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Showing content with the highest reputation since 08/19/19 in Posts

  1. 2 points
    I'm a welder. It's a steady income now that I have a family. I failed out of a biochemistry program years ago. The hardest thing I've had to overcome was depression. Hindsight I've learned a lot about the value of education. I'd cut off my arm to go back to school. I have no idea what I would tell myself in the past. And I really think I should know. I didn't make this topic because I wanted to talk about myself. I want to know how smart, successful people came to choose their careers and if anything helped make them into who they are today.
  2. 2 points
    Here is the arxiv article https://arxiv.org/abs/1906.03369 Hrrm how to simplify this. Ok let's give this a shot. In classical physics you have the E and B fields for electromagnetism however in QM those fields are replaced by the probability potentials [math]\phi[/math] and [math]\mathcal{A}[/math] now in regions where the E and B fields are zero you can still have potential via the wavefunction that the [math]\phi[/math] and [math]\mathcal{A}[/math] are non zero This tells us that the QM and QFT subsequently treatments is more fundamental than the classical treatment in that it is more complete in the information of the EM field. In essence the paper helps confirm that the probability wave functions do have a physical and measurable effect through their potentials. For example it's also a key aspect to how a particle wave packet can go through two slits at once.
  3. 2 points
    Someone asked a question the other day that made me realise that there seems to be a parallel between the Heisenberg uncertainty principle (HUP) and Noether's theorem. For example, one conjugate pair of variables in the HUP is energy and time. While in Noether's theorem, the conservation of energy is related to time symmetry. Another conjugate pair is momentum and position. And the conservation of momentum is related to spatial translation symmetry. I assume this is not just a coincidence. So is there a deeper reason? Is Noether's theorem the reason why these are conjugate pairs?
  4. 2 points
    They must spend a fortune on custom-made hand puppets for this type of briefing.
  5. 2 points
    OK let's clarify something here. First consider the following definitions. Mass is resistance to inertia change Energy the ability to perform work. Spacetime a geometric model system with 3 spatial dimensions with 1 time dimension. In physics dimension is an independent variable or value that can change without affecting any other mathematical object. So how does mass curve spacetime. Well GR models bodies in free fall that is without any force applied. Time is given units of length and can be called an interval. This is done by setting c which is constant to all observers and adding a unit of time. So the time coordinate is given units of length by ct. [latex] (t,x,y,z)=(ct,x,y,z)=(x^1,x^2x^3x,x^4)[/latex] the last is in four momentum form for convenience as its useful to model a particle trajectory along the x axis. Now what is spacetime curvature. Well space is just volume... (Very important ) it isn't a stretchable bendable fabric... Those are just analogy descriptive. What spacetime truly means by curvature is the worldline paths for light it us the null geodesic. If you shoot two laser beams in flat spacetime those beams stay parallel. If spacetime is curved then the beams converge for positive curvature and spread apart for negative curvature. This is a consequence of how the mass term affects the time it takes for a particle to go from emitter to observer. That whole resistance to inertia. So let's drop two objects toward a planet. You have the usual Centre of mass. As the objects free fall they do not stay parallel. They will converge upon one another as they approach the center of mass. That what is really meant by curvature the free fall paths are curved. Not the volume of space.
  6. 1 point
    Below the radar ,but with reassurances that steps are being taken to protact the democratic process. To date this reassurance seems to be missing .Can you reassure me?
  7. 1 point
    The thing to keep in mind is unlike say a pressure tank, a battery or a capacitor where energy can be stored and power is transferred at a rate to perform work on some external to the storage device the universe doesn't perform work outside of itself. All the energy is contained within our universe, there is no transfer of heat, energy or mass from outside our universe from inside to outside our universe. Our universe is in essence an isolated system (speaking thermodynamically) an isolated system cannot perform work outside of itself. To put it bluntly in every paper, textbook, article I have ever read on cosmology and the FLRW metric in terms of the universe not once have I ever encountered any usage of power density or even power being involved in any model of the universe I have ever read in 35 years.
  8. 1 point
    No you would not. In fact dark matter is passing through you all the time (although the density of dark matter around the Earth is very low). Just like neutrinos. It would be invisible, because it doesn't interact with light.
  9. 1 point
    Now I am more inclined to think that The volcanic activity could be the most likely factor there is an alternative theory that our sun might had between 2 to 5 percent more mass in the past but solar winds removed the excess. I remember hearing about it a few years ago but took a bit to find a relevant link https://www.google.com/amp/s/www.space.com/amp/14565-earth-climate-young-sun-paradox.html Anyways googling Young sun paradox will pull up some hits one of the more recent suggested solutions is due to higher solar flare activity https://www.google.com/url?sa=t&source=web&rct=j&url=https://ore.exeter.ac.uk/repository/bitstream/handle/10871/31990/NatGeo_VAirapetian.pdf%3Fsequence%3D1%26isAllowed%3Dy&ved=2ahUKEwjWuuDbmNfkAhXK6Z4KHd8MBEMQFjAEegQIBBAB&usg=AOvVaw2oatKbD466MJR4nUI4sD8o
  10. 1 point
    This is a serious question. I'd like to know how you would answer this in a few words. My answer to the question is the purpose of life is to get better, in a few words. "To get better" is evolution, adaption, and survival. If you get sick, your purpose is to get better. If you do well in anything, the purpose is to get better.
  11. 1 point
    LOL anyway, re. "what root psychological cause is there in the rise of atheism in the 20th century free world?" Why assume it is psychological? Why couldn't it be as simple as The more things we find a real explanation for, the less we need a sky fairy to explain.
  12. 1 point
    Examples of extremely long hair are people whose hair follicles do not go through the normal shedding phase. But I suspect your surmise is correct, that because the shed hair doesn't fall away, the dreadlocks can continue to grow indefinitely. Or until baldness sets in.
  13. 1 point
    We don't get in anywhere? We spend most of our time? Again, how does it help to mischaracterize the situation? We do progress, we spend time improving, but a LOT of progress is stifled because so many people claim we aren't doing anything, and they ignore the good that IS being done in favor of complaining.
  14. 1 point
    This is a bit broad as a question. You must keep in mind that there are elements of security, a similar but different focus on privacy, and then depending on the nature of your cloud or business there are also elements of compliance with certain international standards and laws. Even just within the concept of security, you have to consider encryption type, vulnerability to brute force or DDoS attacks, back doors in the code allowing entry or APIs that can extract info, spear phishing and Ops convincing users to click links or share passwords, and even whether or not there's a physical guard at the door of your server stacks or datacenter. There's also concepts of have disaster recovery plans and the ability to transfer to alternate systems in the event of hardware failures, or backup generators in the case of power outages, and how granular the different user permissions models are (admin god-like access versus limited oversight access to subcomponents versus read-only access), etc. Once you get into the topics of privacy and compliance, then things get even more squirrely with GDPR and other regulatory issues from one country to the next, so you really need to narrow your focus, IMO.
  15. 1 point
    Good article in The Atlantic by Pete Wehner about Trump's disordered personality, and how we've got to stop being shocked by the disturbing things he says and does and start working to remove this damaged soul from an office he's completely unsuited for. He's only getting worse.
  16. 1 point
    Mosquitos aren't attracted to the UV lamps in your typical lantern bug-zapper, which limits their effectiveness in that application. However, there are apparently ones that give off CO2, which does attract them https://en.wikipedia.org/wiki/Bug_zapper "Mosquitoes are attracted to carbon dioxide and water vapor in the breath of mammals, not ultraviolet light.[6] However, there are now bug zappers that emit carbon dioxide or use an external bait, such as octenol, to better attract biting insects into the light."
  17. 1 point
    No, transparency of everyday objects such as fan blades is not affected by velocity relative an observer I think it can be explained like this: Lets say that the fan blades cover 50% of the circular area of the fan. 50% is openings between blades. Start the fan and let it rotate fast so that eyes cannot track the movement of the blades, it looks like a blur. Now think of how eyes works. Simply the eyes register photons and by averaging over many photons an image is created and interpreted by the brain*. Noe look from below the fan towards ceiling. Since the fan blades are spinning fast the photons coming from the fan blades and also from the ceiling between fan blades. Since the blades are 50% of the area there is approximately 50% photons from fan blades and 50% photons from ceiling reaching the eyes of the observer. Result would be that brain interprets photons as coming from something like a half-transparent disc. For a fan with a color similar to ceiling and thinner blades the fan could look almost invisible or almost fully transparent. *) very simplified, hopefully correct enough for the context
  18. 1 point
    I saw a cartoon of a guy who said he made a solar powered device that extracted CO2 from the air and produced building material as a by product. The guy he was talking to asked to see it. The first guy pointed at a tree. The problem is finding land where we could plant them.
  19. 1 point
    This is correct. Not entirely sure what you mean. I generated a fewf binomial probability mass functions, with odd or even numbers of trials. With an even number of trials the most likely outcome is an odd number, while for an odd number of trials the most likely outcome is equal between an odd and an even number. We will expect an even number of heads or tails every time we have an odd number of flips. This is a consequence of the combinatorics of the binomial PMF (the n choose k bit). Does this answer your question?
  20. 1 point
    20 miles/sec The sun is 93 million miles away 4.65 million seconds to get from the sun to us. That more than 7 weeks. 14 weeks from the earth’s orbit distance on the other side (ignoring speed changes from gravity) The earth moves more than a quarter of its orbit in that time. Meaning the comet can’t “hide” We would see it. It’s not moving fast enough. The greater danger is an asteroid (not shedding mass and creating a tail) coming at us from the other side. Dark, hard to spot, and not much parallax.
  21. 1 point
    Correct. There are a number diffdrent of things that will contribute to damage such as impact crater, fireball expansion and thermal radiation, ejecta deposition, seismic shaking, and the propagation of an atmospheric blast wave. Different impacts could be threatening due to different contributions from from such factors. I remember* tests that claimed that impact angle is a major factor for the amount of dust ejected into atmosphere, resulting in climate changes. *) cant find the reference now, I’ll try again later
  22. 1 point
    Well first thoughts on your thread. I respectfully suggest you narrow the focus down some. As it stands the subject is enormous - far too big and diverse for one thread. You have concentrated on the Americans, but say you are moving to Europe. You will find matters quite different here. Europe has a long tradition of state sponsored scientific establishments, that have waxed and waned in importance over the centuries. The UK was the exception. Until the end of WWI, the main impetus was privately developed (sometimes will royal encouragement) and quite a different structure developed. The only real exception came from a military direction. The fifty years following WWI saw the establishment of state scientific undertakings such as the Road Research laboratory, The Building Research Establishment and many others. Sadly during the following fifty years governments of both 'right' and 'left' have steadily dismantled / privatised these operations as well as the ones with military beginnings such as the Hydrographic Office of the Admiralty and The Ordnance Survey. The histories of the Hydrographic offices of the UK and the US are interesting to compare. I once read a book about the sporadic history of the US version and how it suffered from political interference and being a politcal football. The UK HO by contrast enjoyed substantial government support from the 1690s to the 1990s. Significant also is the difference between the US, the UK and European systems of professional qualifications. Most former British Empire states more or less follow the UK pattern, Except India, where the state has stepped in.
  23. 1 point
    So silly that I suspect it's all just a stall by wealthy interests who don't want their taxes paying to help support the masses in such a broad way. They've been delaying the common sense choices for quite a while now with their "too costly" and their "doesn't work", as well as their racism, and their bootstraps, and their snowflakes, and their 2nd Amendment, and their Welfare Queen, and their immigration fears, and all the other tactics they use to keep tax revenues focused on their private investment opportunities. The Cons pulling the strings over here live in private versions of museums with swimming pools on parks with roads and airstrips, and they resent paying taxes for public versions of the same things because they rarely need them. Working folks just don't deserve more than the pay the wealthy give us to work for them. We're such ungrateful bastards to demand good health on top of all the rest they allow us to have.
  24. 1 point
    A tentative 'no'. First (methodological hammer) reaction: when space is empty, there logically also cannot be an observer. So could we ever know? Second: where Newton believed there is absolute space, in which all processes occur, in special relativity this is not the case anymore. What counts are relative positions and velocities. So in this sense, space would be 'spun' by the relative positions of all objects. See for example the discussion between Leibniz and Newton (warning, heavy read; but surely interesting).
  25. 1 point
  26. 1 point
    Listen to the attached file Grewe.3gpp
  27. 1 point
    The speed of an electron is difficult to measure, because sometimes it makes no sense. We usually measure speed by dividing a displacement by the time elapsed. A displacement is defined by two points, and that's where the trouble starts. Confining an electron to a point renders its momentum indeterminate ( Heisenberg Uncertainty ) And since momentum is the product of mass and velocity, you can see how trying to measure an electron's speed renders its speed indeterminate to varying degrees. In modern physics an electron is not considered to be orbiting the nucleus, rather it occupies a probability distribution 'cloud', about and including the nucleus.
  28. 1 point
    Duality has many guises and forms over a very wide range of situations. It is instructive to study some simple types of duality to gain understanding of the phenomenon. This picture, for instance, offers a simple type of duality applicable to the property of shape.
  29. 1 point
    Since the Potassium in a banana isn't going to have any higher a ratio of K-40 than any other natural source of Potassium, if you are thinking in terms of health issues, you have nothing to be concerned about. A person would have to ingest 1000 bananas in one sitting to get enough radiation to increase your risk of death by 1 part in a million. There are no "accumulative" effects either. Potassium is one of those elements that the body carefully regulates. Ingest potassium rich foods, and the body just takes what it needs to maintain levels and the rest is expelled as waste. So you can't get a "build up" of K-40 in your body, and any K-40 in your body is going to be due to the potassium your body needs to function properly. So the only way you could avoid K-40 in your body is to avoid eating all naturally occurring Potassium sources (which encompasses quite a lot of food), and get your potassium via supplements, which have had the K-40 removed. Likely a very involved and expensive process, and unlikely worth it considering the low level risk natural K-40 levels in you body represent. If you are going to fret over that, you'd go absolutely ballistic over the carbon-14 in your body)
  30. 1 point
    There has been discussion of doing this at the exhaust of devices that use fossil fuels, where the concentration is much higher than the ambient atmospheric value. Such as https://www.acs.org/content/acs/en/pressroom/presspacs/2012/acs-presspac-january-4-2012/new-materials-remove-co2-from-smokestacks-tailpipes-and-even-the-air.html Still can potentially be energy intensive, if you are stripping the Carbon from th Oxygen, but you aren't having to move huge volumes of air about.
  31. 1 point
    The biggest single problem is that there's not much CO2 in the air. At 400 ppm (by volume), each tonne of air only contains about 600 grammes of CO2. So you need to shift huge volumes of air, and that takes a lot of energy.
  32. 1 point
    Perhaps a little more detail is needed here ? What is the fluid represented by the blue lines? I am guessing the following: Your text is about the rate of flow or speed of flow of something like water out of a hole in the bottom of the tank (called orifice discharge), using Bernoulli's theorem and the continuity equation. I expect that somewhere your text indicates that atmospheric pressure is sensibly the same at the top and bottom of the tank, because 'h' will be very small compared to the height of the air column causing p0 , the pressure at A1. So the discharge will depend only on the head (h) and density of the fluid in the tank.
  33. 1 point
    THANK You for your comment !!!... I am only asking if a "Fullerite C24" can be done by Natur (or by Humans) having in Mind that the "Cubic Fullerite C24" is made by scientists !!!... ( Is there some reason that prevent the construction of "Fullerite C24" ???... ) https://link.springer.com/article/10.1134/1.1649442
  34. 1 point
    Ok, http://www.einsteins-theory-of-relativity-4engineers.com/LightCone7/LightCone.html the equality with all [math]\Omega[/math] allow to show it. ( and [math]\Omega_0=1[/math] is in input parameters ) we gave both a part of the solution : and so, for [math]\Lambda[/math], it's [math]\Omega_{\Lambda,H}[/math] in relation to [math]\Omega_{\Lambda,H0}[/math] which reflects the evolution of [math]H[/math], the latter also affecting the critical density, both by [math]H^2[/math] ... … certainly, with the exception ( very probably) of the "young" universe. Did I succeed to answer the first question of last quote in this message ( I had miss something ?) ? For 2*, in the near past period and for the whole future, this affects [math]H^2/H0^2[/math] by about 0.1%. It is reasonable to say that, in these cases, the impact is negligible, but it cannot be denied.
  35. 1 point
  36. 1 point
    Beside the fact that Greenland is semi-autonomous which, I presume, would make the legal situation quite difficult, the sale of the Virgin Islands was part of the overall imperialist strategies of the 19th/20th century, which are (at least in the overt form) declining from the second half of the 20th century. While negotiations started in the latter half of the 19th century, various negotiations negotiations ultimately failed, despite the fact that the main interest for the US was imperialist expansion, whereas on the Danish side, decline in the same (as well as increasing cost) were a factor. The sale ultimately happened due to militarist threats from the US. Drawing parallel to current political situations are, tenuous at best (hopefully). Because it is either that or things have gone really insane.
  37. 1 point
    There’s a lot right with your post (which is admittedly more philosophical than astronomical... don’t feel hurt if mods move it). A few points stand out to me: - We ARE different now than before. Every cell in our body is always getting recycled. I think the average to complete this for every single cell is 8 years. You’re not even exactly the same person reading this as you were when writing that original post. You’ve drank water, eaten food, the connections in your brain have been pruned and reinforced, the bacteria in your belly has evolved countless different colonies. Change is the only constant. - Infinity IS hard for our human minds to grasp. We evolved counting seeds and arrow head and antelope. We can barely conceive of thousands or millions, let alone infinities. With that said, it’s important to recall that infinity is just another abstraction. A useful tool in math. It’s not somehow magical and doesn’t make impossible things possible. It’s another type of number. - Probabilities DO get really interesting when considered over vast epochs of time. The probability that something unlikely will happen changes when considered in the next 5 minutes, 5 days, 5 months, 5 years, 5 centuries, 5 millennia, 5 infinities... Its easy to speculate that another “you” could exist, but the amount of time required is likely several times older than the universe itself. - Not everything can be compared to a roll of the dice. If you roll a dice enough times, you can achieve nearly any combination of results. In our reality, however, certain rules apply. Certain chemicals attract and repel to form certain molecules. Certain forms are more successful in an environment than others and evolve more successfully. Certain forces apply, and all of this is well before you get to the level of complex organisms and life forms, or even cultures. Given enough time, nearly anything is possible, if considered within the rules of the system. The main problem here is the amount of time required for these things is several times older than the entire universe. - Most concepts of reincarnation are pretty silly. We are formed from atoms formed by exploded stars, and we do get recycled by other organisms when we die. Our molecules decompose or get eaten by a beetle or burned into the air or absorbed by a mushroom or a tree. In that sense, we reincarnate, sure, but much like you’re not even the same person now as you were when you wrote that post, you’re most certainly not the same “person” after death as you were while alive... while you were “the universe expressing itself as a human being for a little while.” I probably missed the important parts of your question. Sorry for that. These are just a few thoughts off the top of my head. Thanks for letting me share them with you and for the opportunity to do so presented when you asked your kind thought provoking questions. Not all questions have answers, but that doesn’t make it any less fun discussing them. Cheers.
  38. 1 point
    The big bang had a beginning. The question is what was before the big bang? And what is beyond the range of the big bang?
  39. 1 point
    The best thing you can do at this point instead of posting more threads and more posts of your own for the the next week or so, is read through Janus’s posts on this forum in various threads. Do yourself a favor and do as I suggest.
  40. 1 point
    The only centers and boundaries we can logically speak of, is the center of our "observable universe"...which of course anyone can legitimately claim, from wherever he is. While knowledge and data of BB model only goes back to t+10-43 seconds, cosmologists are able to reasonably speculate re those early times. During those early times, the four forces we know of today were united in what was called the "Superforce" As space expanded and temperatures and pressures dropped, this superforce started to break up or decouple, gravity being the first. This created what we call phase transitions and false vacuums. eg: the phase transition of ice to liquid water. These false vacuum states may also be responsible for the Inflation epoch. http://cse.ssl.berkeley.edu/bmendez/ay10/2002/notes/lec19.html During this epoch as temperatures and pressures continued to drop, excesses of energy went into creating our very first fundamental particles, quarks, electrons and such. At three minutes the first atomic nucleus was formed [protons and neutrons] The rest is pretty reliable history. The universe over large scales is homogeneous and isotropic. The same can be applied the the expansion rate...that is, it is only applied over large scales.
  41. 1 point
    I can understand how it may have seemed hasty without the added perspective of what was happening behind the scenes. As mentioned a few times already, after closing it staff discussed the closure and the member was contacted. We considered reopening the thread if we believed the member was hoping to participate in genuine discussion. They weren’t (as per PM), so it stayed closed. It wasn’t a spur of the moment decision, nor was it irreversible. I’m not sure what else there is to say on the matter. We take these things case by case, and a lot of staff discussions and interactions with members are not made public. That isn’t going to change. SFN is not a conspiracy forum, nor is it a make up whatever BS you want and call it science forum. We give a lot of leeway to people to post and defend their ideas, but we have to draw a line somewhere. If we identify early on that a poster has absolutely no interest in participating in rational discussion, why should we let it continue? That runs completely counterintuitive to the spirit of the forum, and has no place here.
  42. 1 point
    Bill Nye saves the world, S1E1: one of the panelists, an engineer, claims the entire world energy consumption could be covered completely with regenerative energy. We have the technology and the resources. And it would only cost a few hundred billion dollars. The Gross World Product is in the vicinity of 100 trillion dollars. If we consider that it will take 10-20 years to realize this if we commit to this, it would be a negligible fraction of our global economic power.
  43. -1 points
    What law of Physics are you trying to protect with your breasts now?
  44. -1 points
    Shooting electrons at a surface is supposed to satisfy my question of what happens when you shoot two matter waves at each other?
  45. -1 points
    I'm not going to do math, and honestly I really don't feel the need to. You're just annoying.
  46. -1 points
    Because, when there are 1000001 electron and 1000000 positrons (in fact, there is mostly photons in the result of interactions I suppose), and the interactions conserve charge, there while always be 1 electron more. That's simple law of big numbers. So you while never detect durably "2" electrons. NO. I don't. My model give the same results, because there are a lot of particles in the void and what you observe is the global effect of all those particles. I'm really starting to wonder if you even understand what you are talking about. I understand (eventhough I don't master math as you pretend you do) what you talk about and say, but you don't seem to understand what I'm saying and what it would imply. If you don't understand what I propose, why do you answer ?
  47. -1 points
    You can disregard whatever you want, and I can tell you something in a clear and understandable way, but I cannot understand it for you. Nothing I said there is flawed, and I did not "omit" anything, because I was not obliged to say everything that is important about science. I was free to emphasize just that what I think is important, and is lacking in that post.
  48. -1 points
    height - width - depth - 3d - all spheres are 3d
  49. -1 points
    Human beings can innovate constantly. Animal innovation is limited.
  50. -4 points
    I will sell, anyone formula of, time of time, for 50 000$, if u know about time of time u will interesting, if u dont understand then, u will think about me like a crazy, but i can say u only tS = n/k * x * tU, after it start theory, for implementation it u need 100 000 $, but if u implementation, it will be new era in science. KZ30722C000016394169.
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