Martin B previously mentioned that small particles have been accelerated to relativistic speeds. Particle accelerators confirm that attaining ever-higher velocities requires exponentially increasing amounts of energy, with all signs pointing to an upper unattainable limit at c (infinite energy required). More here. There’s no reason to believe that a self-propelled rocket would measure differently from a “stationary” observer’s perspective.
It doesn't. Yes, but it is important to understand why. This is a cosmological redshift/time dilation, not a doppler one. If A and B often appear together it does not prove that A causes B. Time dilation doesn't cause length contraction. This is really messed up. "space" doesn't move - in fact it is not a physical entity - and so is not subject to Lorentz contraction. In your understanding, if I looked out in a particular direction and saw one object receding quickly, and another object at rest would the intervening space be affected by the receding object or the one at rest? Although uttering the words "not motion through local spacetime" you nonetheless seem to understand all time dilation as being the same as that associated with relative velocities. This is not the case. Distant supernovae are (on average) at rest relative to us in terms of their local space-time. However between us and them space-time is expanding. The cosmological redshift is caused by the expansion of intervening space in the time it takes the light to reach us. Time dilation is due to the expansion in the time dimension. Both factors are observed.
Please see my last point below. Sure, but I didn’t say that. Time dilation and length contraction are inextricably linked in relativity (with the exception of cosmology, which is why I’m asking about it). I shouldn’t need to prove here how they are linked. More below. Contraction of an object applies to the space between and within the atoms of the object as well. So space is subject to it. When you accelerate space contracts along your axis of motion in a way that can be measured. For example, relativity suggests you can get to the Andromeda galaxy within a human lifetime while accelerating at 1g. At the halfway point, where you have say 10 years on your clock remaining to reach the galaxy, the distance you measure between the Earth and the galaxy cannot exceed 20 light years (otherwise you’d need more than 10 years on your clock to reach the galaxy, since you’re approaching it at less than c). The distance measurably contracted during your acceleration from 2 million or so light years to less than 20 light years. Neither. But the intervening space between you and anything relative to which you accelerated—the kind you feel—would be affected by you, as described above. It’s OK to consider the supernovae as moving away from us for the purpose of calculating their time dilation. Consider: If the “redshift [is] the same in both views,” and since only the redshift is needed to determine a recessional velocity that, when plugged into the special relativistic time dilation formula, yields the observed time dilation of the supernovae, then it’s okay to understand that the time dilation of supernovae is the same as that associated with typical relative velocities. And if the time dilation of the supernovae is of the special relativistic variety, then the supernovae must be length-contracted as well. And since from the alternate viewpoint space itself is expanding to cause the supernovae’s recessional velocities, then the space between the supernovae and us is also length-contracted. You seem to be describing a time dilation that is Doppler-like in that it occurs only because of the ever-increasing time it takes the supernovae’s light to get to us. But my books say that the time dilation observed about supernovae is a difference in rates of aging as predicted by relativity (to be extra clear: predicted not because of the ever-increasing time it takes the supernovae’s light to get to us, rather because everyone directly measures light’s velocity as c). And there’s no reason for me to disbelieve this given Ned Wright’s Cosmology FAQ comment above. Can you elaborate if you see it otherwise?
MacM – I have to make this quick. I highly suggest to you the book Relativity Visualized. Easy as cake & it addresses all the issues in your last post. But briefly: You can reach destinations in ever-shorter times on your clock as you accelerate; the speed of light is not a limit in that way. Relativity does not deny you, in principle, reaching any galaxy in 1 second on your clock. There need not be any “decoupling” with Lorentz contraction. You just won’t measure yourself exceeding c. See my example to Martin B above regarding a trip to Andromeda. Mass doesn’t increase in a way that increases gravitational pull. One way to view that is that the increase in mass is perfectly offset by the time dilation. That’s been covered in other threads and is also well taught by the book above. What you describe doesn’t fit all the observations. For example it doesn’t explain how once-synchronized clocks can physically get offset (within a tiny margin of error of the amounts predicted by relativity formulas no less). But rather than get into that here, why not read the book first? You seem a layman like myself. I can do much of the math but I’d much rather understand it intuitively and for that I eschew the math, at least initially. The best solution for that method is a teacher who teaches visually. Another good book is Understanding Einstein's Theories of Relativity. For example, if you want to get somewhere in a time on your clock as if you were moving at 10 times the speed of light, the formula is: x/sqrt(1+x^2). So you need to attain 10/sqrt(1 + 100) = 99.5%c. At that speed the space between you and your destination is contracted to sqrt(1 – (99.5%)^2) = 9.95% of what you’d measure when at rest relative to the destination. At 99.5%c, with contraction to 9.95%, you can cover 10 light years (as measured when at rest relative to the destination) in 1 year on your clock. You can accelerate forever with nothing unusual noticed in principle (as you’re using the word “notice”). The non-relativistic acceleration formula gives you the “10c” or “100c” value that you input into the first formula above. No matter what multiple of c you seem to be going (in terms of how fast you’re getting somewhere), length contraction keeps you under c relative to objects you’re passing. No decoupling necessary. Better explained by the books though.
Oops... When i last saw this thread ryans posted a question of who was right with remaining amount of U-235. Now i visit again after few hours and found the whole U-235 blasted-off like a nuke and MacM was grinning at all of you guys. lethe, you really spoiled the party..Please Register or Log in to view the hidden image! you should have given ryans a chance to have SR fun with MacM..
Points. The rocket has a light source attached to the front of it. An observer in the rocket will always measure the speed of the light eminating from the front of the rocket to be c. However, the observer on the rocket, and an observer to whom which the rocket is moving relativistically will disagree on the frequency of the light. As pointed out to me, and on reminiscence due to further studies, gravitational mass does not equal relativistic inertial mass, thus no observed clustering. Obviously this is the case as gravitational force would not fall off as 1/r^2 when say two galaxies are moving apart from one another, as is observed. If it were the case, the universe would rapidly expand and contract in an instant. Obviously this is the case. Face it MacM, the problem isn't with SR but with your inability to handle the conseuences of SR.
Thanks Zanket, Thanks for your response I have posted your book recommendations into favorites and will be looking for copies. I found your post interesting because you make a couple statements which fit my view that others have repeatedly rejected. I even see some areas where I think we are looking at symantics not actual differences. But on the largest scale I have already read many books; including "the elegant universe" by Brian Greene; which I find damn near offensive to intelligent creatures. But I'm sure that is a matter of taste. **************************************************** I was as in every case disappointed in that nobody has come forth and answered the challenges I have made. That is justify the basis for relavistic assumption in absence of using relativity as its own proof. **************************************************** That challenge remains on the MSB. By what basis does one justify imposing limits on independant interial systems physics due to perception of an observer and by what basis does one impose a v=c limit on terminal velocity when one assumes terminal velocites do not exist? (That is v=at in absence of a reference for considering the "Relative Velocity" to another object); in which case it seems that v is therefore always "0" and only dimension has changed. We'll have another party soon I'm sure.
Re: Laughable The thing you fail to realise is that No one in the rocket can measure their relative velocity with respect to the rest of the universe as being greater than c either. As the universe speeds by it will, from the perspective of the Rocket, undero the Lorentz transformations. And not just the individual components (stars etc.) but the entire universe including the distance between the stars. The upshot its that Earth will never have an observed velocity greater than c as measured from the ship. Now, if the ship can't have a greater than c velocity when measured from the Earth, and the Earth can't have a greater than c velocity as measured from the ship, In what manner can you say that the ship has a greater than c velocity?
What the...? What challenges? I didn't see you jumping to answer any of the problems we had with your view. SR does not need defending against the likes of you. Some of the greatest minds in history believe that it correct, but sorry, Mac doesn't believe it because it goes against his intuition. I didn't see you in any rush to show how casualty is not violated if travel faster than c is permissable, nor did I see you try and offer any answer the problem i posed. And i know why you didn't like Briane Greens book, because you didn't understand it. I have a question for you Mac. You used to be an engineer right? Did you ever tell anyone that some parameter or specific component of an instrument wasn't suitable, even would be likely to fail, to here the response "It'll be right"?
The basis is that everyone directly measures light’s velocity in a vacuum as c. Einstein postulated that c is the fastest speed of information flow that anyone directly measures. (By “directly” I mean the light hitting your retina, say, rather than the light crossing a nebula.) No experiment has contradicted the postulate. Yet... From your perspective in your rocket v=at effectively remains true despite the light-speed limit. Suppose you accelerate at 10 m/s^2 for 10 years. Then you’re going 10 * (10 * 365 * 24 * 3600) = 3.15 billion m/s = 10.5c, right? Just one adjustment necessary so that your speed matches the observation that every directly measures light’s velocity as c: plug 10.5c in the formula I gave above. Your velocity becomes 10.5 / sqrt(1 + 10.5^2) = 99.6%c. While you accelerated space along your axis of motion contracted to 9.5% of what you’d measure before you began accelerating. The contraction lets you get to your destination ever faster on your clock by accelerating (that is, as you'd expect by the formula v=at), while staying under the speed limit.
While I can’t address your list because I don’t know about those things, like the Chiral Condensate, I do see your point. But why would I need to know a seemingly more complex alternative to relativity, when relativity already elegantly explains the observations? Shouldn’t I just go with the simplest explanation? All of physics is based on articles of faith. The highest faith goes to the simplest explanation; Occam’s razor. True that relativity cannot be ruled in, which is why it’ll remain a theory. I made a mistake in my previous post. If you accelerate for 10 years, your final velocity isn’t given by the formula in my post, but by a formula within here. I’m still thinking of an intuitive explanation for that.
i beg to differ. 1. atomic clock have been put on a plane and one on the ground. they are precisely synchronized to eachother. the plane travels at speeds of say 500mph and the one on the ground just sits there. when the plane lands, the clock is off by a few nanoseconds. 2. decay rates of particles. decay rates of particles have been precisely measured. the particle is then accelerated to speeds over 99% of the speed of light. the decay rate is significantly slower. explain away. i'm gonna go with einstein on this relativity thing.
Good Zanket, Good. I'm sure we don't agree at this point but at least you show an understanding of my point and are thinking. That is more than I have been able to get others to do. As far as O'Razor, it is a matter of interpretation as to which is more simple. From my understanding of each version Relativity is far more complex but in the final analysis it really doesn't matter which is more complex as long as it is correct because the difference in our physics becomes radically different. Thanks for your response.
Certainly Helloween, Each is free to choose there preferred view, at least until there is unequivicable proof of one over the other. As far as the examples you give, they are not new or unknown and are covered by what appear to be viable alternatives. Many of the features of Relativity, at least observationally and by test data, remain unchanged assuming the alternatives. It is the underlying physics that produces those results that is different and from there the extrapolated signifigance of the theory when applied to untested extremes. To clarify: #1 - Atomic clocks are not magic they are just clocks as any other clock but simply more accurate. The problem is there has not yet been a clock invented that measures time. They all in one process or another are measuring process, not time. Time has never and may never be measured. #2 - Cosmic particles are subject to external forces of deceleration. G force even by Relativity is purported to slow time. But as just mentioned you are looking at a process and that doesn't even prove time exists as a physical component of the Universe. All that has been proven or measured is a change in process. These are far cries from declaring time as a functioning property which can be manipulated or is linked as time, dimension and mass are by Relativity. I am afraid the proof just isn't there to make that determination. I don't really care if Relativity is valid or not, I simply want to know the truth and to see physics advance. Assuming a complex theory which is, as has been stated, counter-intuitive and full of conflicts, is the answer and to stop considering alternatives WOULD BE A HORRIFIC MISTAKE for science.
Re: Certainly NO, NO, and NO! Relativity does not claim that G force slows time. Relativity says that clocks at different gravitational potentials will measure each other as moving at different rates. This is a totally different proposition. If I put two clocks in a uniform G field (where by the G force felt by each clock is exactly the same) with one clock higher in the field than the other: Then, from the lower clock, the higher clock will be measured as running fast, and from the higher clock, the lower clock will be measured as running slow, even though both clocks experience exactly the same g-force.
Correct me if wrong Janus, Technically you are correct but your point I believe is actually mute. That is gravity and acceleration (g's) according to Relativity affects time. My point was meant in a most general way, not as a paper on the intricacies of the subject..
Re: Correct me if wrong Sorry, but you don't get out of it that easily. Your "point" betrayed a complete lack of understanding of the concepts of Relativity even if meant in a "most general way". You said: The problem is that these external forces only affect how things are measured from within the "accelerated" frame. Not how things within the accelerated frame are measured from a non-accelerated frame. Example: put two clocks within an accelerating rocket, one in the tail and one in the nose. Measured from within the rocket, the nose clock will run faster than the tail clock. Measured from the frame that the rocket is accelerating wrt, both clocks will increasingly run slower and slower by the same rate (They will remain synchronized). That rate at any instant is determined by the rocket's relative velocity wrt the frame at that moment. The acceleration of the rocket has no effect other than the change of relative velocity. Ergo, you cannot use the acceleration/deceleration of the particle to explain the particle's increased half-life, because this is realized from a frame outside the accelerated frame.
