Car is different case, we are driving under gravity and drag, so we need more power to get faster. Right? <div class="Discussion_UserSignature"> </div>
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I though an object will have the mass increase only if they accelerate, not at constant velocity. How heavy is a 10tons spacecraft crusing at 0.9c? Or can we say the rest of the surrounding moving at 0.9c relative to the spacecraft, so the surrounding must have their mass added instead? <div class="Discussion_UserSignature"> </div>
Also note that at current rocket thrust technology, the max velocity will be not be any near light speed, because the velocity will not ever exceed thrust velocity which is around 200.000km/h.<br /><br />So, to travel faster, photon thrust, will be more likely to have a good speed, although it has a low thrust force, but it has a thrust speed near the speed of light. In outer space, do not need big thrust, only high velocity thrust, because there is no drag and moving object will keep moving. <div class="Discussion_UserSignature"> </div>
<blockquote><font class="small">In reply to:</font><hr /><p><br />lukman: Also note that at current rocket thrust technology, the max velocity will be not be any near light speed, because the velocity will not ever exceed thrust velocity which is around 200.000km/h.<br /><p><hr /></p></p></blockquote><br /><br />In fact, space craft velocity can exceed (and exceeds) thrust exhaust velocity. For example, the exhaust velocity of shuttle engines are about 4,500 m/s, but the final speed of the shuttle is somewhere between 7,000 - 8,000 m/s (depending on the altitude of the orbit). It's all about the amount of propellat you have.<br /> <div class="Discussion_UserSignature"> <p> </p><p>________________ </p><p>reaaliaika.net </p> </div>
<blockquote><font class="small">In reply to:</font><hr /><p><br />stevehw33: Exhaust velocity is critical to how fast one can accelerate, but not to end point velocity.<br /><p><hr /></p></p></blockquote><br /><br />And more importantly, exhaust velocity is critical to the ship's mass ratio, e.g. how much propellant you need to take with you to reach target velocities. The more mass you can throw away and the faster that mass goes, the more acceleration you get.<br /><br />But in the space (for robots) the more important is the final velocity, since that is needed to get to the trajectories. <div class="Discussion_UserSignature"> <p> </p><p>________________ </p><p>reaaliaika.net </p> </div>
Ok, back to the topic. So most ppl will agree that light speed is constant, so at least for now, forget about FTL, this site wil help to explain:<br /><br />http://www.pbs.org/wgbh/nova/einstein/<br /><br />http://www.pbs.org/wgbh/nova/einstein/kaku.html <div class="Discussion_UserSignature"> </div>
<blockquote><font class="small">In reply to:</font><hr /><p><br />So most ppl will agree that light speed is constant, so at least for now, forget about FTL ...<br /><p><hr /></p></p></blockquote><br /><br />Yes, most physicists agree that light speed is constant and that it's a barrier that cannot be easily broken in physical world.<br /><br />I'm not a physicst and I was shocked when finding out that according to relativity theory not only our spatial dimensions are relative, but also our time is relative; that there is no absolute time in the Universe and thus FTL transfers cause time travel paradoxes. It's all up to the relative speed difference of the observers... That caused all my FTL speculations for my planned scifi book to collapse down to small pieces, because relativity theory has much more empirical observations for backing it up than FTL travels have :-(<br /><br />If there is a way for FTL transfers of information, energy or matter, it's something very very imaginative - something, that "distords" not only the space, but also the time. Luckily we don't know all at the moment 
Douglas Adam's "Infinite Improbability Drive" sounds no more fictional than worm holes, hyperspaces or space-time warpping engines...<br /><br />BTW, what is "ppl"? <br /><br />EDIT: Analogueously (which is a little bit dangerous), I'd been thinking that if all the matter (and energy) here would be made of liquid water, breaking the speed of sound in water (using vehicles made of liquid water) would be nearly impossible job. Now, when we're objects made of space-time, breaking speed of light can be very hard job to do (we need to deal with the time, too). Addition: In this analogue, it's good to remember, that we don't seem to have luminiferous aether in the space-time...<br /> <div class="Discussion_UserSignature"> <p> </p><p>________________ </p><p>reaaliaika.net </p> </div>
Douglas Adam's "Infinite Improbability Drive" sounds no more fictional than worm holes, hyperspaces or space-time warpping engines...<br /><br />BTW, what is "ppl"? <br /><br />EDIT: Analogueously (which is a little bit dangerous), I'd been thinking that if all the matter (and energy) here would be made of liquid water, breaking the speed of sound in water (using vehicles made of liquid water) would be nearly impossible job. Now, when we're objects made of space-time, breaking speed of light can be very hard job to do (we need to deal with the time, too). Addition: In this analogue, it's good to remember, that we don't seem to have luminiferous aether in the space-time...<br /> <div class="Discussion_UserSignature"> <p> </p><p>________________ </p><p>reaaliaika.net </p> </div>pp = people -)<br />Many theory for FTL, most sound nice,but none proven, but we must welcome all possibility. Before Copernicus, we though earth was flat. We also never thought that a 100ton steel can defy gravity. 200 years before there is adjustion in Newton Law. So, we will never know 200 years from now, especially at current rate of technology is developing. <div class="Discussion_UserSignature"> </div>
<blockquote><font class="small">In reply to:</font><hr /><p><br />lukman: pp = people -) <br /><p><hr /></p></p></blockquote><br /><br />Thanks <br /><br /><blockquote><font class="small">In reply to:</font><hr /><p><br />lukman: Many theory for FTL, most sound nice,but none proven, but we must welcome all possibility. Before Copernicus, we though earth was flat. We also never thought that a 100ton steel can defy gravity. 200 years before there is adjustion in Newton Law. So, we will never know 200 years from now, especially at current rate of technology is developing.<p><hr /></p></p></blockquote><br /><br />It is absolutely true that we don't know what we will know 200 years from now - I think we only know, that they haven't invent time travelling or if they did, they didn't want to come here to tell it... That's one argument against FTL in future for scientists (according to current observations, FTL ~ time travels).<br /><br />But I'm still somewhat optimistic. If we don't find ways to go FTL, we certainly find some other interesting & imaginative ways to travel... <div class="Discussion_UserSignature"> <p> </p><p>________________ </p><p>reaaliaika.net </p> </div>
<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p><br />lukman: Many theory for FTL, most sound nice,but none proven, but we must welcome all possibility. Before Copernicus, we though earth was flat. We also never thought that a 100ton steel can defy gravity. 200 years before there is adjustion in Newton Law. So, we will never know 200 years from now, especially at current rate of technology is developing.<p><hr /></p></p></blockquote><br /><br />It is absolutely true that we don't know what we will know 200 years from now - I think we only know, that they haven't invent time travelling or if they did, they didn't want to come here to tell it... That's one argument against FTL in future for scientists (according to current observations, FTL ~ time travels).<br /><br />But I'm still somewhat optimistic. If we don't find ways to go FTL, we certainly find some other interesting & imaginative ways to travel... <div class="Discussion_UserSignature"> <p> </p><p>________________ </p><p>reaaliaika.net </p> </div><blockquote><font class="small">In reply to:</font><hr /><p>Why would it be infinite energy to accelerate mass near the speed of light? <p><hr /></p></p></blockquote> Mass is tantamount to the resistence to being moved, and the faster the acceleration, the more energy is needed to do so. Hence if you push someone, a certain amount of energy is required to do so. This person would be accelerated in the direction of the push. Now if you wanted to accelerate this person a bit faster you might take a running start at them to do so. Don't try this at home. . To move this person to a higher acceleration requires more energy. We can deduce from this that more and more energy is required to accelerate this person at higher and higher rates.<br /><br />This is a contention of mine, so take it with a grain of salt. The resistence to acceleration is the result of self interaction. hence when you throw a ball, it resist the acceleration by self interaction. <br /><br />How? <br /><br />All localized entities like particles and such propogate gravitational waves. These gravitational waves propogate outward at C, as such like what you might see in a spiral pattern. The gravitational wave is also for all intensive purposes, the particle itself. Now should you push this particle in a direction, there will be a self interaction. i.e. The particale interacts with it's own gravitational field. A faster acceleration constitutes a greater self interaction. Same process here as pushing someone, more and more energy is required for higher rates of acceleration.<br /><br />Now lets go in space and send a ship to the speed of light. Lets fire up the engines and accelerate the ship at say 1g for twenty minutes. There will be a constant resistance to acceleration through this self interaction as described, as long as we put enough energy into the ship to maintain the 1g acceleration at all times. Lets turn the engines off for a minute. You will coast at that speed with no slow down. The self interaction s
. To move this person to a higher acceleration requires more energy. We can deduce from this that more and more energy is required to accelerate this person at higher and higher rates.<br /><br />This is a contention of mine, so take it with a grain of salt. The resistence to acceleration is the result of self interaction. hence when you throw a ball, it resist the acceleration by self interaction. <br /><br />How? <br /><br />All localized entities like particles and such propogate gravitational waves. These gravitational waves propogate outward at C, as such like what you might see in a spiral pattern. The gravitational wave is also for all intensive purposes, the particle itself. Now should you push this particle in a direction, there will be a self interaction. i.e. The particale interacts with it's own gravitational field. A faster acceleration constitutes a greater self interaction. Same process here as pushing someone, more and more energy is required for higher rates of acceleration.<br /><br />Now lets go in space and send a ship to the speed of light. Lets fire up the engines and accelerate the ship at say 1g for twenty minutes. There will be a constant resistance to acceleration through this self interaction as described, as long as we put enough energy into the ship to maintain the 1g acceleration at all times. Lets turn the engines off for a minute. You will coast at that speed with no slow down. The self interaction sMay be travelling back in time will offend time travel prime directive. Just like if we say there is no intelligent outside human being because we never seen any or visited by them. Maybe the space is to vast, so is the time is so vast that they have no interest travelling back before year 3000 for example, or maybe if they indeed travelling back in time they open another parallel dimension. That our current dimension is a pure origin dimension, (serial movies Slider having hard time to return to their own dimension) so that they will never reach our time space.... Many reasons for that, although i dont really believe in time travel, but maybe, who knows.<br />BTW, how did you do those highlight with lines on top an bottom? <div class="Discussion_UserSignature"> </div>
you may find this site interesing <br /><br />http://www.pbs.org/wgbh/nova/time/timespeak.html<br /><br />http://www.pbs.org/wgbh/nova/time/through2.html <div class="Discussion_UserSignature"> </div>
Very comphrehensive, agree most of the point. For me, the reason that we cant execeed speed of light because:<br />1. speed of light is constant<br />2. Time dilation is huge as you are closer to light speed.<br />3. Mass increases in moving object. (only acceleration increases mass under normal newton law and daily physics)<br /><br />Although i dont know the reasons for all above -P<br /> <div class="Discussion_UserSignature"> </div>
<blockquote><font class="small">In reply to:</font><hr /><p><br />lukman: Many reasons for that, although i dont really believe in time travel, but maybe, who knows.<br /><p><hr /></p></p></blockquote><br /><br />I'm currently designing a scifi book and I'm finding out how to design a "believable" FTL transfers. I don't believe in time travels, too, but future FTL may involve some effects similar to time travels - we just don't know yet, which kind (and which kind of laws restrict the transfers). And certainly we don't know all of the Universe and time-space right now, so there may be some very fascinating surprises encountered in the future.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p><br />lukman: BTW, how did you do those highlight with lines on top an bottom?<br /><p><hr /></p></p></blockquote><br /><br />These bulletin board systems regularly implement quote -tag. So put "quote" in brackets to start and "/quote" in brackets to stop. <div class="Discussion_UserSignature"> <p> </p><p>________________ </p><p>reaaliaika.net </p> </div>
Einstein's relativity is about observers. The space craft may be traveling 0.9 c with respect to Earth, but the crew is approximately zero speed with respect to their space craft. The average speed with respect to near by sub-atomic particles could be 0.88c or 0.999 c. We could find a distant star trasveling approximately the same speed and direction. Observers near that star would observe no time shortening nor mass increase. It's all relative. The space craft can accelerate at 1 g for another year, even though that results in faster than c by Newton's math and we can still find a distant star traveling about the same speed and direction as the space craft. Neil
My personal dilemma is reconciling recessional velocity (red shifted galaxies) with Relativity.<br /><br />A galaxy is certainly not massless. Yet we can measure the rate at which they recede from us and find significant velocities that just shouldn't be possible.<br /><br />In effect, myself and everyone reading these fora are receding from something at <b>c</b> right now if our red shift observations are what they appear to be.<br /><br />The only conclusion I can draw is that traveling FTL <b>is</b> possible, but that it's an inaccurate way to articulate what's really happening.<br /><br />I have no doubt that in our 4 dimensional space-time, using known forces and formulas available to us that we cannot travel faster than light. I'm certain we cannot.<br /><br />But there's an 800 pound gorilla in the room that refuses to go away.<br /><br />The FTL issue is obviously outside the framework that people try to apply in their "FTL theories".<br /><br />That's the attraction of extra dimensions and/or hyperspace. It gives us an explanation of how we might circumvent the speed limit without "breaking" it.<br /><br />I wish I would have been born a few hundred years from now.<br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>
A lot of people explain the observation that distant galaxies may be receding from us at the speed of light or even faster, by saying that although we cannot accelerate mass to the speed of light according to Einstiens theories, there is nothing in those theories that precludes the idea that space can expand faster than light. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>
<blockquote><font class="small">In reply to:</font><hr /><p> I'm currently designing a scifi book and I'm finding out how to design a "believable" FTL transfers. I don't believe in time travels, too, but future FTL may involve some effects similar to time travels - we just don't know yet, which kind (and which kind of laws restrict the transfers). And certainly we don't know all of the Universe and time-space right now, so there may be some very fascinating surprises encountered in the future. <p><hr /></p></p></blockquote><br /><br />Thank you and good luck designing your scifi book. <img src="/images/icons/cool.gif" /> <div class="Discussion_UserSignature"> </div>
Einstein's thory of relativity is about observers. If the space craft is going 0.9 c with respect to Earth; the crew is moving approximately zero speed with respect to the space craft, so the crew observes no increase in mass, shortening of time nor shortening of length. Many sifi stories are wrong. A search will find a distant star that is moving about the same speed and direction as the space craft. Observers near that star will observe no space craft mass increase, nor changes in time nor length.<br />With sufficient fuel, the space craft can accellerate at 1 g for another year, resulting in much faster than light speed by Newton math. We can still find a distant star moving about the same speed and direction as the space craft. All is relative. Absolutes are rare. Neil
If I understand it correctly special relativity states that time dilation and length contraction are symetrical between observers <i> in an inertial frame of reference. </i><br /><br />Concentrating on time dilation and the twins paradox, the reason for the different aging between the twin observing back home and the twin who travelled at 0.9c is that, regardless of the two twins <i> relative </i> speed, one twin has remained in an interial frame of reference for the whole journey (he stayed on Earth, which moves through space by inertia), but the other twin, on the spaceship, was <i> not </i> in an inertial frame for the whole time they were accelerating and decelerating.<br /><br />You said the crew observes no increase in mass. The way I understand it this is partially incorrect, for they would see indirectly how much extra mass they had when they saw how much fuel they need to accelerate that mass any faster. The crew does also observe length contraction. They observe the distance to their destination decrease through the blueshift of its light, which is confirmed when they travel that distance in far less time than the observer on Earth sees them take.<br /><br />As described by the Lorentz Transformation in Special Relativity, for a 2 light year journey, at 0.866c the journey takes them 1 year. Morever, at that speed they see the distance to their destination shrink to 0.866 of a light year. But observers on Earth see them take 2.3 years to make the journey.<br /><br />So the crew can indirectly notice length contraction to their destination and mass increase due to increase in fuel use. The cannot directly see their own bodymass or shipmass increase of course, nor do they know that seconds are ticking slower for them than they are back on Earth (but they will find out when they get back!).<br /><br />As for the idea that with sufficient fuel the spacecraft can accelerate at 1g until they are travelling at lightspeed or more, it seems mathematically true. But when we do <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>
Wow...I havn't been on here in a long time, lol seems like my posts eventually do get somewhere =p <br /><br />Thanks everyone for your replys, they've helped alot!!
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