Janus

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Everything posted by Janus

  1. Being open minded

    A common confusion between "time dilation" and "total difference in accumulated time". Time dilation is a direct moment to moment comparison of time rates, while total accumulated time is measured over a non-zero time period. At any given moment, a GPS satellite could measure another GPS clock as ticking faster or slower than its own due to their relative positions in their orbits ( there are other considerations other that just relative velocity according to Relativity in this scenario). But over the course the one orbit, the total accumulation of time for each satellite due to the additive effect of those variations will be the same according to each satellite. Such proclamations that Relativity predicts something other than what is seen as occurring are based on overly simplistic straw-man versions of the theory ( in many cases by not taking into account how Relativity deals with measurements made from non-inertial frames and how this differs from those made from inertial frames.) If Relativity actually made predictions contrary to real measurements, it wouldn't hold its present status in terms of acceptance.
  2. Breathing at high altitude flights...

    Right, it should be in2 Somewhere in the back of my head I was thinking in air volume when I typed that. Bit of a brain fart.
  3. Breathing at high altitude flights...

    I was referring the 3000 ft elevation reading Externet got on his altimeter while in flight. This just means that the cabin pressure was at a 3000 ft equivalent pressure and thus had an equivalent oxygen partial pressure
  4. Breathing at high altitude flights...

    Compressing the outside air before it is used in the ventilation system raises the partial pressure of the oxygen. The percentage of oxygen doesn't lower with altitude ( it still makes up ~21% of the gas mixture), there just are fewer gas molecules per given volume at high altitude. At sea level the partial pressure of oxygen is ~3 lb/in3. An atmosphere of pure oxygen at 3 lb/in3 is perfectly breathable. (This is what early astronauts used to breathe). At 1/3 atm, the partial pressure of oxygen is 1 lb.in3. If you take such air and compress it up to 1 atm, you also bring the oxygen partial pressure back up to 3 lb/in3. At an equivalent pressure of 3000 ft, air is still quite breathable even for fairly strenuous activity, so for sitting in an aircraft it is quite sufficient, as it only lowers the partial pressure to 2.6 lb/in3.
  5. Breathing at high altitude flights...

    50% of the air is brought in from the outside and compressed, and 50% is recirculated cabin air.
  6. Special Relativity - simple questions?

    You are reading a lot into that one section of the statement you highlighted in bold. For one, his use of the word "see" is ambiguous. Generally, when when physics uses the word "see" when discussing relativity, they do not mean "visually", but rather after accounting for things like light propagation delay. An similar thing is done in the ruler example given. If you were to visually look at the two rulers in the example, one could be closer to you than the other, in which case, perspective would play a role in which ruler "looks" shorter than the other. In the example, the perspective effect is ignored so that distance between observer and ruler is not considered as a factor. This usage of "see" is used because it focuses on the primary effects of interest rather than the secondary effects of no interest. When "visually see" is the intent, this is usually specified. For the other, he doesn't use the word "always", so there is no way to know exactly what exact scenario he is referring to. Even if he is using "see" as meaning "visually see", there is one situation, where both usages of the word give the same result, this would be at the moment the two observers in each reference frame pass each other and are neither receding nor approaching each other. In this case, they would both conclude and "see" each other's clocks as running slow. Your use of this part of his statement to bolster your argument entirely rests on your personal interpretation of what the author means, rather than taking it within the context of the theory of Relativity itself.
  7. 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.
  8. 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...
  9. 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.
  10. 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.
  11. 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.
  12. 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.
  13. 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.
  14. 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.
  15. 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.
  16. So who's going to win the world cup?

    True, so true.
  17. 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.
  18. 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.)
  19. 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.
  20. 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.
  21. 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.
  22. Length contraction and pressure

    I did say that an observer who, is in an inertial frame, measuring a clock that is accelerating does not have to consider the acceleration, just the speed. This is what the centrifuge experiment shows. It is measuring the time dilation for an accelerating clock as measured from an inertial frame (the lab frame). In this case, the accelerating clock is measured as running slow at a rate that only depends on the speed of the clock. The point I was addressing was that which is measured from within the accelerating frame. If you were riding along with the clock in the centrifuge, and measuring the tick rate of a clock at the axis, you would measure the axis clock as running fast. In the rotating frame of the centrifuge, the relative velocity between the two clocks is zero. There is a potential difference between the two clocks due to the centripetal acceleration which causes the the observer on the end of the arm to measure the clock at the axis as running faster. The magnitude of the tick rate difference will be the same as the time dilation measured from the lab frame. This is different from the case where both observers are in inertial frames with a relative velocity with respect to each other, where they both would measure the clocks in the other frame as ticking slow compared to their own. ravell was trying to argue ( By using the ISS example), that since the clock at the end of a centrifuge would agree with the lab that it was accumulating time at a slower rate than the clock in the lab frame, that this supported his argument that a spaceship moving at a constant velocity would measure a pulsar's clock as running fast. He was equating apples to oranges in terms of measurements made from inertial frames vs. those made from non-inertial frames under the rules of SR.
  23. Length contraction and pressure

    There is not a direct analogy between electromagnetic waves (in vacuum) to water or air waves. Water and air waves have a fixed speed with respect to the medium. While the speed of the waves relative to the water are not dependent of the velocity of the boat making the waves, the speed of the waves relative to the boat as measured from the boat does. A boat could determine its speed relative to the water by measuring the speed the waves it produces moves relative to it. With electromagnetic waves, the speed of the waves relative to the source is always c as measured by the source, and it is always c relative to the receiver as measured by the receiver regardless of the relative velocity between source and receiver. A light source cannot determine its speed by measuring the speed of the light waves is produces relative to itself. No, he will not If he were approaching the pulsar he would measure those ticks at a rate of sqrt((1+v/c)/(1+v/c) and if he is receding from it he would measure the ticks at a rate of sqrt((1-v/c/(1+v/c)). Here v is the relative speed between himself and the Pulsar. It doesn't matter if he considers the plsar as approaching him or himself and the pulsar stationary. A part of this is is account for by the fact that when approaching the distance between the pulsar and observer is decreasing and when receding it is increasing. After you factor this out, you will be left with the time dilation equation and the result that they will measure the pulsar ticks as being slow when compared to his own clock. This is also what he will measure if were to flying past the pulsar at the moment of closest approach (when they are neither approaching or receding from each other). This is known as the transverse Doppler shift effect. Clocks in the ISS are traveling in circular orbit and thus are not in inertial motion (they are in an accelerated frame.) When working from accelerated frames, you can't just take the relative speed into account, but also the acceleration, which in this case always points towards the Earth. A clock which is in an inertial frame, measuring a clock that is accelerating does not have to consider the acceleration, just the speed. As long as both frames remain inertial, they will always measure the clock in the other frame as ticking slow if there is relative motion between them.
  24. A Fallacy about Einstein's Relativity

    To address this scenario you have to take length contraction, time dilation and the relativity of simultaneity into account. For example the initial distances you give are as measured in the frame of the spaceships. This means that they measure the distance between the two planets as being length contracted (shorter than the distance that would be measured by someone at rest with respect to the planets). The distance that the lead ship measures between himself and Planet B, will be longer as measured by anyone at rest with respect to the planets. If he was traveling at 0.9999c relative to the planets, then the distance he measures as being 100 miles, will be measured as 7071 miles in the planet frame. You also say that when The lead ship is 100 miles from planet B, that the Trailing ship is 100 miles from planet A. Again, as measured from the frame of the ships. But this does not mean that the rest frame of the planets will measure The trailing ship as being 7071 miles from planet A when it measures the leading ship as being 7071 miles from planet B. When you say that the distances between the ships and planets are 100 miles at the same time, you are basically saying that if two ships had clocks in them and those clocks were synchronized to each other in the frame of the ships,then those clocks would read the same time (say 12:00) at the moment each ship was 100 miles from its respective planet. However, due to the relativity of simultaneity, according the planet frame, the clocks in the ship are not synchronized with each other. The clock in the trailing ship will read quite a bit ahead of the clock in the lead ship. The planet frame will agree that when the trailing ship's clock read 12:00 it was 7071 miles from planet A and when the lead ship' clock read 12:00 it was 7071 miles from planet B, but it will not agree that clocks on the two ships read 12:00 at the same moment. The sequence of events in the planet frame would go like this: The trailing ship clock will read 12:00 and it will be 7071 miles from planet A. At that time, the lead ship clock will read some time before 12:00 and will be greater than 7071 miles from planet B The distance between the trailing ship and planet A will increase while the distance between the lead ship and planet B will decrease. When the clock in the lead ship reads 12:00, the lead ship will be 7071 miles from planet B. The clock in the trailing ship will read quite a bit past 12:00 and the trailing ship will be more than 7071 miles from planet A. For a thorough analysis you would need to know both the proper distance between the ships (as measured by the ships) and the exact fraction of c the ships are moving with respect to the planets. Length contraction comes into play when you consider the muon frame. For the muon, its clock doesn't run slow, neither is its speed relative to the earth different from what the Earth measures as the muon's speed as being relative to the Earth. Thus the only way it could reach the ground in its lifetime at that relative speed would be for the distance between where it was created and the Earth's surface to be shorter for it than was when measured by the Earth.
  25. In either of these cases, even with warning, people would be more concerned with surviving the immediate after effects of these events, and if any migration were to occur it would be to those regions where these after effects would be minimal. Either of these events are going to reshape the Earth in terms what regions will be more livable than others, and if you can figure out before hand where they will be, everyone would try to get to those places if they could. Short time survival will outweigh any other consideration.