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Janus last won the day on May 6

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  1. Special Relativity - simple questions?

    As I said in my previous post. Relativity makes no such claim when it comes to what an observer will visually see. This is a straw-man argument based on a misrepresentation of Relativity. To explain the difference between what the observer would visually see vs. what he is conclude is happening, we'll use some space-time diagrams. First consider two clocks separated by some distance and stationary with respect to each other. The blue line is our "observed" clock and the green line is our "observing" clock. The scale is such that light, shown as the yellow lines, is drawn at a 45 degree angle. Thus our observer will see light that left the blue clock when it read 1 arrive when his clock reads sometime after 3, and he will see the blue clock read 1 at that time. He also will see the light that left the blue clock when it read 2 arrive sometime after his clock reads 4. However, this does not mean that he will think or conclude that what he sees actually represents what time it is for the blue clock at those moments. That would be shown by the black horizontal lines, which shows that when the green observer sees the blue clock read 1, he knows that it actually reads the same as his own, or somewhat after 3, and when he sees the blue clock read 2, it actually at that moment reads somewhat after 4. Now let's add a third clock, one that is moving at 0.6c relative to the both clocks so that it and the blue clock are closing in on each other. This will be the red line in the following diagram. The light that left the red clock when it read 1 still arrives at the blue clock when the blue clock reads somewhat after 3. But the light that left when it read 2, arrives before the blue clock reads 4. The blue clock observer will in fact see the red clock ticking at a rate twice as fast as his own. But again he will not conclude that this means that this represents what time it actually is at the blue clock. When he sees the blue clock read 1 he will conclude that it reads a bit before 3 at that moment and when he sees it read 2, he will conclude that reads something before 3.5 at that moment, as shown by the black lines. He knows that the light carrying the image of the blue clock reading 2 left the blue clock when it was closer to him than the light carrying the image of it reading 1 left the blue clock. His has to account for this when determining when exactly that light left according to his own clock. As the black line from his clock reading 2 shows, the red clock didn't actually read 2 until sometime after his clock read 2. Thus after accounting for the time it took for the light from the red clock to reach him, he will conclude that the red clock is ticking slower than his own. This is time dilation. Now add yet another clock, this time so that it and the observer are receding from each other, as shown by the light blue line. Again the light leaving when it reads 1 arrives at the green observer when the green clock reads after 3. But the light leaving it when it reads 2 doesn't arrive until the green clock read after 5. The green observer will see the blue clock ticking at 1/2 the rate of his own. But this time, the light blue clock is further from the green when it reads 2 than it was when it read 1, and when the green observer takes this into account, it will turn out that when compared to his own clock, the light blue clock is ticking slower than his own, and by the same rate as he concluded that the red clock is ticking slow. The light blue clock exhibits the same time dilation as the red clock. This is what Relativity says is happening in the real universe, and this is not you you are trying to claim it says ( that an observer will always see a clock as running slow). If you are going to argue against a theory, you have to argue against the actual theory rather than some imagined version of your own creation.
  2. So who's going to win the world cup?

    How? The issuing of a card is up to the official( The injury itself is not the basis of the card), and you can only replace the player without penalty if the injury was the result of a card worthy foul. And we are talking about situations where the player is immediately removed from the pitch and replaced. ( If the player leaves, returns to play, and then decides he can't continue, this rule would not be in force). If the the injury is not the result of a card worthy foul it would not be in force either. So unless you think a team can force the other team to earn yellow or red cards, and by fouling just the players they would want to substitute for...
  3. Matter and Antimatter

    There is no reason to expect antimatter to behave any differently with respect to gravity than "regular" matter. Photons are their own anti-particle, so there is no way to distinguish between light generated by antimatter vs, regular matter. Electromagnetic waves can be generated by accelerating charged particles, and in this respect there is no difference between accelerating a negatively charged electron and a negatively charged antiproton. PET scans work by using isotopes that decay by the Beta+ reaction, in that they emit positrons rather than electrons. These positrons then annihilate with electrons to produce gamma rays which are detected by the scan. If there anti-gamma rays as well as regular gamma rays, why would such a reaction only produce gamma rays? Gamma rays which have an energy equal to the combined mass conversion of the electron and positron.
  4. So who's going to win the world cup?

    If there was one rule change that I could make to the game, it would be that if a player is injured by a foul to the extent that he is unable to continue in the game, and that foul resulted in a yellow or red card being issued to the player committing the foul, then the injured player's team should be able to replace him without using up one of their allowed substitutions.
  5. If you plot bacterial growth rates vs. temp, you find that the slowest rates are at low temps and high temps, with the range most people would consider "tepid" being where the highest growth rate occurs.
  6. So who's going to win the world cup?

    That's how they do at the youngest level of youth soccer ( though they reduce the number of players to 6 to a side.) They also reduce the size of the goal down to ~8 feet. Of course, at this level, the game consists of 12 kids all bunched up around the ball kicking it back and forth, and if the ball happens to pop out and score a goal, so be it. Though one time My daughter got a clear solid kick on the ball and it rolled 3/4 the length of the pitch to score a goal. But to be fair, the field is short at that level and the ground had a definite slope in that direction. ( At this level, you played wherever there was enough free space to mark out a playing pitch with cones.) It wasn't an overly strong kick, but with the help of the slope, it rolled just fast enough to keep ahead of the all the girls chasing after it and by luck more than anything else, passed between the cones marking out the goal. As for the teams left, England is the team getting the support of our household, just because one of my wife's grandparents was from there.
  7. Special Relativity - simple questions?

    SR does not claim that such an observer will always see the Earth clock run slow, if by see, you mean what his eyes or instruments directly record. In this usage of see, he will see it run at a rate of T = To ((1-v/c))(1+v/c))1/2 where v is positive if Earth and the Observer are receding from each other and negative if they are approaching each other. A factor contributing to this observation is the the distance and thus the propagation time for signals is constantly changing, getting longer when receding and getting shorter when approaching. This factor works out to be c/(c+v) When you factor this out of the first equation you are left with the time dilation equation. This means that there are two things to consider: what you see happening to the Earth clock, and what is happening to the Earth clock. So while while receding from the Earth, the observer will see the the 1000 Hz signal as being 500 hz and the Earth clock as ticking 1/2 as fast as his own,. Taking into account the effect of the increasing distance, he will determine that the Earth clock is ticking 0.8 as fast as his own. He will meet up with the object when his own clock reads 1.01.2022 (as the distance between Earth will be only 1.2 ly as measured by him and this is how long it takes to traverse this distance at 0.6c.) He will see the Earth clock reading 1.01.2021, but determine that it is 8.07.2021 on the Earth at that moment. Now at first, you might be tempted to think " But wait, if he sees 1.01.2021 on the Earth clock, and the Earth is, according to him, 1.2 ly away, wouldn't that mean that it should be 3.15.2022 on the Earth by his reckoning?" This is not the case. The light he is seeing at that moment left Earth at a time when the distance between them was less than 1.2 ly, so the time it took the light he is seeing took less than 1.2 years to reach him from the Earth. Now he accelerates in order to come start the trip back towards Earth. We will assume a minimal acceleration period. Now this is the part where people tend to get tripped up. After he is done and is now approaching the Earth and not receding, we will assume that he still reads 1.01.2021 on the Earth clock by visual means. However, he will no longer conclude from this that it is 8.07.2021 on the Earth. Instead he will conclude that it is 6.05.23. During the return trip he will see a frequency of 2000 hz from the signal and the Earth clock tick twice as fast as his own. But again, taking into account the decreasing distance effect, he will conclude that the Earth clock is ticking at a rate 0.8 as fast as his own. Thus he will see the Earth clock tick from 1.01.2021 to 1.01.2025, but conclude that it ticked from 6.05.23 to 1.01.2025 during his return leg. (see will see it tick off 4 years, but conclude that it ticked off 1.6 years. Again, it all come back to what happens during that acceleration period. As far as anyone at rest with respect to the Earth is concerned, nothing special beyond the standard SR effects take place. But for the observer actually undergoing the acceleration, things aren't this simple. For him, the rate at which clocks run depend on which direction they are from him relative to the acceleration he is undergoing and the distance from him in that direction. Clocks in the direction of the acceleration run fast, and those in the opposite direction run slow (beyond what he sees. This even effects clocks that share his acceleration. A clock in the nose of the Ship will run fast and one in the tail will run slow. ( in this case, since there is no changing distance between himself and the clocks, what he sees, will be in perfect agreement with what is happening to the clocks. While this may seem to be at odds with common sense, it is how a Relativistic universe works. A problem with your questions is that they only deal with particular points of the whole scenario without taking in the whole picture. It like comparing two men walking and only considering where they end up. Below we have the paths of two men, Red and Blue, over the same interval. If you just look at where they end up, you would conclude that Blue walked a shorter distance because he ends up closer to the starting point than Red does. But when you consider the whole interval, it is clear that Blue walked a further distance. The same thing is true with SR, if you only consider the end results, you are missing what is really going on.
  8. Question in relativity

    If The distance between A and B is d, as measured by someone at rest with respect to these points, then the distance from A to B is D, then D= ~1/7 d, where d is the distance between A and B as measured by someone at rest with respect to A and B. Thus the total difference between L and D in the rod frame is D-L or 1/7d-L If length of the rod as measured from the rest frame of A and B is l, then l = ~1/7 L and the difference between l and d is 1/7 D-l Plugging some numbers in, if L=10 light sec and and d=100 light sec, then D= 14.29 light sec and the difference between the length of the rod and the distance between A and B will be 4.29 light sec according to the rod. And l = 1.429 light sec, and the difference between the length of the rod and the distance between A and B will be 98.57 light sec according to someone at rest with respect to A and B. The problem is that you use the phrase "at this moment", when talking about comparing measurements made in two different frames. And, as I have tried to point out to you before, you have to take the Relativity of Simultaneity into account when making these type of jumps between frames. So the question I'll put to you is: Do you understand the concept of the Relativity of Simultaneity? Until you do, resolution of this scenario will continue to puzzle you.
  9. So who's going to win the world cup?

    While watching a few of the games here in the US I've seen a few car commercials built around the fact that the US didn't make it to the World Cup. In it they have people from other countries giving reasons why fans from the US should root for their country's team. In one, it is a women arguing for Brazil because they have won the most trophies. For me, that would be a reason to root against Brazil. In a case where I have no personal attachment to either team, I always tend to root for the underdog. I'd rather see a team which has never won take the trophy over a team that had already won several times.
  10. So who's going to win the world cup?

    True, so true.
  11. A Fallacy about Einstein's Relativity

    Which you can't simply do in Relativity when you are transforming between two different inertial frames. This is where the relativity of simultaneity comes in. It is your assumption that you can do this simple addition of distances that is the source of your error. You keep assuming that if electron 1 is near terminal1 while electron 2 is near terminal 2 according to the electrons moving relative to the wire at some moment, then according the wire/lab frame, this is also true. It is not. In the lab frame, when electron 1 is near terminal 1, at that moment, electron 2 will be somewhat short of terminal 2. How much short will depend of the relative speed between electrons and wire. I've already shown you where your error is. In essence, you are making a strawman argument. You are arguing from an incorrect view of what the theory actually predicts. Simply plugging numbers into an equation does no good unless you are using the right equation in the correct way for the particular situation.
  12. So who's going to win the world cup?

    I do remember a reading an article a while back that hinted that Russia being awarded as being the host for this World Cup was influenced by some " under the table" dealing. Even having had taken part at sometime can make being a spectator more engaging. I wasn't much of a fan until after my daughter started playing youth soccer, and then a couple of years in, I found myself as assistant coach (Nothing will learn you a game better than trying to teach it to a group of preteen girls). My daughter is even more of a fan, being a season ticket holder for the Portland Timbers, in the "Army" section (The group of supporters who stand and chant throughout the entire game.)
  13. A Fallacy about Einstein's Relativity

    For one thing, the drift velocity for electrons in a wire is not anywhere near a significant fraction of the speed of light. (for a 12 gauge copper wire carrying ten amps it is ~.0002 m/s, which means it would take a single electron over an hour to travel a distance of 1 meter through the wire.) This is different than the electromagnetic field propagation speed through the wire (which is what we normally consider the "speed of electricity"), which is ~0.951 c. Just because you can flip a switch and have a light several meters away come on nearly instantaneously, does not mean that the electron themselves are traveling that fast through the wire. For the other, you are not just using what Einstein provided, You are giving us your own personal interpretation based on an incomplete understanding of his theory. I gave you the explanation as to what Einstein would have predicted the distance between the planets would have been measured as being in the ground frame in the last post. It is 64 light sec. This is completely independent of any measurements made by the ships, nor any length contraction measured in the distance between the ships made from the ground frame. And while time dilation and the Relativity of Simultaneity are not required to make these measurements, they are required to make these measurements consistent with those made by the ships. Why are you so resistant to the idea that your perceived "discrepancies" are due to a your own incomplete application of the theory to the problem.
  14. A Fallacy about Einstein's Relativity

    I did give an explanation for what the Ground observer sees in my post. Perhaps a picture will help. To make it more amiable for an image, we'll use the following parameters. The relative velocity between ships and planets is 0.866c. The distance between the ships is 30 light sec as measured by the ships. The distance between the planets as measured by the ships is 32 light sec. Thus there will be a moment, according the ships, when each ship is 1 light sec from a planet like this: The black line is the distance between the ships, the blue line the distance between the planets and the red lines the distances between ships and planets. Here we will assume that clocks on the ships both read 0 at this moment according to the ships. However, in the "ground" frame, the distance between the ships will be 15 light sec and the distance between the planets will be 64 light sec. Thus in the ground frame there is no moment when the two ships are each 1 light sec from a planet. Neither do the clocks in the two ships every read the same time like it is shown in the above image. When the trailing ship's clock reads ) the trailing clock does not and when the leading ship's clock read zero, the trailing ship's clock doesn't. The following two image shows the moments when the trailing clock reads 0 and the when the leading clock reads zero. At the top we have the moment when the trailing clock reads 0. At this moment, the trailing ship is 2 light sec from planet A. the leading ship is 47 light sec from planet B at its clock reads ~26 sec before 0. ~52 sec later the ships the ship have moved some 45 light sec at 0.866c. Each clock will have advanced by ~26 sec ( they tick at half speed due to time dilation), and we end up with the lead ship 2 light sec from planet B with its clock reading 0, and the trailing clock is 47 light sec from planet A with its clock reading ~26 sec. In between these two moments there is a moment when the ground observer will say that the two ships are equal distances from a planet, this will occur 26 secs after the top image by the ground observer's clock. At this moment the trailing clock will read 13 sec, the leading clock will read -13 sec and the ships will each be ~24.5 light sec from a planet. There are three things you need to take into account, Length contraction, time dilation and the relativity of simultaneity, when dealing with a situation like this, where you start with what is measured in one frame, and then transform to what is measured in another frame.
  15. Length contraction and pressure

    Then the spacecraft is in a non-inertial frame. For the sake of simplicity, we will ignore the gravitational effect of the pulsar. Thus in order to "orbit" the pulsar, the spaceship would have to be constantly thrusting towards the pulsar and thus has a constant centripetal acceleration towards the pulsar. Under SR, the rules for treating observations from a non-inertial frame are different from those for treating observations made from an inertial frame. A spaceship traveling in a straight line at 0.866 c relative to the pulsar will measure the pulsar as ticking at a slower rate. SR predicts that that observer circling the pulsar will measure the pulsar rate as being fast, but one traveling in inertial frame (straight line, no acceleration) at the same relative speed will measure it as being slow. Both these conclusions come from the consistent application of SR to both scenarios. This is because you have to treat non-inertial observers differently than inertial observers. The predictions of SR are perfectly in line with reality. Your personal inability to grasp or refusal to accept this is not an argument against the validity of SR as a theory nor the predictions it makes. This actually argues against your contention. The Earth also orbits the Sun at a relative velocity of ~30 km per sec. For part of The ISS orbit its orbital velocity relative to the Earth is added to this, and for part of it the ISS orbital velocity is subtracted. Thus for part of the time it is moving slower than the Earth relative to the Sun and part of the time it is moving faster. According to your argument, the ISS clock should spend ~1/2 of its time running slower than the Earth clock and ~1/2 of its time running faster. It does not do so.