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Showing content with the highest reputation on 11/27/19 in all areas

  1. 2 points
    Well, TakenItSeriously is at least, well, serious. He argues with others, does not claim that we are all idiots, and does not refer to some conspiracy theory why physics hides the truth; and he keeps being polite. But he obviously has a blind spot in his understanding of relativity. I just chimed in in the hope that another formulation would help him to see his error. Others in this thread know relativity much better than I do. (For me, Janus' explanations are becoming legendary...) If people get tired, they can just stop reacting and reading the thread.
  2. 2 points
    This might be possible, if I may offer an opinion, for any number of reasons not apparent form the perspective of an 8-9 year old 20 years in retrospect. It's possible that your vivid recollection of what occurred 20 years ago isn't quite what happen. Time alters our memories and can create false ones that merges imagined experiences with those that are real. If your experience was real and you actually sustained "3 deep knife marks", scars of that experience would likely be visible somewhere on your body today, 20 years later, if they were truly as "deep" as you say. However, you've made no mention of such scars, which could suggest that the sleep injury you sustained was likely not as severe as you might have then perceived 20 years ago, which was likely precipitated and enhanced by the persisting fear an 8-9 year old could have experienced after a night of watching "scary movies". 20 years hence, your memory of the experience was embellished by time. Although, there's strong scientific evidence for the psychosomatic connection between mind and body, which can produce real physical injury, I do not believe this was likely your experience as a 9 year old child particularly without evidence of lingering scarification. I hope this helps.
  3. 1 point
    Top dark matter candidate loses ground to tiniest competitor. The ADMX experiment at the University of Washington uses a strong magnetic field to search for hypothetical dark matter particles called axions. https://www.quantamagazine.org/why-dark-matter-might-be-axions-20191127/?utm_source=quora&utm_medium=referral ADMX’s main magnet produces a field that’s about 150,000 times stronger than Earth’s.
  4. 1 point
    Sorry I even mentioned him, since he's stolen the focus completely.
  5. 1 point
    Mass x velocity. p=mv (nonrelativistic formula) You need to know both. Talking about the momentum in an orbital is usually nonsensical. The whole atom has momentum, but you can't really assign a value to individual particles. They do not follow a classical trajectory. The energy used to create the photon is the energy difference between the electron states. That tells you its energy. There not used to make the photon (i.e. there's no waste involved). The only other energy would be the atomic recoil, and that's tiny for one photon — visible-energy photons cause a recoil of order 1 cm/s. The actual value depends on the exact energy and the atom's mass. (But scatter a few thousand photons and the effects are definitely noticeable)
  6. 1 point
    Pretty much every single medical website. For example: https://www.nhs.uk/conditions/scars/
  7. 1 point
    I know. But I give TakenItSeriously the benefit of the doubt. In one posting he was even trying to clear up where the viewpoints of the different 'discutants' lie. And as I said, you never know when somebody because of a certain formulation or explanation is seeing the light (redshifted or blueshifted...).
  8. 1 point
    Not all vectors have a sign, for example the position vector. Strictly speaking the vector -v is a different vector than v, if both exist.
  9. 1 point
    And I was reacting at: So what does the negative square root physically mean? Then you should realise that the Lorentz factor is dependent on v2, where the Doppler effect is only in the first order dependent on v. That means you must distinguish between Doppler effect and time dilation. So when I have a light source moving fast to me, 2 things happen: Due to its speed there is time dilation, so the frequency of the light source becomes less, i.e. we have a red shift due to its speed. Due to its direction to me, I have a blueshift You must consider both to get the full picture. You must distinguish between what Bob observes, and what he concludes. A blueshift does not mean that there is no time dilation. If Bob takes Alices blueshift in account, he concludes that her clock runs slower compared to his. And Strange reacted: Do you see this is correct? In the example the Lorentz factor is 0.6 independent of the direction. However, the Doppler effect is dependent on the flight direction. But then you said: On which I reacted with my post. What would be the physical difference wen you use the positive solution, or the negative? Again, what is longer: a stick with length 0.5L or one with a length of -0.5L?
  10. 1 point
    Ethan's article is quite correct: we need independent confirmation, with a different method and from some other group. That's more or less understood, though. Important points not mentioned in the original article include the existing kind of experiment which should have seen this, if it were real, and did not ("Lepton colliders producing electron-positron collisions at these relevant energies should have seen evidence for this particle; they have not") and that this group has made new particle claims before which have not panned out.
  11. 1 point
    Ethan Siegel has a critical article about it.
  12. 1 point
    I see...now you recall scars? Did you also awake in a fright and do you recall your parents reaction to your injury? After nearly four decades of private study in pursuit of understanding the nature of mind, consciousness, and dreaming, I can confidently say that the injury you described was likely caused by some influence within your sleep environment rather than your dream. Dreaming is how our sleeping brain synthesize or interpret sensory stimuli it perceives during the periods of arousal caused by its metabolic needs amid sleep. Our brain is the largest consumer, about 20%, of our body's overall energy uptake. Its persistent metabolic needs in sleep causes arousal, which is why dreaming is a kind of consciousness or wakefulness amid the sleep process. Our sensory experiences during sleep can precipitate a cascade of neural activity leading to imagery very much like familiar fragrances that vividly invoke a cascade of mental imagery or long forgotten memories. Cut marks on your body with the precision of a knife was likely produced by something or someone in your sleep environment, which your sleep brain then interpreted as relative to your recent scary movie experience--IMO.
  13. 1 point
    ETs have nothing to gain by being detected by any other civilization. I agree that they would likely mask their presence and use stealth. Aliens that use UFOs with colorful blinking lights would be likely robotic probes to attract attention. The next question is why would they want to be seen?
  14. 1 point
    One can have control of something but still be right or wrong. I see no direct connection between the concepts of "control", "guess", "model", "right" or "wrong". You just seem to b throwing random sentences around. All I can deduce from what you say is that you are suggesting that if one were able to control the weather, then forecasts would always be right?
  15. 1 point
    That cracked me up.
  16. 1 point
    ! Moderator Note I reckon we're done here.
  17. 1 point
    ! Moderator Note The OP hasn’t been back for 6 years. As the original post was nonsensical, I see no point this staying open.
  18. 1 point
    Search for "terminal velocity" on the Internet. https://en.wikipedia.org/wiki/Terminal_velocity Objects which are falling in Earth's atmosphere are reaching their own specific terminal velocity. Human with horizontal body orientation (i.e. parachute jumper) will have different terminal velocity than human with vertical body orientation. "Terminal velocity is the maximum velocity attainable by an object as it falls through a fluid (air is the most common example). It occurs when the sum of the drag force (Fd) and the buoyancy is equal to the downward force of gravity (Fg) acting on the object. Since the net force on the object is zero, the object has zero acceleration.[1]". For human body it's approximately ~220 km/h. So the question is "what is chance to survive 220 km/h hit with the ground".
  19. 0 points
    Studiot - Climate change is what we facing right now - an ongoing, cumulative and irreversible change to the global environment we depend on, with serious consequences for people now living. Geomagnetic pole reversal - if increased movement of the pole is in fact a precursor to pole reversal - does not present a clear and immediate danger. If I understand correctly, these reversals take thousands, if not tens of thousands of years. If our economy and environment are messed up from climate change we will be less capable of coping with other things; it is quite reasonable - imperative - that we take climate very seriously and give it priority. As for destruction of arable land, it is quite closely linked to climate change, both causative and as a consequence as well as being significant in direct, economic and environmental terms; rather than being something that is neglected because of the focus on climate change I think it reinforces the overarching significance of climate change. Seeking a better understanding and modelling of our planet's internal workings to should continue but I see no equivalency or even real relevance to efforts to better understand and address the climate problem
  20. 0 points
    I'd argue the opposite. "No change" is not a baseline or default. It is specific model indicating a type of steady-state situation. Trends up or downwards indicate deviations from it. Thus, if you capture the trend but get the rate wrong it still means that you have captured more mechanisms at work moving away from the stable assumptions (but may be missing or underestimating some elements) compared to a model which predicts no change. Surprise! Quite a few do, actually. I may be misremembering, but I am fairly sure that in the early 90s/late 80s a consensus in the scientific community has formed regarding climate change (wasn't IPCC established around that time)? Obviously some would have been careful about making predictions, but I vaguely remember some being fairly outspoken on that matter back then. After all, it generated enough momentum for the Kyoto protocol, which, considering the power of the opposition, indicates that the science of that time created enough momentum to get politics moving (which is always an astonishing feat). The big issue is that that this type of skepticism denies science and as such there are no valid counter arguments. If folks already decide on what they want to believe there is not a lot of ways to dissuade them. It used to be possible to demonstrate e.g. that their arguments were sponsored by the industrial PR groups. But now these beliefs are so tightly integrated into their political identity, that this would only be perceived as an attack against them, rather than the arguments.
  21. -1 points
    To be brutally honest its Friday evening, Im tired after carying a g damn 200 pound washing maschine from a cellar with steps through a garage and a driveway uphill to a truck with my Father in law who pisses me off and I currently don't care about the polar bears. I'm tired, to a point I'm not even enjoying the drink Im having while my missus has her period, her world is collapsing with every breath she takes while crying and being pissed off at the same time - as far as I'm concerned the polar bears can go extinct tomorrow if no further implications to me and my family - f'em. There have been tens of millions of species on our planet which went extinct, one more or one less, phhh. The thing is that the lady in the clip seems to imply that Polar bears not going extinct = Theres no climate change problem. I hope we both agree that this would be an extremely moronic line of thinking now would it? Please take 30 seconds to look at the link belowe and think about climate change on Earth. I presume you have children, grandchildren or nephews, grand daughters, cousins, the whole shebang. Please look at this and tell me that youre not worried about Homo Sapiens fucking the Earth up for the last 80 years to the point in which it IS a problem and WILL be a much BIGGER one: https://www.worldometers.info/world-population/
  22. -1 points
    Your kidding right? You do realize that when you take the square root of any number you get a positive and negative result right? e.g. √4 = +2 & -2 Besides that the Lorentz factor is not a vector. It doesn't even have units.
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