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Showing content with the highest reputation on 01/01/18 in all areas

  1. 3 points
    You are taking the wrong idea away from his statement. While there are different time rates for your head and feet (due to gravitational time dilation), both the biological processes we associate with "aging" and chronological time are effected equally. A clock by your head runs just a tad faster than one at your feet and the cells of your head age and metabolize just a bit faster than those in your feet. But in Earth's gravity field and at the height of Humans, this is a really, really small difference. So small a difference that just the random variations between individual cell metabolisms completely swamps it out. There can also be differences in the biological aging rate between individual people. Some people age biologically faster and some slower. But this not mean that biological aging is not equally effected by time dilation. Biological aging is just a product of complex bio-chemistry, which is, in turn, a product of physical processes. And these physical processes are just as subject to Relativistic effects as those that a clock operates by. One reason the most famous of the thought experiments in Relativity uses a set of twins is to eliminate the difference in biological aging between the individuals. The point being that if these two twins lived side-by-side, at the end of any given period they would aged the same chronologically, mentally, and biologically. However, if one of them were to be put in a spaceship, sent 17.32 light yrs away and back at 0.866c, When he returns he will have aged 20 yrs, while his twin that did not take the trip would have aged 40 years. This doesn't matter how you measure time: chronologically, biologically or mentally. In this experiment, we assume that the both twins lived out their time in the same types of environments. (breathed the same kind of air, ate the same types of food, got the same exercise, etc) The only way you could have our traveling twin return and be biologically the same age as his stay at home brother would be to introduce some change to the environment that one or the other lives in that either artificially slows the aging of the stay at home twin or accelerates the aging of the traveling twin. (If our traveling twin drank, smoked, ate all the wrong foods, and didn't get any exercise while his brother lived a healthy lifestyle, you might be able to have them having aged biologically the same upon their reunion. However,there's a limit to how much this can effect the outcome. If we increased the traveling twins speed of 0.99c, you would need to have their aging rates differ by a factor of 7. This would be a bit difficult to pull off with just a change of diet and exercise) The upshot is that time dilation effects operate equally on clocks and the rate at which people age.
  2. 2 points
    If you are asking why time dilation occurs, that is best answered by another Einstein fact, that being that the speed of light is the same for every observer no matter his or her frame of reference. This can be further explained by the following..... http://www.pitt.edu/~jdnorton/teaching/HPS_0410/chapters/Special_relativity_clocks_rods/index.html What happens when a light clock is set into rapid motion, close to the speed of light? It is easy to see without doing any sums that the light clock will be slowed down. That is, it will be slowed down in the judgment of someone who does not move with the light clock. First, we will take the simple case of a light clock whose motion is perpendicular to the rod. The light clock will function as before. But now there is an added complication. The light signal leaves one end of the rod and moves toward the other end. But since the rod is moving rapidly, the light signal must chase after the other end as it flees. As a result, the light signal requires more time to reach the other end of the rod. That means that the moving light clock ticks more slowly than one at rest. Remember the light postulate. It tells us that the light always travels at the same speed in any inertial frame of reference. That the rod along which it bounces is moving rapidly will not alter the speed of the light. Here's an animation that shows a light clock at rest and a second light clock that moves perpendicular to its rod. The light signal in the moving clock chases after the rod. To reach the other end, it covers more distance and, as a result, requires more time. Here's the same animation in larger size in case you have a big screen. If you watch the animation carefully, you will see that the moving light clock ticks at exactly half the speed of the resting clock. That is because the light signal of the moving clock has to cover twice the distance to go from one end of the rod to the other. ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: The article further explains why length contraction also takes place, and why one second always passes at one second per second, within one's own frame of reference.
  3. 2 points
    You asked a slightly ambiguous question and got an answer that matched one interpretation but not the one you are putting on it! The important point here is that time dilation is not an effect on the clock. It can't be. For example, right now you are traveling at 0 km/h relative to your chair (no time dilation) you are also travelling at hundreds of miles per hour relative to Mars (a bit of time dilation) you are also travelling at 99% of the speed of light relative to cosmic rays (a lot of time dilation). Your clock can't be running at multiple different speeds, affected by every relative velocity. It is purely a change in the way one person observes another frame of reference. They won't see your clock running at one sped, your wristwatch running at another and your body clock unchanged. They will measure everything changed by the same, relative, amount.
  4. 1 point
    The daily output of one of those rigs would be 1500 gallons a day or 150 000 gallons in the growing season of a 100 days in length. This is assuming good day conditions and basically using the same resources as present agriculture. Is it worth it? Sugar beet is the highest yielding crop.
  5. 1 point
    That's because the lines connect where the expanding sphere of light is absorbed:/reflected by the top and bottom surfaces of the clock apparatus?
  6. 1 point
    Well you haven't said much about my posts, perhaps you missed them in the barrage. One of them was about observing this 'fixed' clock. The point being that the observation takes time and can't proceed faster than light. This simple fact needs to be taken into consideration on any accounting of what is seen (observed) by two observers in relative motion.
  7. 1 point
    Sure you have been answered, many times right here. Relativity is termed relativity simply because time is relative. Every individual in every situation will feel time pass both mechanically and biologically at one second per second. It is only when one compares his own rate of the passage of time with another, that dilation or discrepancies are noticed. At Earthly based speeds and distances though, the difference in effect is very tiny and was not noticed until Einstein came along. You can rest assured though that it is real and has been verified observationally and experimentally particularly in particle accelerators and also our GPS system..
  8. 1 point
    There is nothing special about biological systems. They brave the way they do because of complex sequences of chemical reactions. Those reaction take place at a rate determined by fundamental processes. We have observed this same processes being affected by time dilation. So there is no reason why biological system would not behave the same as any other clock. The universe was evolving for billions of years before humans developed ways to measure time. So it is pretty clear that time is not a human invention. Our descriptions of what time "is" (philosophy) and ways of measuring it (science) are human inventions though.
  9. 1 point
    Even shorter if you're willing (and able) to measure for longer.
  10. 1 point
    Yeah true enough over a long enough duration taking measurements lol good catch
  11. 1 point
    No it's not. It is detectable to a difference of 20cm.
  12. 1 point
    The rate is not, but the phenomenon is.
  13. 1 point
  14. 1 point
    Just a quick note to say happy holidays from me and all the other staff at SFN -- I sincerely hope you're all having a great break. I'm also going to take the opportunity to replace a failed drive whilst traffic to the site is a bit lower due to the holiday period, so there will be a short amount of downtime tomorrow at around 10:00am GMT (UTC+0).
  15. 1 point
    Happy holidays everyone!
  16. 1 point
    Indeed it may be, if you wish to actually understand what may be happening. Yes. Simply because we have chosen to describe a thing as having three components does not mean that it actually has three components. To be specific, describing the thing via three components may be sufficient to perfectly match the observations, but it may not be necessary. For example, you could determine an object's speed, by specifying the three components of its velocity vector and then using them to compute the speed. Or, you could just measure the speed - a single scalar component - and skip the entire three component description. In effect, this is what the Born rule accomplishes in quantum theory - computing a single scalar component (a probability) from the vector (or spinor) components, that were never actually necessary, but which are in fact sufficient. The problem comes, if you ever try to actually make a one-to-one correlation between the assumed components and the actual attributes of the entity being described by those components (as Bell's theorem attempts to do); because any entity that manifests less than three bits of observable information, will never exhibit the three unique bits of information that would be required to form a unique one-to-one correlation with the three components in the description - resulting in rather weird correlations, if you make the unfortunate decision to attempt to interpret them as being obtained from measurements of an entity that actually does exhibit three measurable and independent components.
  17. 1 point
    Most commonly it is due to promiscuity on their active site. It is assumed that early enzymes had little substrate specificity and were accordingly less effective. Specialization increased both, specificity as well as catalytic activity. In addition, there are compounds (or even just parts ) who are structurally similar and would not be distinguishable for the enzyme (depending on the specificity of the active site).
  18. 1 point
  19. 1 point
    You have to be careful here (and in Science generally) since this has more than one meaning. For any observer time passes normally for herself. She just witnesses it passing differently for others who are travelling at (any) speed relative to her. If they are travelling at the same speed together, however great, no effect will be witnessed. The relative speed is zero. The any effect observed will depend on the relative speed and is so small at to be unobservable at low relative speeds. That is why we say there is an effect at high relative speed. Does this help?
  20. 1 point
    Are you sure? Everything I have read suggests that dark matter has been around as long as matter. One of the lines of evidence for dark matter is the cosmic microwave background (CMB) and that is a lot more than 10 billion years old. The Big Bang model is not an explosion, and certainly not an explosion of matter from some central point. Well, it has. And it is space that has expanded (not matter exploding into space). Space is not made of anything. It is just the distance between things. Which is affected the presence of mass - the effects of this include the thing we call gravity. I don't know if that is true. Everyone agrees we can't know. I don't know what proportion think it is infinite. People pop up on science forums insisting it is impossible for it to be infinite and impossible for it to be finite with about equal frequency. I have never seen a survey of physicists, though. It wasn't an explosion into anything. The universe was once entirely full of hot, dense matter (plasma). The universe expanded and, as a result, the matter cooled and gravity caused the gas to clump into stars and galaxies. There is no "outside". Note that a singularity means that the theory no longer applies at that point - a bit like dividing by zero. There are many variations of the basic Big Bang model. Some of these suggest multiple Big Bang "events" (inflation and expansion) producing multiple universes. These ideas are not really testable but are a natural consequence of the mathematics. For example: https://en.wikipedia.org/wiki/Eternal_inflation However, the universe we can see came from a single Big Bang event. That doesn't work. If there is an even distribution of matter around the universe (and it would have to be evenly distributed because expansion is the same in all directions) then it will have no net effect - the matter pulling to the left will be exactly counterbalanced by the matter to the right (and so on for all directions). Newton proved this a long time ago! That almost certainly won't happen. Nearly all of the matter in the galaxy will continue to orbit without being affected by the black hole (which only makes ups tiny amount of the matter in the galaxy). The gravity of black holes behaves just like any object of similar mass. One the gas and stars around the black hole have been absorbed then there will be nothing else for it to absorb. Actually, you can treat gravity as space falling into a body like a black hole: http://jila.colorado.edu/~ajsh/insidebh/waterfall.html But that's OK because space is not made of anything so it isn't really disappearing or being used up. Not only suggested, but it has now been observed several times. Exciting stuff. This can only happen if the black holes are in orbit around each other. It is a pretty rare event.
  21. 1 point
    Certainly, if you leave Earth at near the speed of light, you will see their clocks running slow. And they will see yours running slow. It doesn't really make sense to ask what will happen at the speed of light because it is non-physical: if you try and apply the theory, you end up dividing by zero and similar meaningless things. Not sure what you mean by "true" but it does tell us that time (and distance) are not fixed measurements, they depend on who does the measuring.
  22. 1 point
    This conversation seems to be going something like this: P1: A well balanced diet is critical to good health. P2: Your problem is you think vegetarianism is the only valid path. P1: No, I don’t. I think it’s important to balance ones diet and include both vegetables and meat. Each have a place in good health. P2: You can’t even name one society that’s survived on vegetables alone. Meat makes us stronger! When will you realize this? P1: Sigh. Never mind. You’re not even addressing my actual comment.
  23. 1 point
    Sorry, but it's far too late for that, imo. The priests have had the pulpit to themselves for quite a while now. Love, kindness, compassion have been replaced by money, power, control in the liturgy. Forget "Judge not lest ye be judged". It's OK to judge someone if you have a lot more money than they do. The Pope golfs a LOT.
  24. 1 point
    Trump is removing our "say" in the Paris Accord. Trump removed our "say" in the Trans-Pacific Partnership. His foreign policies diminish our presence on the world stage. We became a world power by creating an international system of policies that set and drove the pace of life on the whole planet. You don't keep something like that by suddenly pulling in your borders and flipping the bird to the rest of the world. If we paid more than our fair share in strategic partnerships, it was to guarantee nobody doubted who was leading the pack, who was the country to emulate. Trump is ruining all of that, giving away our power and clout, and treating international cooperation like a zero-sum game that hasn't benefited us greatly over the last several decades. Trumps policy in general seems true to his horrible landlord personality. He wants America to exploit, lest we be exploited. He wants the US to be the villain, since villains make more money. He prefers to pursue interests rather than allies, and we lose the power of one of the greatest defining human characteristics, our cooperative nature.
  25. -1 points
    First we need to drain the swamp Dems and Reps. You should understand that polarization is a very old strategy,... We have the very best healthcare on the planet!
  26. -1 points
    Thank you. That means a lot to me actually that I'm not completely crazy! But I guess physics is kinda wrong when they try and describe time in regards to age.