g. a 42 hour cycle I think there are 14-day timers, too
    1 point
  30. Indeed. I --and others, you among them-- have said it before elsewhere on the forums, actually. It's the energy-momentum that sources the gravitational field. I also agree with the absence, of necessity, of any causal connection between the Einstein tensor and the energy-momentum tensor.
    1 point
  31. AIkonoklazt has been banned for repeatedly arguing in bad faith and re-introducing closed topics
    1 point
  32. It is surprising to me that the insurance industry hasn't managed to kill DST yet. Whether the actual figure is 20% or not outside of Saskatchewan, the trend does seem pretty universal. https://www.insurancebusinessmag.com/us/risk-management/news/daylight-saving-time-sparks-20-surge-in-claims-46791.aspx "In fact, collision data from 2014 shows a marked 20 per cent surge in claims in the days after the time change."
    1 point
  33. In spite of this, a 'causative relationship' exists operationally, i.e., we can, in principle, manipulate the source and this would affect geometry, but there is no way to manipulate geometry without manipulating the source. The 'symmetry' is broken.
    1 point
  34. If artificial consciousness becomes even more indistinguishable from wet meat computer (biological) consciousness than it already is, does it really matter?
    1 point
  35. Yes, the SMT-VSL and the expanding universe theory are equivalent. This means that there are no observational or experimental differences between these two points of view. If you are seeking to observe differences, then you are really saying that the SMT-VSL and the expanding universe theory are not equivalent because any observable difference is a non-equivalence. If you are abandoning equivalence, then why would matter shrink in preference to an expanding universe? The size of atoms is governed by laws of physics, whereas the size of the universe is not, so one would not expect there to be a constraint on the size of the universe similar to the constraint on the size of atoms. Also, if you are abandoning equivalence, then where specifically is the non-equivalence? That is, what specific observation or experiment distinguishes these two theories? This actually requires you to look beyond the apparent equivalences to something not deducible by a mere change in the point of view.
    1 point
  36. You can’t use the Newtonian kinematics equations if the motion is relativistic. There is no terminal velocity - terminal velocity requires an opposing, speed-dependent force.
    1 point
  37. Let [math]M[/math] be the mass of the non-rotating spherical mass (neutron star but assumed to be non-rotating), [math]R[/math] be the radius of the spherical mass, and [math]h[/math] be the height above the ground at radius [math]R[/math] from which the object of mass [math]m[/math] (measured at height [math]h[/math]) is dropped. Assuming that the collision with the ground is completely non-elastic, the energy [math]E[/math] (also measured at height [math]h[/math]) released is: [math]E = \left(1 - \sqrt{\dfrac{g_{tt}(R)}{g_{tt}(R+h)}}\right) m c^2[/math] where [math]g_{tt}(R)[/math] and [math]g_{tt}(R+h)[/math] are the [math]tt[/math]-components of the Schwarzschild metric at [math]R[/math] and [math]R+h[/math] respectively. Thus: [math]E = \left(1 - \sqrt{\dfrac{1 - \dfrac{2 G M}{c^2 R}}{1 - \dfrac{2 G M}{c^2 (R+h)}}}\right) m c^2[/math] Note that [math]\sqrt{\dfrac{g_{tt}(R)}{g_{tt}(R+h)}} = \sqrt{\dfrac{1 - \dfrac{2 G M}{c^2 R}}{1 - \dfrac{2 G M}{c^2 (R+h)}}}[/math] is the ratio of the mass of an object at [math]R[/math] to the mass of the same object at [math]R+h[/math], the object being at rest at both heights.
    1 point
  38. Previous to JC's humorous response showing a couple of pics of E Warren in a kitchen, there were only two posts. This one by CbharonY, and this one by TheVat. This is how you characterized JC's response I think JC would like clarification as to which of the two posts you believe to be 'legitimate criticism'. And why then deny making that statement ? Was 'appealing to bias justified, or are we going to get more tap dancing ?
    1 point
  39. Does the QFT provide a sufficient answer? It does not. Not in QED, the best current theory.
    1 point
  40. Explain in your own words what this “law of vibration” is, please. Nobody is going to waste their time watching crappy YuoTube videos.
    1 point
  41. We are still discovering how neurons work and it appears to be more complex then anticipated. For example, neurons found to use many types of vesicles to communicate with other cells, not at the synapse. As for neurons being transistors, they appear to be much more than this. And as for your copyable contention, you know more than me, However, as the empty brain articles indicates, we are not quite sure where or if the information is stored in the brain, so how or could we copy it, remains unanswered. Also, I am unconvinced at this moment that AI or robots will one day be conscious. If it was the case, would we, like in lower life-forms that preceded us, have already begun to see inklings of consciousness in our machines? There may be a fine line separating non-living matter and living matter.The film is superb.
    1 point
  42. Really? Bold by me. If a 'scientific article' cites Deepak Chopra as serious witness, then it is not serious scientific article. Maybe you should read Susan Blackmore: in her student days she had an OBE, and she started a career as 'believing' parapsychologist. But her serious empirical investigations turned her into the end being a sceptic, and leaving the field of parapsychology. I can highly recommend Dying to Live: Science and the Near-death Experience and The Adventures of a Parapsychologist. From the Wikipedia article:
    1 point
  43. The question is more how you define mind. And if we use the various definitions and concepts of consciousness and cognitive abilities, we do have a good idea where things located in the brain. In part from lesion studies (i.e. parts of the brain that have been damaged and resulting in cognitive changes), but also with animal models and other approaches (e.g. fMRI). These includes functions like memory, reasoning, recognition, emotions, and so on. We also know that these are dynamic processes, more related to activity than just localization. And due to the complexity we have not (afaik) a unified view how these components all work together. But even if I do not know how car works in detail, I can see that it does not work without a motor.
    1 point
  44. My first thought was that it’s a clever social media marketing ploy to promote the Elon Musk SpaceX global internet network Starlink project. Just a random guess, though. Regardless, ‘it’s the season:
    1 point
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