According to Albert Einstein\u2019s theory of relativity no object can be accelerated up to or faster than the speed of light. Even approaching that speed causes very strange things to happen, according to the theory: the object becomes more massive, approaching an infinite mass the closer that it gets to the speed of light, it shrinks in the direction of motion, and time slows down.<\/p>\n\n\n\n
Length Contraction<\/strong><\/p>\n\n\n\n One would\nnot ordinarily think that an object\u2019s length would be affected by how fast it\nis moving, but that is exactly what is purported to be the case in the theory\nof relativity. There is some experimental evidence that is used to support\nthis, and other scientists in addition to Einstein argued for it, most notably\nHendrik A. Lorentz. (Einstein even refers to the calculation of it as the\n\u2018Lorentz Transformation\u2019.) The idea seems to have originated with an Irish\nphysicist named George Francis FitzGerald in 1893. FitzGerald said that all\nmatter contracted in the direction of its motion and that the amount of\ncontraction increased with the rate of motion. He believed that all measuring\ndevices, even human sense organs, would also be \u2018foreshortened\u2019 in the same\nway. (This was originally meant to explain why they could not detect the\naether.) For some time the phenomenon was even referred to as the \u2018FitzGerald\ncontraction\u2019. He worked out an equation for it, and knew that it would take\nvery high speeds for the contraction to be significant. At half the speed of\nlight it would be a 15% contraction, at 7\/8ths the speed of light it would be\n50%. At exactly the speed of light its length would be zero. Since there can be\nno length shorter than zero, FitzGerald concluded that the speed of light must\nbe the greatest possible velocity.<\/p>\n\n\n\n Lorentz\nbuilt upon FitzGerald\u2019s idea. He reasoned that if the charge of a charged\nparticle was compressed into a smaller volume the mass of the particle would\nincrease. Lorentz presented an equation for this mass increase that was similar\nto FitzGerald\u2019s equation for shortening. At half the speed of light the mass\nwould be increased by 15%, at 7\/8ths the speed of light it would double, and at\nthe speed of light its mass would be infinite. Lorentz thought that it would be\nimpossible for an object to exceed the speed of light as well because nothing\ncould have a greater than infinite mass. These equations are so closely related\nthat they have sometimes been lumped together as the \u2018Lorentz-FitzGerald\nequations\u2019.[1]<\/sup><\/a><\/p>\n\n\n\n All of this is very similar to the views espoused by Einstein in the special theory of relativity. Many sources omit the history of how these ideas developed over time, which gives the impression that Einstein came up with it all entirely on his own. I do not necessarily fault him for that, because he does give Lorentz, Hermann Minkowski, and others credit for their contributions to the theory in his own writing. (Although he only briefly mentioned FitzGerald; he could have said more about him. He definitely should have cited Poincar\u00e9 as will be discussed below.) It is often the case that new theories build upon and refine the work of those that came before. But it is misleading to present the theory as though Einstein came up with it all himself in one great stroke of genius.<\/p>\n\n\n\n I am not\nactually surprised that there is some experimental data that supports length\ncontraction: if indeed the speed of light is constant then one would expect\nthat when an object is traveling at near that speed it would affect how the\nimage of that object is perceived by the viewer. Where these gentlemen and\nthose who followed them have gone wrong, however, is in assuming that the\nobject itself shrinks when in reality it is just the image that becomes\ndistorted.<\/p>\n\n\n\n We have to\nremember that we do not actually see objects themselves, what we see are light\nwaves bouncing off of those objects. A flat mirror image can look almost\nexactly like the real three-dimensional object because of reflected light. My\nexplanation for the phenomena is that when an object is traveling at high speed\nrelative to light the light waves become compressed in the direction of motion,\nwhich is perceived by the viewer as the object shrinking.<\/p>\n\n\n\n You may\nhave noticed before that when an emergency vehicle passes by you at high speed\nthere seems to be a sudden change in the siren\u2019s pitch. This is an example of\nwhat is known as the Doppler effect. It happens because the motion of the\nemergency vehicle makes it so that the sound waves are closer together when it\nis coming towards you than it would be if both you and the emergency vehicle were\nstationary. This increases the frequency of the sound waves striking your ear,\nwhich is why the pitch sounds higher. When the siren is moving away from you\nthe sound waves are further apart than they would be if you were both\nstationary. This decreases the frequency and causes you to hear a lower pitch.\nThe Doppler effect happens whether it is the source of the sound that is\nmoving, and\/or the observer is moving. If you were in a car and drove past a\nstationary siren the pitch would sound higher as you approached it and lower\nafter you passed it and drove away. (There is a slight difference in how it is\nperceived depending upon whether the observer is the one moving, or the siren\nis moving, but it would not be very noticeable in most cases.)<\/p>\n\n\n\n I believe\nsomething similar is happening with length contraction: it is really just an\noptical illusion created by Doppler shift. I consider it an optical illusion\nbecause it is just a change in how the object is perceived, not a change to the\nobject itself. It is simply not true that a measuring rod actually shrinks,\nwhich explains why its appearance does not change to an observer who is\ntraveling with the rod. If the measuring rod itself really became shorter as a\nconsequence of its motion that should be apparent to observers within the same\nreference frame, but the theory of relativity says that for those observers the\nlength would look and even be measured the same as if the reference frame was\nnot moving at all. It is only from the perspective of other reference frames\n(where the observer is not moving with the rod) that the rod would appear to be\nshorter. This is an important clue that the \u2018shrinking\u2019 is not a genuine\nphysical effect on the rod itself.<\/p>\n\n\n\n According\nto the theory, the reason that length contraction is undetectable to observers\nwithin the same frame of reference is because the observers themselves would\nalso shrink by an equivalent amount, along with all of their measuring\ninstruments (similar to what FitzGerald said). A man that was 2 meters tall could\nlie down and he would shrink to two centimeters in the direction of motion if\nthe spaceship he was traveling in went fast enough; not only would he survive,\nhe would not even be aware of it, and once the ship slowed down to a speed\nclose to where it was originally he would go back to being 2 meters long and\nsuffer no ill effects from the contraction. If he was standing up rather than\nlying down the thickness of his body would be compressed to practically\nnothing; but there is no fear that his internal organs would be damaged, or his\nrib cage crushed, because they would all shrink by the exact same amount. Then\nit would all go back to normal once the ship slowed down and he would not even\nbe aware that the shrinking had happened. Actually, from his perspective it did\nnot happen, since he and all the observers within that reference frame would\nmeasure everything to be the same length throughout the whole process. <\/p>\n\n\n\n If length\ncontraction really happens to the object itself, how could a biological\norganism survive it? We are talking about being compressed to 1\/100th his prior\nlength. Even if we say that the shrinking does not occur within his own frame\nof reference (it is unclear whether relativity theory would say that or not),\nit seems to me that he ought to be dead, at least from the perspective of\nobservers in the frames of reference where such dramatic shrinking is observed.\nIs he alive in some frames of reference and dead in others? Does \u2018relativity\u2019\nextend that far? But if that were the case he would also have to come back to\nlife in those other frames once his frame slowed down, with no indication that\nhe had ever been crushed down to two centimeters. If you think that sounds\nabsurd I would have to agree, but wouldn\u2019t it be just as absurd to say that someone\ncould be compressed from a length of two meters down to two centimeters and yet\nhave no negative health effects from it? <\/p>\n\n\n\n Another\nclue that this is not a genuine physical effect on the objects is that it does\nnot matter what kind of material the objects are made of, they all supposedly\nshrink by the exact same amount. A refrigerator would shrink proportionally by\nthe same amount as a table or a bed. A measuring stick made of wood would not\nbreak when contracted, even if it went from a meter long to a centimeter, and\nit would shrink by the exact same amount as a measuring rod made of metal. One\nwould think that metal objects would be permanently deformed by the\ncontraction, as they would be if they were crushed in a hydraulic press. The\nmaterial has to go somewhere, it does not just disappear (does it?), so if its\nlength was contracted its thickness should increase, and one would think that\nthis would be a permanent change, even once the frame was slowed down. So why\nwouldn\u2019t a wooden measuring stick break, and why wouldn\u2019t a metal measuring rod\nget thicker as it got shorter, and why would they both magically go back to the\nway they were before once the reference frame was slowed down to its prior\nspeed? What physical mechanism is causing this? <\/p>\n\n\n\n Length contraction\nseems very implausible when it is supposed to be something that happens to the\nobjects themselves, as relativity theory asserts, but if it is just the light\nwaves that are being compressed then it makes a lot more sense. That would\nexplain why everything, no matter what material it is composed of, even organic\nthings, all seem to shrink by the exact same amount, and then go back to normal\nonce the reference frame is no longer moving at such a high speed (because then\nthe light waves would no longer be compressed).<\/p>\n\n\n\n In relativity theory it is thought to be impossible to take a disk made out of stiff material and set it into rapid motion at speeds near the speed of light because it would contract in the circumferential direction (the direction of motion) but not in the radial direction. This would cause the disk to break apart. Einstein acknowledged this implication of his view, and suggested that a way to get the disk into rotation would be to melt it first, then set the molten material into rotation and allow it to harden while spinning. That may or may not actually work: I am not really sure how it would have a chance to harden before the centrifugal forces caused the material at the circumference to fly outward so much that it ruined the shape. Perhaps it would depend on the material, but I think it is unlikely that it would work with molten metal unless you used a form ( maybe not even then), and of course then the same problem would arise with how to accelerate the form up to speed without it breaking apart. At any rate, it does not really matter whether the proposed solution would actually work or not, the reason that I bring it up is that I think it is odd that Einstein and other scientists recognized that the rotating disk would break apart but there seems to be no recognition at all that a measuring rod composed of stiff material, such as wood, would break simply from being compressed in the direction of motion, and that it would obviously kill biological organisms. (As for my own prediction about what would happen with the rotating disk, I do not think that it would shrink or even appear to shrink in the circumferential direction because there would be no Doppler shift from having it spin; the only concern with rotating it that fast would be overcoming the immense centrifugal force; that is the real reason that the disk would probably break apart.)<\/p>\n\n\n\n There are\nmany examples of how our visual perceptions can be distorted. One of these is\nrefraction. If you have a straw or a spoon that is partially in water and\nlaying at an oblique angle (slanted) it often looks like it is bent or even cut\nin half where it enters the water. I watched someone cleaning a pool one time\nwith a net that was attached to a very long pole. The refraction was extreme.\nIt looked like the pole was cut in half right where it entered the water and\nthe part that was in the water looked like it was offset by about four inches\nfrom the part that was above the water, and it looked bent. But of course I\nknew that this was just an optical illusion because I knew about refraction, so\nI never thought that the pole was actually cut in half. Just as I suspected,\nonce he pulled it completely out of the water I could see that the pole was not\ncut in half, and it was extremely straight. One could make a relativistic\nargument about this and say that my observation when the pole was in the water\nwas as good as any other observation, because that truly is what I perceived,\nand I know that at least one other person perceived it that way as well (namely\nthe person who was cleaning the pool, as I commented on it and then we\ndiscussed it) so it was not an inaccurate perception. But I think that it would\nbe wrong to insist that the pole really was cut in half for me at that time\neven if that is what I observed. We know about refraction and what causes it,\nand we know from experience that when we take the object out of the water it is\nnot really bent or cut. But it sure does look that way, because what we\nperceive is light, and since light travels at a different speed in water than\nit does in air, it distorts the image without affecting the actual object.<\/p>\n\n\n\n It is\nwell-known that the Doppler effect occurs with light waves: the red shift and\nblue shift that we see from distant stars is a result of the frequency of the\nwaves being affected by the light source\u2019s motion (and\/or our motion). When the\nobject is not a light source we see it by light that is reflected off of it, so\nthere would probably be no red shift or blue shift, it would simply distort the\nimage. (Because it is not the light source or the viewer that is moving at near\nthe speed of light, it is the object.)<\/p>\n\n\n\n Perhaps\nthis is somewhat like radar and sonar (and\/or echolocation, which is used by\nseveral members of the animal kingdom). A radar set can measure Doppler shift\nquite accurately to determine the speed of an airplane or a car. Police often\nuse a radar gun to determine whether a car is speeding. For stationary radar a\npulse of electromagnetic waves is emitted by the gun in the direction of a car\nthat is moving toward the gun. Some of the waves will bounce off the car and\nreturn to the receiver of the radar gun. Because the car is moving toward the\ngun the waves are compressed and have a higher frequency than the frequency of\nthe original pulse that was sent out. By measuring the difference the radar gun\ncan determine how fast the car is moving. It also works when an object is\nmoving away from the source. In that case the returning waves will have a lower\nfrequency than the original. <\/p>\n\n\n\n There are\nobviously some differences between this and how we see: for one thing our eyes\ndo not emit a beam of light. But there is an important similarity: since we\nknow the formula for how much an image is distorted at particular speeds (the\n\u2018Lorentz Transformation\u2019 which is a refinement of FitzGerald\u2019s equations), the\namount of length contraction could be used to determine the object\u2019s speed,\nsimilar to radar. The \u2018Lorentz Transformation\u2019 is a measurement of Doppler\nshift.<\/p>\n\n\n\n Time Dilation <\/strong><\/p>\n\n\n\n Einstein\nexpanded on the original idea from FitzGerald and Lorentz to also include time.\nHe believed that at speeds approaching c time itself would slow down for that\nreference frame, so the frame\u2019s clocks would run slower in addition to\nmeasuring rods being contracted in the direction of motion. (Einstein used the\nletter c to stand for the speed of light, which was common among scientists at\nthe time he was writing. Lorentz and Max Planck, among others, also used it to\nstand for the speed of light.)[2]<\/sup><\/a> This relativistic slowing of\ntime is sometimes referred to as \u2018time dilation\u2019. I believe that this effect is\nalso because of Doppler shift.<\/p>\n\n\n\n Imagine\nthat we have two spaceships that are stationary relative to each other and are\nexactly one light year apart. At a previously agreed upon time and date one of\nthe ships begins to flash a light signal every 10 seconds. The light stays on\nfor half a second then goes off for the remaining 9 and a half seconds until\nthe next flash. This is like a rudimentary clock. Observers in the other ship\nknow that, as previously agreed upon, the light is set to flash every 10\nseconds, and while both ships are stationary this is exactly what they observe;\nit takes a year for those in the observation ship to begin receiving the\nsignals, but once they do they measure a 10 second interval from the beginning\nof one flash to the beginning of another. <\/p>\n\n\n\n After\nsending these signals for 24 hours, in accordance with a predetermined plan,\nthe ship sending out the light flashes begins to accelerate towards the\nobservation ship while the latter remains stationary. Would you predict that\nthe observers in the stationary ship will see the light flashes occur with\nexactly the same frequency, less frequency, or greater frequency as the other\nship moves towards them in a direct line?<\/p>\n\n\n\n The theory\nof relativity says that the observers will see the light flashes come with less\nfrequency because time slows down for the ship sending out the signals as its\nspeed gets closer to the speed of light. Suppose that they accelerate to half\nthe speed of light and then maintain that as a constant velocity; even though\naccording to their own reckoning of time, which includes all of their ship\u2019s\nclocks, they are still sending out the signals every 10 seconds, because of\ntime dilation it will be judged to be more than 10 seconds by the stationary\nobservers.<\/p>\n\n\n\n But let\u2019s think about this carefully; how could that really be true? If the ship is traveling at half the speed of light then it covers 1,498,962,290 meters in 10 seconds ( c = 299,792,458 m\/s, multiplied by 5, or .5c = 149,896,229 m\/s, multiplied by 10). This means that each time a new light signal is emitted the ship is 1,498,962,290 meters closer to the observers when the new signal begins than it was when the last signal began. Since the ship has already covered this distance during the interval between signals the light no longer needs to traverse it in order to reach the observers. Because the speed of light is a constant, we know exactly how much time it would take for light to traverse that distance: 5 seconds. So, the new signal should reach the observers 5 seconds earlier than it would have if both ships were stationary. This is simply because the ship is 1,498,962,290 meters closer to the observers than it would otherwise be. Thus, the frequency of the light signals would be observed to increase from the reference frame of the stationary ship. It would appear to those observers that there was only a 5 second interval between the beginning of one light signal to the beginning of another. This is not surprising: since the ship is traveling at half the speed of light one would expect that the interval between signals would be cut in half. By the same reasoning, if the ship had a velocity of .8c then the interval between the signals would be cut by 80%, meaning that it would be down to 2 seconds from the beginning of one signal to the beginning of another. This is equivalent to time appearing to speed up as the ship approaches the speed of light, not slow down.<\/p>\n\n\n\n Time would\nappear to slow down if the ship was moving in the opposite direction, meaning\ndirectly away from the observers. If it were moving in that direction at half\nthe speed of light then it would be 1,498,962,290 meters further away from the\nobservers at the beginning of each new signal. Since it takes light 5 seconds\nto travel that extra distance, it will take 5 seconds longer for the signal to\nreach the observers than if the ship was stationary. Thus, to the observers in\nthe stationary ship it would look like the light signals were coming in 15\nsecond intervals. <\/p>\n\n\n\n This\nprobably all seems fairly obvious, and it is, but it is important to realize\nthat this is not what the theory of relativity predicts. If the ship is\ntraveling at half the speed of light then observers outside of that frame of\nreference (who are not going as fast) are supposed to see time slow down for\nit, regardless of its direction. Time dilation is solely a function of speed,\nso it should occur whether the ship is coming directly toward the observers,\ngoing directly away from them, or moving sideways relative to them.<\/p>\n\n\n\n The theory\nof relativity asserts that all physical processes slow down as a reference\nframe approaches the speed of light, even a person\u2019s metabolism. If the ship\nwas moving at .95c the prediction is that a crew member\u2019s metabolism would slow\nto only 4.5% of its normal rate. This would dramatically slow the aging\nprocess.<\/p>\n\n\n\n But it is\nnot really time itself that speeds up or slows down, it just appears that way\nto the observers in the stationary ship because of Doppler shift. If those\nobservers were watching what was happening on board the other ship, either\nthrough a powerful telescope or by watching a live video feed, it would look\nlike things were happening faster than normal if the signal ship was coming toward\nthem. The people would seem to be talking and moving around faster than they\nordinarily would. If a man was growing a beard it would seem to be growing\nfaster than normal, along with everyone\u2019s hair. But we should not assume that\ntime itself is speeding up for them, it is just that the signal ship is getting\ncloser to the observers so the lag time between when something actually\nhappened and when the observers see it is decreasing. Once an observer is close\nto the event that is being observed the lag time becomes nearly nonexistent; in\nour everyday experience we can usually observe something almost instantaneously\nto when it actually happened because the speed of light is so fast. But at\ngreat distances that would not be the case. One can often notice a slight delay\nwhen live interviews or video conferences are conducted from halfway around the\nworld. This effect would have some similarities to that as far as how it would\nbe experienced but it would be much more pronounced.<\/p>\n\n\n\n Once the\ntwo ships were close to each other and both were at rest relative to the other,\nor everyone was on the same ship, the two crews would find that exactly the\nsame amount of time had passed for them both. No one\u2019s metabolism would have\nactually slowed down or sped up. Everyone would have aged by the same amount,\nand it would be no different than if they had all remained stationary in the\nsame reference frame the entire time. While it would have appeared to each crew\nthat the clocks of the other were running faster or slower than their own\n(depending on the direction of travel) during the experiment, they would find\nonce they were back together that their clocks were fully synchronized. This\nexplains why neither ship\u2019s computer or any of the clocks that they had on\nboard ever detected any slowing of time: it is because time did not actually\nslow down, or speed up, it just looked that way to observers a great distance\naway because of an optical illusion.<\/p>\n\n\n\n If you say\nthat time dilation is an actual physical reality then not only are you saying\nthat time slows down for the ship giving the signals, but also that time speeds\nup for other reference frames. That is actually a more accurate way of\nexpressing the claim because observers on the signal ship always judge the\nlight flashes to be occurring at the exact same rate of 10 seconds. The signals\ndo not slow down, according to them. So, rather than saying that time slows\ndown for the signal ship, we should say that time speeds up for the other\nreference frames, including the observers in the stationary ship. Because their\nclocks begin to run faster than the clocks on the signal ship as the signal\nship increases its speed the stationary observers will judge the same interval\nbetween the light flashes to be more than 10 seconds while it remains 10\nseconds to the observers in the signal ship. But think about it, isn\u2019t that a\nbizarre claim? The stationary ship has not moved at all during this experiment,\nyet its time (along with the time of other reference frames) is altered by the\nmotion of some other reference frame a great distance away? Why?<\/p>\n\n\n\n Moreover, relativity theory is quite unclear about what observers on the signal ship will see as they observe events taking place on the stationary ship. On one hand the theory asserts that inertial motion is relative, so once the ship is moving inertially those observers could just as easily regard themselves as being at rest and the other ship to be moving at .5c. Because of that, the prediction would be that they will see time slow down for what I have been calling the stationary ship. But the theory also says that when the two ships are back together it will only be the crew members from the one giving the signals that will have experienced time dilation, so they will have aged less and their clocks and calendars will have run slower than the stationary ship. So which is it? Either observers on the signal ship see time for the other ship slow down or they see it speed up, it cannot be both. If they really aged less and their clocks ran slower, and this was apparent once the two crews were back together, then it ought to be that way throughout the experiment. But if that is the case then you would have a way of detecting absolute motion; the frames of reference in which time is running the fastest are closest to an absolute state of rest and those that are running the slowest are, or have been moving at speeds closest to the speed of light. (Stronger gravitational fields would need to be accounted for, according the theory, but that could be done.) This is something that Einstein would explicitly reject because of the principle of relativity, but the theory is not consistent in what observers on the moving ship will see when they observe events on the stationary ship.<\/p>\n\n\n\n It should\nhere be noted that there is no inconsistency at all if we regard time dilation\nas merely an optical illusion. It is perfectly acceptable to say that when the\nsignal ship is moving away from the stationary ship both will see time slowing\ndown for the other because they are moving further apart, and when the signal\nship is coming towards the stationary ship both would see time speeding up for\nthe other because the distance between them is becoming shorter. It is\nconsistent to say this because we are not talking about actual time, it is just\ntheir perception of events on the distant ship. Because events that happen on\ntheir own ship are very close to them they see those events as taking place in\n\u2018real time\u2019, and the events that are taking place on the other ship as speeding\nup or slowing down depending upon whether they are getting closer to them or\nfurther away.<\/p>\n\n\n\n I doubt\nthat anyone would think that time itself speeds up or slows down for listeners\nwho perceive a change in pitch from the siren when an emergency vehicle goes by\nthem. You could interpret the Doppler effect that way, if you wanted to: One\ncould argue that the reason the pitch changes is because time is moving faster\n(or slower) for those traveling in the emergency vehicle as it approaches the\nspeed of sound than it is for a listener in another reference frame. But is\nthat really the most reasonable explanation of the phenomenon? <\/p>\n\n\n\n Now\nimagine that the ship transmitting the light signals moved horizontally\nrelative to the observers in the stationary ship. This would create an imaginary\nright triangle: one side is the distance between the two ships initially (one\nlight year), the side opposite the observers is created by the path of the\nship, and the hypotenuse is the straight line distance between the two ships.\nAs the ship moves the side opposite the observers and the hypotenuse grow\nlonger. Since the hypotenuse is getting longer we know that the ship is moving\naway from the observers. This means that the interval between the light signals\nwill get longer. It would start off being only slightly more than 10 seconds\nbut the difference would grow larger as it went along. Thus, the observers\nwould perceive time to be gradually slowing down for those in the other ship.<\/p>\n\n\n\n Suppose\nthat after proceeding this way for awhile, the ship came to a complete stop and\nstayed that way for a full 24 hours. The light signals would go back to having\nan interval of exactly 10 seconds. Now imagine that the ship turns around and\nretraces its former path. Once it starts moving the interval between the light\nsignals would be less than 10 seconds because the hypotenuse of the triangle is\nshrinking, which means that the ship is getting closer to the observers. It\nwould take it awhile to accelerate back up to full speed ( .5c), but once it\nwas up to speed the interval would shrink the most when the triangle is the\nlargest; this means that as the ship gets closer to its initial starting point\nthe interval between signals would be getting longer, getting closer and closer\nto exactly 10 seconds. When it reached the initial starting point it would be\nvery close to exactly 10 seconds because this is nearly equivalent to being at\nrest in terms of moving towards or away from the observers. But let\u2019s say that\nit goes past the initial starting point and continues on; then it would begin\nto create an imaginary right triangle on the other side and would begin moving\naway from the observers as the hypotenuse of the triangle (on the other side of\nthe imaginary straight line between the two ships at the starting points) gets\nlonger, and the interval between signals would increase. Once again we see that\nwhen the ship giving the signals is moving toward the observers the interval\nbetween signals decreases (\u2018time\u2019 appears to speed up), and when it moves away\nfrom the observers the interval increases (\u2018time\u2019 appears to slow down).<\/p>\n\n\n\n For the\nmost part, it would look the same to the observers whether the ship giving the\nsignals was the one moving or they themselves were moving and the signal ship\nwas stationary, or if both were moving at .25c so that it is equivalent to one\nmoving at .5c. However, there are some differences, which, while subtle at\nspeeds below the speed of light, become more apparent at or above the speed of\nlight. This will be discussed further in the next section.<\/p>\n\n\n\n The Speed of Light<\/strong><\/p>\n\n\n\n The theory\nof relativity has a really weird preoccupation with the speed of light. There\nis nothing particularly special about it, it is just the speed at which\nelectromagnetic waves happen to propagate. Why not choose the speed of sound\nwaves through air, or seismic waves, or the speed of any other kind of wave as\nthe top speed instead? Do we really think that the speed at which galaxies move\naway from each other is somehow constrained by having to go at some speed less\nthan the speed of light?<\/p>\n\n\n\n Einstein\nand the scientists of his day thought that nothing could exceed the speed of\nlight. This has since been amended because scientists have now found evidence\nthrough the experiments conducted at the various particle colliders that there\ncould be particles, called tachyons, that do actually move faster than light.\nNow the claim is that it is impossible for tachyons to be slowed down to the\nspeed of light and impossible for other particles – the ones that compose the\nobjects we are familiar with – to be accelerated up to or beyond that speed. <\/p>\n\n\n\n Similar to\nLorentz\u2019s view, relativity theory asserts that objects become more massive as\nthey approach c, which is meant to explain why they cannot be accelerated up to\nor beyond that speed; according to the theory, as an object approaches c its\nmass approaches infinity. No amount of energy could accelerate an infinite\nmass. This secondary mass is rather mystical. It is not the regular mass of the\nobject, which relativity theory refers to as the \u2018rest mass\u2019. The so-called\n\u2018rest mass\u2019 does not change depending on the object\u2019s speed. <\/p>\n\n\n\n This whole concept of \u2018inertial mass\u2019 seems ad hoc. Its only purpose is to explain why objects cannot be accelerated up to the speed of light. If that is not true then there is no reason to believe that there is such a thing. If length contraction is merely an optical illusion there is no reason to accept Lorentz\u2019s explanation that the particles become more massive as they are contracted into a smaller space, as they are not actually contracted.[3]<\/sup><\/a> <\/p>\n\n\n\n I do not\nbelieve that objects become more massive as they are accelerated. Experimental\nresults that supposedly indicate this are probably just picking up the\nresistance that the particle is experiencing as it is accelerated. When a\nfighter jet approaches the sound barrier there is increased drag, reduced\ncontrollability, etc. There may indeed be some resistance at the speed of light\nas well, especially for a tiny particle. For a charged particle there could\neven be electromagnetic resistance. It would probably be easier to get a large\nobject with a lot more mass (and therefore more momentum) to actually break\nthrough that resistance, but it would be more difficult to accelerate it up to\nthat speed to begin with. The biggest challenge is actually just that the speed\nof light is really really fast. But I do not think that it would be impossible.\nIn fact, if the human species survives another 5 to 10 thousand years without\nbringing about its own extinction I would not be too surprised if someone\neventually figured out how to do it. Perhaps it will be even sooner than that.<\/p>\n\n\n\n So, the\nquestion naturally arises, what would you see if a spaceship was going faster\nthan light? I mentioned previously that there are some differences in how it\nwould be perceived when it is the observer that is moving versus when it is the\nobject which is being observed that is moving. These differences would become\nmuch more noticeable if we assume that the speed is exactly c, or greater than\nc. It takes a little bit less than eight and a half minutes for the light\nemanating from the sun to reach earth. If the earth was moving away from the\nsun at the exact same speed, when we looked back in the direction of the sun it\nwould seem like nothing had changed. We would be traveling along with the\ncurrent wave and could not perceive any that come after it, so no new\ninformation would be transmitted to our eyes. It is not the case that time\nactually stops, of course; the change happens at the same rate regardless of\nwhen or if it is observed, but when we looked in that direction it would look\nlike everything was frozen in place. Thus, if the observer is moving at exactly\nthe speed of light it would appear as though time had completely stopped in the\ndirection that is opposite her motion ( i.e. behind her); in the direction of\nmotion it would look like time was moving twice as fast as it normally would.<\/p>\n\n\n\n Now\nsuppose that we have a viewer that is stationary and a spaceship that is moving\naway from him at near the speed of light. The viewer would see time appear to\nslow down for that ship and its occupants. It would look like everything on\nboard was happening in slow motion, and the closer that the ship got to the\nspeed of light the slower everything would appear to move. One might think that\nif the ship was traveling at exactly the speed of light everything would be\nfrozen in place and it would look like time was standing still, just like when\nit was the observer that was moving; after all, the light would be moving at\nexactly the same speed as the spaceship so it seems like they would just cancel\neach other out and no new information about what is happening on the ship would\nreach the observer; perhaps if the ship was going faster than c time would even\nappear to move backwards. But this is not the case. Once the light is emitted\nit has its own velocity and propagates from that location rather than the\ncurrent location of the source, so it would eventually reach the observer as\nlong as the observer\u2019s velocity is less than c. If the observer was moving\nfaster than light it would be possible to outrun the waves so that they never\novertake the observer, but even if the object that emitted the light was going\nfaster than c the light itself would still reach a stationary observer at the\nspeed of light.<\/p>\n\n\n\n The\neasiest way to visualize this is to imagine a small plane flying over a lake\nwith someone dropping rocks out the window. The waves created by the rocks will\nspread out at the same rate regardless of how fast the plane is moving. The plane\nmoves faster than the water waves that are created, so the waves never catch up\nto it. If you were walking or running along the shore and you moved faster than\nthe rate at which the waves spread they would never catch up to you either. But\nif you were standing out in a shallow part of the lake the waves would\neventually reach you, since you are stationary. Thus we may conclude that for\nany observer that is stationary or moving slower than the speed of light, the\nlight waves will eventually overtake them.<\/p>\n\n\n\n If an\nairplane is traveling faster than the speed of sound you do not hear it until\nthe sound waves reach you, even if visually you can tell that the plane is far\nahead of the sound waves. If a spaceship was traveling faster than the speed of\nlight you would not be able to see it. Instead, you would probably see\nsomething equivalent to a visual sonic boom. From a great distance this would\nlook like the front end of a cone that was bluish purple at the tip. This is\nsimilar to a Mach cone that forms with sound waves. The sound piles up into a\nsingle shock wave that spreads out in a conical shape behind the plane. If an\nobserver is in the \u2018boom carpet\u2019, or in other words within range of the cone as\nthe plane passes by, they hear the \u2018boom\u2019. (Technically the \u2018boom carpet\u2019\nrefers to where the Mach cone meets the ground, but I think it would be the\nsame effect if the observer was not on the ground.) If an observer was within\nthe cone that I am describing they would likely experience it as a sudden\nintense flash of purplish blue light. Neither this observer nor the person\noutside the cone observing from a distance would be able to see the ship itself\nuntil it slowed down to less than the speed of light and the waves had a chance\nto catch up to it. <\/p>\n\n\n\n If the\nobject did not emit light (which means that we can only see it from the light\nwaves bouncing off of it) there would still be a cone but it would be less\nnoticeable. We can infer that this is the case from the fact that supersonic\nbullets still create shock waves even if they do not emit any sound themselves\nbecause they slice through the air faster than sound; but it is less than a\nsupersonic jet (even accounting for the difference in size) because the roar of\nthe jet\u2019s engines piles up so that the boom is louder and more intense. Based\nupon this, one would expect that a meter long measuring rod that does not emit\nany light itself would not create a flash that is as intense as the one created\nby a spaceship that is itself a light source in addition to reflecting light.\nAll of that light would build up into one wavefront, which could be pretty\nintense for viewers within the cone. <\/p>\n\n\n\n One of the\nreasons that Einstein (following FitzGerald and Lorentz) believed that the\nspeed of light could not be exceeded was that it seemed as though the equations\nshowed that if an object reached the speed of light its length would be\ncontracted to zero. But its true length would not be zero, the zero simply\nrepresents the fact that you would no longer be able to see it. (You would instead\nsee the Mach cone.) The same is true for negative values. The theory says that\nif an object exceeded the speed of light it would have negative or imaginary\nvalues for its length, which seems absurd, and that was one of the arguments\nfor why no object could be accelerated past the speed of light. But the\nmeasuring rod\u2019s length would not really turn negative. Just as length\ncontraction could be used to indicate its speed as it approaches the speed of\nlight this could be used to show how much faster it is going than light. Mach\nnumbers could be described negatively. Mach 2 could be thought of as -1, Mach 4\ncould be thought of as -3, Mach 3.2 as -2.2, and so forth. In this case the\nnegative values represent how much faster the object is going than the speed of\nsound which is set at 0.<\/p>\n\n\n\n Many\nscientists and other intellectuals think that time travel is at least\ntheoretically possible because they believe that time dilation is an actual\nphysical reality, so if you could somehow figure out how to go faster than the\nspeed of light they believe that the time dilation would become negative and\nthis would be a way of traveling back in time. I obviously do not believe that\nmyself because I think that time dilation is just an optical illusion.<\/p>\n\n\n\n If you\ncould travel at speeds faster than the speed of light you could see into the\npast, in a sense, but you could not travel back in time because \u2018past\u2019 and\n\u2018future\u2019 are not spatial locations that one can travel to. In a way, we get to\nlook back in time when we look at distant stars because what we see now is\nactually how they were thousands of years ago rather than how they are right\nnow. We cannot know what they look like right now until the light that contains\nthat information reaches us. If you could move ten times faster than the speed\nof light you could rapidly change your position, which means that if you moved\nin the direction of those stars you would quickly be able to, in a sense, see\ninto the future relative to the earth. One is not really seeing into the\nfuture, of course, all that you would be doing is decreasing the lag time from\nwhen something actually happened to when it is observed, and so it would really\nonly apply for distant objects such as stars in other galaxies; in that sense\nonly would going faster than light allow us to see into the future or into the\npast, and there is a limit even to this. You could only go back to the point of\norigin where the light was emitted. Once you are close to that point you would\nbe able to observe the change almost simultaneously to when it happens so there\nwould be no more \u2018seeing into the future\u2019. \u2018Seeing into the past\u2019 would still\nbe possible by moving away from the light source, but of course you would also\nbe increasing the distance, so it wouldn\u2019t be equivalent to seeing how things\nlooked in the past from the prior vantage point. <\/p>\n\n\n\n Imagine\nthat a spaceship traveled a distance of 10 light years in only 5 years. In that\ncase, observers would be able to see 5 years into the past in the direction\nopposite their motion. It takes light from the sun 10 years to reach that point\nin space, but it only took them 5 years to reach the same point. So they would\nbe able to observe how earth looked 5 years earlier from that vantage point\n(but 5 years later than the date that they left). Now suppose that they went\nback to earth, once again traveling a distance of 10 light years in 5 years\ntime. On the return trip it would seem like events on earth were happening much\nfaster than normal, and, of course, to observers on earth it would seem like\nevents on the spaceship were happening much faster than normal. But once they\nwere back on earth everything would be back to normal and exactly 10 years\nwould have passed for those on earth and those in the spaceship. They would\nfind that the ship\u2019s clocks were fully synchronized with earth\u2019s clocks.<\/p>\n\n\n\n We have\ndiscussed what would happen if an object was actually moving faster than the\nspeed of light, but what if it was the combined speed of that object and\nanother that was greater than the speed of light? Suppose that we have three\nspaceships: one is stationary and is right in between two other ships that are\nboth moving away from it at .7c. We can imagine a coordinate plane and say that\nthe stationary ship is located at coordinates (0,0,0). We will say that the\nother two ships are moving in opposite directions in terms of their x\ncoordinate, and they also move up the y plane at a very very slight incline\njust so that their view of each other is not obstructed by the ship in the\nmiddle.<\/p>\n\n\n\n An\nobserver on the stationary ship will say that both of the other ships are going\n.7c, which would imply that they must be moving away from each other at very\nclose to 1.4c, an apparent violation of the theory of relativity. But the\ntheory has an answer for this. If those on ship A were to measure the velocity\nof ship B the equations that Einstein used say that observers on ship A would\njudge themselves to be at rest, the stationary ship to be moving away from them\nat .7c, and ship B to be going at a speed slower than the speed of light. (He\nuses a \u2018reduction factor\u2019 to ensure that when the velocities of objects are\nadded together they still remain below the speed of light for all observers.)\nThe same would be true if observers on ship B were to judge A\u2019s velocity. We\nhave to remember that in the theory of relativity there is no absolute fact\nabout speed and\/or the timing of events; whether something is moving or at\nrest, or how fast it is moving is all relative; something can only be said to\nbe moving or at rest relative to some other body. From the stationary\nobserver\u2019s viewpoint both ships are measured to be moving at .7c, but observers\non those ships will measure it differently. Thus, according to the theory, none\nof the observers will measure the others to be going faster than the speed of\nlight. <\/p>\n\n\n\n I will\naddress Einstein\u2019s claims about relative motion in the next section, but I\nbelieve that what would really happen in this case is that their observations\nof each other would simply be delayed. There would not be the visual equivalent\nof a Mach cone because neither ship is actually going faster than light.\nSuppose that all three ships emitted a light signal simultaneously: what would\nobservers on each ship see? Observers on the stationary ship would see both\nsignals from the other ships simultaneously. Observers on ship A would see B\u2019s\nsignal long after the signal from the stationary ship, but this is just because\nof the much greater distance that light has to travel from B to A than from the\nstationary ship to A. Once the light is emitted it moves at the speed of light\nin all directions, regardless of B\u2019s velocity, so it would eventually overtake\nA, since A is only going .7c. We see from this thought experiment that when the\ncombined speed of two bodies sums to a value greater than the speed of light it\ncreates a different visual effect than when one of them is actually going\nfaster than the speed of light. <\/p>\n\n\n\n The Principle of Relativity<\/strong><\/p>\n\n\n\n The speed\nof light is important in the theory of relativity in another way. In what\nEinstein calls \u2018the light postulate\u2019 he claims that all uniformly moving\nobservers (which would include those at rest) must measure the same speed for\nlight. In the example that he gave, he said that an observer on a moving train\nwill measure the same speed for light (in all directions) as a stationary\nobserver standing on an embankment next to the train. Well, it is true that\nlight waves always propagate at the speed of 299,792,458 m\/s, or 186,282 miles\nper second in outer space. Just like other waves, light waves expand from the\nsource at the same rate regardless of how fast the light source or the observer\nis moving. But there is something very wrong with the light postulate. It is\nrelated to Einstein\u2019s other postulate, the principle of relativity, in which he\nargues that the laws of physics must be the same in all reference frames.[4]<\/sup><\/a> That may initially sound\nreasonable enough, but he interprets that to mean that no matter how fast a\nreference frame is moving observers within that frame must always judge light\nto move away from them at c, since the speed of light is taken to be a law of\nphysics. So even if the reference frame was moving at .5c, as long as it was\nmoving inertially Einstein would say that observers within that frame would\nalways judge light to move away from them at c in all directions. <\/p>\n\n\n\n In defense\nof this, a physicist would say something like the following: \u2018Light always\npropagates at c, not half of c, regardless of the observer\u2019s motion. So while\nwe might expect the light to slow down for the observers in the direction of\nmotion the principle of relativity would prohibit that.\u2019 <\/p>\n\n\n\n My\nresponse is that it is true that the light would not be measured to slow down\nfor the observer, but that is not the right way of thinking about it. If you\nwere going at half the speed of sound we would not say that the sound wave\nslowed down for you, we would say that you were going half of that speed.\nSaying that the difference between your speed and the speed of the wave is only\nhalf what it would be if you were stationary is not the same as saying that the\nsound waves slowed down. The wave always travels at the same speed regardless\nof whether the observer is stationary, moving along with it, or moving away\nfrom it. The key is simply recognizing that the observer has velocity as well\nrather than considering her to be at rest. Similarly, for a reference frame\nthat was moving at .5c observers in that frame would know that the light is\ntraveling at the speed of light (not half the speed of light), and that is what\nthey would measure, but they would also be able to measure themselves as going\nhalf of the speed of light, and that is the part that is missed. <\/p>\n\n\n\n This is\none of the real peculiarities of Einstein\u2019s theory. He is very strongly\ncommitted to the claim that observers in each reference frame could, and in\nfact must always consider themselves to be at rest, even if according to other\nframes of reference they are moving. This is because he thinks that motion is\nrelative. Because Einstein did not think that there was any such thing as\nabsolute motion or an absolute state of rest he seems to have thought that the\nprinciple of relativity required that the motion of all inertially moving\nreference frames be set to zero from the perspective of that frame. Observers\nin other frames of reference might measure that frame\u2019s velocity to be .5c, but\nit would vary from frame to frame depending on their own velocity. Einstein\nthinks that observers in each frame would consider their own velocity to be\nzero, and the other frames to be moving instead, which explains why he thinks\nthat they would always measure light to be traveling at the same speed in all\ndirections. Since there is no absolute state of rest that one could appeal to\nin order to settle the question he believes that it really does just depend\nupon your perspective.<\/p>\n\n\n\n One may\nhave occasionally had a feeling somewhat like this while traveling in a car. If\nyou did not know better you might think that the signs and everything else\nalong the side of the road were flying past you at 60 mph (about 97 kmh) while\nyou and the car are motionless. According to the theory of relativity, they\nactually are; that is an equally correct way of describing the motion as to say\nthat the car is moving and those objects are stationary. One may be tempted to\nsay that one description is correct and the other only appears to be so, but\nEinstein insists that both are equally correct and that there is no\nnon-arbitrary way of choosing between them. For him there is no such thing as\nabsolute motion, there is only relative motion, and relative motion could be\ndescribed equally well from either point of view.<\/p>\n\n\n\n But that\nis where I disagree. No one really thinks (not for more than a second or two\nanyway) that the car they are riding in is actually stationary while everything\nelse in the world is moving around them. It is extremely unlikely that those in\na spaceship that was moving at half the speed of light would be unaware of\ntheir own motion, even if it was inertial. Not only would the ship\u2019s\ninstruments inform them as to how fast they were going relative to the things\naround them, they would also have felt the acceleration to get up to speed even\nif they did not feel the motion once it became inertial. Unless they had been\nmoving at that speed and in that same direction for their entire lives they\nwould remember accelerating. Einstein treats inertial motion as though it is\nindistinguishable from being at rest, but there are some very clear differences\nthat an observer would notice. When you are moving almost everything else\nrushes past you at roughly the same speed and in the same direction. I suppose\nyou could say that everything else is moving and you are stationary, and that\nmay seem correct to you if you are a frequent drug user, but it seems rather\nimplausible otherwise. Would observers ever really think that was actually the\ncase?<\/p>\n\n\n\n If all\ninertially moving reference frames must always consider themselves to be at\nrest then it seems to me that this would not just apply to light waves it would\nalso mean that you would never be able to reach or exceed the speed of sound\neither (or seismic waves, or water waves, or any other kind of wave) from the\nperspective of your own reference frame because to you that frame\u2019s velocity\nwould always be zero while the wave\u2019s speed is greater than zero.<\/p>\n\n\n\n I do not\nknow whether there is an absolute state of rest or not, but why couldn\u2019t we\njust consider the universe as a whole to be a reference frame? We have no way\nof knowing whether the universe is moving relative to something else outside of\nit (if there is anything outside of it), but for us it does not really matter\nbecause all of the motion that we are aware of and referring to is contained\nwithin the universe. This would be like comparing the motion of objects that\nare contained within a moving reference body such as a train, or an automobile,\nor an airplane etc., to that \u2018rigid body of reference\u2019 (as Einstein called it),\nor the x, y, z coordinate planes associated with that body. If each reference\nframe is considered to be at rest then you could compare the motion of every\nobject within that frame to the frame itself to get an equivalent of absolute\nmotion for all the things within that frame. (One also could not say that the\nwhole frame is moving instead of the object that one is comparing it to, or the\nobservers, since the frame is taken to be at rest.) If you were flying in a\ncommercial airplane you could compare the motion of a pen that one passenger\nwas writing with to the motion of another passenger walking down the aisle, or\nto the motion of a flight attendant at the other end of the plane, which would\nbe the relative motion between those objects, but you could also compare the\nmotion of any of the three to the reference frame itself, and the frame\u2019s\ncoordinate system, to get the motion of that object relative to the reference\nframe. If we do this with the universe we have something similar to Newton\u2019s\nabsolute motion, at least relative to our universe. If we added a time element\nthen we would have the \u2018spacetime\u2019 coordinates of general relativity but they\nwould not be relative, or perhaps I should say that they would be relative to\nthe reference body of the entire universe, which for us is equivalent to being\nabsolute. Observers within the reference frame may perceive events differently\nthan other observers do based upon their position or if they are moving\nrelative to the frame and the other observers are not, but they would be able\nto tell when they are moving relative to the reference frame (since the frame\u2019s\nmotion is zero, any motion that they experience is their motion) and they would\nneed to account for that when interpreting their own perceptions. Whether an\nobject and\/or an observer changes position relative to the reference frame and\nits associated coordinate plane would be an objective fact regardless of how it\nis perceived.<\/p>\n\n\n\n Moreover,\nif we insist that c is the maximum velocity for objects then there would have\nto be an absolute state of rest. We may infer that if you were in a spaceship\nthat was traveling at the speed of light the objects that were rushing past you\nat c would actually be in a state of absolute rest. Now I guess, to be fair,\nthe theory does say that you cannot ever actually reach the speed of light, but\nsuppose it was like absolute zero in that we will probably never be able to\nreach absolute zero, but we can come close to it. If you were traveling at\n.9999c then the objects that appeared to be flying past you at the highest\nspeed would be closest to being in an absolute state of rest. One could at least\nestimate what the absolute state of rest would be, and even if we could not\nfind it precisely we would know that it must exist. And, if all observers in\nevery reference frame always measure the speed of light to be c regardless of\ntheir own motion, as the theory purports, then it seems to me that the speed of\nlight would have to be considered absolute motion. Thus, there would have to be\nabsolute motion and an absolute state of rest, at least relative to our\nuniverse.<\/p>\n\n\n\n To return\nto our prior example, those on board a spaceship moving at half the speed of\nlight would know that light always moves at the speed of light, but they would\nalso be able to measure how fast they were moving as well. This is a really\nimportant point because the only way that it could be true that light always\nmoves away from the observers on board the ship at c in all directions is if\nthey were completely at rest. If we acknowledge that they have a velocity of\n.5c then we would have to say that they would measure the light waves going in\nthe opposite direction as moving away from them at 1.5c and the waves going in\nthe same direction as moving away from them at .5c. Light always propagates at\nc, but that is not what this is measuring; it is a measurement of the\ndifference between the observer\u2019s speed and c, not a measurement of the speed\nof light itself.<\/p>\n\n\n\n There is one distinction that I need to make. If that spaceship moving at .5c is emitting light then that light would move away from the point in space from which it was emitted at c in all directions. Light always expands from the source at the same rate in all directions, regardless of the speed of the emitter, so if the observer was positioned at that point in space from which it was emitted and did not move from that spot after it was emitted then of course that light would move away from them at c in all directions. But that is not what the light postulate is saying, or at least not all that it is saying. The light postulate claims that if the light source is the sun observers on board the spaceship will still measure the sun\u2019s light to be moving away from them at c in all directions even if they are moving away from the sun at .5c, and that is just not true.<\/p>\n\n\n\n We can\nthink of light waves as a sphere that expands from the source at c in all\ndirections in which it is not blocked. Suppose that we have a spaceship that is\ntraveling at .999c and emitting a light signal. The observers in the ship would\nsee the light waves expanding from the source at c, but since they are traveling at .999c, which\nalmost matches the rate of expansion, they would see the light in the direction\nof their motion as moving away from them at .001c and 1.999c in the opposite\ndirection. It would be no different than a jet that is close to going\nsupersonic. The jet is moving at nearly the speed of sound. The speed of the\nsound wave is not affected by the motion of the plane, and it is true that the\nsound waves expand at the same rate in all directions, but that does not mean\nthat the sound waves move away from the pilot at the speed of sound because\nthat would ignore the plane\u2019s motion. To figure out how fast the sound waves\nare moving away from the pilot in the direction of his motion you take the\npilot\u2019s velocity and subtract that from the speed of the wave.<\/p>\n\n\n\n I doubt\nthat anyone would seriously argue that the actual pitch of the sound being\nemitted by a siren is relative when we talk about the Doppler effect. Yet that\nis exactly the pattern of reasoning that is used in relativity theory. One\ncould make a relativity-like argument to say that the Doppler effect is an\naccurate perception from that perceiver\u2019s frame of reference: the principle of\nrelativity would commit us to saying that perceptions from all reference frames\nare equally correct, so you could argue that what one hears when a police car\nor ambulance goes by with its siren on is just as accurate from the perspective\nof that reference frame as the perception of what the siren sounds like from\ninside the emergency vehicle. Who is right about whether the pitch changes or\nnot? The principle of relativity says both are. I will grant that it is not a\nmisperception by either party; other listeners would hear the same thing from\nthat vantage point, so in that sense it is accurate, but come on, we all know\nthat the sound the siren is emitting does not really change in pitch; if there\nwas any doubt of that we could rely on the testimony of those who were inside\nthe emergency vehicle, who would report that it sounded the same to them\nthroughout; yes, I know that they were in a different reference frame, but they\nwere also the closest to the siren, so if the pitch really did change they\nshould have been able to perceive it too. What is the justification to think\nthat the perceptions of listeners in every reference frame are all equally\ncorrect in perceiving things as they really are? This is a fundamental\nassumption of relativity theory that is not justified. To believe that you must\nthink that there are no observer-independent facts about the world, only\nperceptions, and all perceptions are equal. But if that is true then we ought\nto trust the perceptions of a schizophrenic as much as we trust the perceptions\nof a non-schizophrenic. (If there are no preferred reference frames then there\ncould not be any preferred observers within a reference frame either.) Although\na listener not moving with the siren may perceive the pitch to have changed, I\nsay that the actual sound being produced by the siren does not change. The\nsound that is emitted is an independent fact that is not relative to the\nperceiver.<\/p>\n\n\n\n Summation<\/strong><\/p>\n\n\n\n If you\nstep outside of the current paradigm and really think about this objectively,\nwhich is the more plausible explanation of the phenomena, that the actual\nlength of objects is contracted as they approach the completely non-special\nspeed of electromagnetic waves, or that since we perceive things using those\nelectromagnetic waves our perception of the object changes when it is moving at\nnear the same speed? Is it more likely that time itself slows down for a\nreference frame simply because it happens to be traveling at a speed which is\nnear the completely non-special speed of electromagnetic waves, or that the\ntime it takes to perceive change to that reference frame is affected when it is\ntraveling at a speed that is close to the speed of the electromagnetic waves\nthat are used to perceive it? Ockham\u2019s razor is clearly in my favor on this\none.<\/p>\n\n\n\n I am not\nreally questioning the empirical data (at least most of it) as much as I am\nquestioning how that data has been interpreted. But I know that scientists want\nexperimental evidence, so here is how my theory could be tested. As previously\ndescribed, I believe that time would only appear to slow down when the object\nin motion and\/or the observer is moving away from the other. When the direction\nof motion is towards the observer (or the observer is moving towards the\nobject, or both are moving towards each other) time will appear to speed up. If\nthe spaceship giving the signals went right by the stationary ship at .5c the\nsignal ship would appear to the observers on the stationary ship to be\ncontracted in the direction of motion and time would appear to be running\nfaster for it until it went past; then after it passed by the signal ship it\nwould appear elongated and it would seem like time had slowed down for it. This\nis equivalent to the change in pitch that listeners hear when an emergency\nvehicle speeds past them.<\/p>\n\n\n\n For the\ntheory of relativity direction does not matter. Einstein thinks that time\ndilation and length contraction are simply a function of speed, so whatever\ndirection the object is traveling in observers in other reference frames should\nsee time slow down for it and its length contracted in the direction its\nmotion. It seems like it would not be too difficult to test these predictions.\nPerhaps an experimental physicist could devise an experiment to test it even\nnow, if in fact they took my argument seriously enough to do so. If it is not\npossible right now, I would imagine that one day in the not-too-distant future\nit will become a testable prediction as technology continues to advance. [1]<\/sup><\/a> I got most of this information from The New Intelligent Man\u2019s Guide to Science<\/em> by Isaac Asimov. Other sources that I used for other sections include Relativity: The Special and General Theory<\/em> and \u2018On the Electrodynamics of Moving Bodies\u2019, both written by Einstein, as well as Einstein For Everyone<\/em> by John D. Norton, and The Mechanical Universe<\/em> video series from Caltech. In addition to these there were several other online sources and science books written for the general reader, but that was all information that is widely available through many sources, so I don\u2019t think I need to cite them. All of the sources that I used were defending and explaining the theory of relativity so one should be aware that I have drawn different conclusions than the authors of these sources did. You can consult those sources directly to find out how they interpret the data and what their arguments are.<\/p>\n\n\n\n [2]<\/sup><\/a>\nIt is unknown what the letter originally stood for, if anything; they may have\njust picked a letter randomly. But two other possibilities are that it\noriginally stood for \u2018constant\u2019, or perhaps the Latin word celeritas which\nmeans \u2018swift\u2019 or \u2018speed\u2019.<\/p>\n\n\n\n [3]<\/sup><\/a>\nSome sources on relativity use nuclear power as evidence for mass-energy\nequivalence and for \u2018inertial mass\u2019. Nuclear power plants and nuclear weapons\nare obviously a reality, but I think that one can acknowledge that breaking\nnuclear bonds in a reaction releases a tremendous amount of energy without necessarily\nsaying that this proves that an object\u2019s mass increases to infinity when it is\naccelerated up to the speed of light.<\/p>\n\n\n\n [4]<\/sup><\/a> It was actually Henri Poincar\u00e9 who first discussed the principle of relativity in published work. In a book called La science et l\u2019 hypotheses <\/em>written in 1902, Poincar\u00e9 dedicated a whole chapter to it. He said: \u2018There is no absolute uniform motion, no physical experience can therefore detect any inertial motion (no force felt), there is no absolute time, saying that two events have the same duration is conventional, as well as saying they are simultaneous is purely conventional as they occur in different places.\u2019 One can see some very striking similarities here to the special theory of relativity. Einstein claimed that he was unaware of Poincar\u00e9 \u2019s work in 1905, but that seems dubious. The more that one studies the history of relativity theory the harder it becomes to ignore the fact that Einstein obviously \u2018borrowed\u2019 (to be charitable) some key ideas from others without always citing his sources. Many have marveled at how he could have been so productive during that so-called \u2018miracle year\u2019 of 1905; maybe it has something to do with the fact that many of those ideas were not original with him. By the way, speaking of citing sources, I got most of this information at this website: http:\/\/everythingimportant.org\/relativity\/Poincare.htm <\/p>\n\n\n\n David Johnson<\/p>\n\n\n\n 2019<\/p>\n","protected":false},"excerpt":{"rendered":" According to Albert Einstein\u2019s theory of relativity no object can be accelerated up to or faster than the speed of light. Even approaching that speed causes very strange things to happen, according to the theory: the object becomes more massive, … Continue reading
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