Derek Willis Posted April 13, 2016 #26 Share Posted April 13, 2016 no that is physics. you travel at the speed of light your clock slowly advances. the clock on the planet quickly advances. this was measured on the moon flights. star trek gets around this with the warp field. star wars just ignores it. Firstly, regardless of what velocity you travel at, as far as you are concerned your clock doesn't change. People who are not travelling with you will see your clock slow down. And you will see their clocks slow down. That is what relativity is all about. Secondly, if a probe travels to Alpha Centauri in 30 years its velocity would be about 15% of the speed of light. Relativistic effects don't really kick in at that speed so only a small difference in the rates that clocks move would be observed. Link to comment Share on other sites More sharing options...
Derek Willis Posted April 13, 2016 #27 Share Posted April 13, 2016 There is also the question of generating the power to run the transmitter on the spacecraft. The Voyager spacecrafts had 3 RTG's, ech weighing 37,7 kg (113,1 kg total). https://en.wikipedia.org/wiki/MHW-RTG Solar cells won't work in interstellar space and nuclear power has lower limits to its size, so I don't see how you could power a radio transmitter with a power supply that only weighs a few grams ? One thought I had is that the solar sail used to accelerate the craft with the laser could double as a solar panel and generate electricity when it reaches Alpha Centauri. But I still believe it is physically impossible to do this and build a transmitter in a craft that weights just a few grams. There must be something an idiot like me is missing if Prof. Hawking believes it is possible! 1 Link to comment Share on other sites More sharing options...
+Noteverythingisaconspiracy Posted April 13, 2016 #28 Share Posted April 13, 2016 One thought I had is that the solar sail used to accelerate the craft with the laser could double as a solar panel and generate electricity when it reaches Alpha Centauri. But I still believe it is physically impossible to do this and build a transmitter in a craft that weights just a few grams. There must be something an idiot like me is missing if Prof. Hawking believes it is possible! A laser that could power a spacecraft near Alpha Centauri would have to be huge. Its that bloody inverse square law again !* So I guess you can count me as one of the idiots too. *) Plus the fact that there is no way that a laser will remain focused at such a huge distance, meaning that the laser would have to be even bigger to begin with. 1 Link to comment Share on other sites More sharing options...
NCC1701 Posted April 13, 2016 #29 Share Posted April 13, 2016 Even if it can be done how would you brake when you approach your target? The laser can only accelerate it. Link to comment Share on other sites More sharing options...
Derek Willis Posted April 13, 2016 #30 Share Posted April 13, 2016 Even if it can be done how would you brake when you approach your target? The laser can only accelerate it. Presumably the probe would be on a "fly-by" mission rather like when New Horizons flew past Pluto last year. Link to comment Share on other sites More sharing options...
Astra. Posted April 13, 2016 #31 Share Posted April 13, 2016 I know no-one can say for sure, but is there much danger of hitting "something" travelling that distance ? Would a few molecules be enough to kill it ? It seems they have already considered that problem. the satellite must be protected from particles while it’s in transit to Alpha Centauri—at one fifth the speed of light, even a mote of dust can be catastrophic. (article below).. Even if it can be done how would you brake when you approach your target? The laser can only accelerate It wont be breaking. And if the StarChip survives to the triple star system, it will have about two hours to snap pictures—because the plan does not include breaks—using a camera of roughly two megapixel resolution. http://www.wired.com...lites-much-ask/ 1 Link to comment Share on other sites More sharing options...
Merc14 Posted April 13, 2016 #32 Share Posted April 13, 2016 (edited) I would kindly disagree in most cases. To become a billionaire one must follow the conventional rules that earn money. There may be innovation involved, but this innovation is still aimed at profit. I think more good could be done if the 1% would consider unconventional projects without $$$ profit for themselves as the main goal. That Russian billionaire who spent 400 million $ on his yacht was a drop in the bucket for him, and he didn't miss that money he spent. I would think 400 million could have been used more usefully to aid humanity in some way. How about all the thousands of people employed because these people buy those yachts? How about how they push ship-building technology with these innovative designs? I remember when we "punished the rich" with a luxury tax and killed the boat building industry in the US. The unintended consequences of these irrational reactions aren't usually well thought out. A laser that could power a spacecraft near Alpha Centauri would have to be huge. Its that bloody inverse square law again !* So I guess you can count me as one of the idiots too.*) Plus the fact that there is no way that a laser will remain focused at such a huge distance, meaning that the laser would have to be even bigger to begin with. I think they'd lase it for as long as possible and then the thing would be on its own at whatever velocity it had attained. Even if it can be done how would you brake when you approach your target? The laser can only accelerate it. I am assuming a flyby mission like New Horizons which will continue on forever. Edited April 13, 2016 by Merc14 1 Link to comment Share on other sites More sharing options...
Derek Willis Posted April 13, 2016 #33 Share Posted April 13, 2016 How about all the thousands of people employed because these people buy those yachts? How about how they push ship-building technology with these innovative designs? I remember when we "punished the rich" with a luxury tax and killed the boat building industry in the US. The unintended consequences of these irrational reactions aren't usually well thought out. I know this is off-topic but a similar thing happened in the UK in the 1970's. For over a century some of the best cruise ships in the world were made in UK shipyards. But when wealthy people were taxed to the hilt (97.5% in some cases) the demand for top-end cruises fell off. Result: Hundreds of shipyard workers lost their jobs and cruise ships aren't made in the UK anymore. Stupid economics, IMO. 1 Link to comment Share on other sites More sharing options...
TheGreatBeliever Posted April 13, 2016 #34 Share Posted April 13, 2016 They always say that but it actually comes out in four or five decades! Link to comment Share on other sites More sharing options...
+Noteverythingisaconspiracy Posted April 13, 2016 #35 Share Posted April 13, 2016 I think they'd lase it for as long as possible and then the thing would be on its own at whatever velocity it had attained. My post was about how they could possibly use the laser to power the spacecraft. I just don't see a realistic way of doing that in the size constraint that they have. Another limiting factor would be the sensors to be carried. Is it possible to build a camera that small ? I am certainly no expert, but I was under the impression that you need a large lens if you wan't to take detailed images ? Don't get me wrong, I don't think that the idea of using a laser pushed sail is bad. in fact it is one of the most realistic ways of achieving interstellar travel. I just don't believe that it is physically possible to design a usefull spacecraft as small as they claim. 1 Link to comment Share on other sites More sharing options...
danielost Posted April 13, 2016 #36 Share Posted April 13, 2016 My post was about how they could possibly use the laser to power the spacecraft. I just don't see a realistic way of doing that in the size constraint that they have. Another limiting factor would be the sensors to be carried. Is it possible to build a camera that small ? I am certainly no expert, but I was under the impression that you need a large lens if you wan't to take detailed images ? Don't get me wrong, I don't think that the idea of using a laser pushed sail is bad. in fact it is one of the most realistic ways of achieving interstellar travel. I just don't believe that it is physically possible to design a usefull spacecraft as small as they claim. the laser their talking about is strong enough to take out orbiting sats. Link to comment Share on other sites More sharing options...
crandles57 Posted April 13, 2016 #37 Share Posted April 13, 2016 the laser their talking about is strong enough to take out orbiting sats. Is that a problem? Just locate the laser at Sun Earth L1 Lagrange point or on moon or a very high orbit or... Presumably you don't want atmosphere interfering with focussing and reducing power of laser anyway. Link to comment Share on other sites More sharing options...
psyche101 Posted April 14, 2016 #38 Share Posted April 14, 2016 Lockheed Martin's Ben Rich would be laughing his *ss off I mean 30 years, yeah, but in the FUTURE? What does he have to laugh about, and not be amazed at? 1 Link to comment Share on other sites More sharing options...
+DieChecker Posted April 14, 2016 #39 Share Posted April 14, 2016 Don't get me wrong, I don't think that the idea of using a laser pushed sail is bad. in fact it is one of the most realistic ways of achieving interstellar travel. I just don't believe that it is physically possible to design a usefull spacecraft as small as they claim. Considering that most technology goes to about 10% what it was every 2 to 10 years, I think they'll find a way. Computer processor components today are about a thousand times smaller then when I joined Intel 11 years ago. I know this is off-topic but a similar thing happened in the UK in the 1970's. For over a century some of the best cruise ships in the world were made in UK shipyards. But when wealthy people were taxed to the hilt (97.5% in some cases) the demand for top-end cruises fell off. Result: Hundreds of shipyard workers lost their jobs and cruise ships aren't made in the UK anymore. Stupid economics, IMO. Probably more like tens of thousands lost jobs. 1 Link to comment Share on other sites More sharing options...
+DieChecker Posted April 14, 2016 #40 Share Posted April 14, 2016 It wont be breaking. http://www.wired.com...lites-much-ask/ Why, oh why, are they so many Read-Fails? People read the title of an article, leap to assumptions and start going off, when if they'd just read the article, they'd have their questions answered. 2 Link to comment Share on other sites More sharing options...
psyche101 Posted April 14, 2016 #41 Share Posted April 14, 2016 Are they betting on emerging technologies? Link to comment Share on other sites More sharing options...
+DieChecker Posted April 14, 2016 #42 Share Posted April 14, 2016 Are they betting on emerging technologies? From what I read about it, 100% they are. To make the lasers and to micronize the components. I'd imagine sending a signal back to Earth from 5 light years starting at 20% the speed of light might take some figuring out too. I wonder what the visual resolution at 20% speed of light would be? 1 Link to comment Share on other sites More sharing options...
Habitat Posted April 14, 2016 #43 Share Posted April 14, 2016 I wonder what the visual resolution at 20% speed of light would be? What are you referring to there ? Link to comment Share on other sites More sharing options...
+DieChecker Posted April 14, 2016 #44 Share Posted April 14, 2016 (edited) What are you referring to there ? I wonder if other then red shift, if the image would be harder to take at high resolution then it would be at less relativistic speeds? Obviously New Horizons took great pics of Pluto when it flew by at about 60,000 kph, but what would the resolution of those pics have been if it was traveling at 18,000 times faster (Light travels at approximately 1080000000 kph). And if that would really affect ultra long range pics, like New Horizons did looking back from Pluto. Edited April 14, 2016 by DieChecker 1 Link to comment Share on other sites More sharing options...
Habitat Posted April 14, 2016 #45 Share Posted April 14, 2016 (edited) I wonder if other then red shift, if the image would be harder to take at high resolution then it would be at less relativistic speeds? Obviously New Horizons took great pics of Pluto when it flew by at about 60,000 kph, but what would the resolution of those pics have been if it was traveling at 18,000 times faster (Light travels at approximately 1080000000 kph). And if that would really affect ultra long range pics, like New Horizons did looking back from Pluto. Beyond my ken, but seems like an extraordinarily difficult exercise in very many ways, for potentially what ? It may well be by the time this idea becomes realistic, technology advances for remote sensing may have rendered it less attractive. After all, it doesn't seem a long time since the first exoplanet was confirmed. Edited April 14, 2016 by Habitat 1 Link to comment Share on other sites More sharing options...
Derek Willis Posted April 14, 2016 #46 Share Posted April 14, 2016 I might have gotten my maths wrong here, but accelerating a probe weighing one gram to 20% of the speed of light requires roughly the same amount as energy as was required to send an Apollo spacecraft to the Moon. That gives some idea of how difficult it will be to send humans to the stars. 1 Link to comment Share on other sites More sharing options...
Derek Willis Posted April 14, 2016 #47 Share Posted April 14, 2016 My post was about how they could possibly use the laser to power the spacecraft. I just don't see a realistic way of doing that in the size constraint that they have. Another limiting factor would be the sensors to be carried. Is it possible to build a camera that small ? I am certainly no expert, but I was under the impression that you need a large lens if you wan't to take detailed images ? Don't get me wrong, I don't think that the idea of using a laser pushed sail is bad. in fact it is one of the most realistic ways of achieving interstellar travel. I just don't believe that it is physically possible to design a usefull spacecraft as small as they claim. Another problem would be the strength of the sail. If the laser acceleration occurs only whilst the probe is in the vicinity of Earth, to reach 20% of the speed of light the acceleration would be massive and that would require a very strong sail. If the acceleration is carried out way into interstellar space to reduce the acceleration, the laser (as you mentioned) would no longer be focused (even at the distance of the Moon a laser beam spreads out to cover hundreds of square meters). I just can't see how any of this could work in a probe weighing no more than a gram. Link to comment Share on other sites More sharing options...
danielost Posted April 14, 2016 #48 Share Posted April 14, 2016 I might have gotten my maths wrong here, but accelerating a probe weighing one gram to 20% of the speed of light requires roughly the same amount as energy as was required to send an Apollo spacecraft to the Moon. That gives some idea of how difficult it will be to send humans to the stars. I don't think humans could survive the same acceleration as the probe. besides they couldn't get back. Link to comment Share on other sites More sharing options...
danielost Posted April 14, 2016 #49 Share Posted April 14, 2016 Another problem would be the strength of the sail. If the laser acceleration occurs only whilst the probe is in the vicinity of Earth, to reach 20% of the speed of light the acceleration would be massive and that would require a very strong sail. If the acceleration is carried out way into interstellar space to reduce the acceleration, the laser (as you mentioned) would no longer be focused (even at the distance of the Moon a laser beam spreads out to cover hundreds of square meters). I just can't see how any of this could work in a probe weighing no more than a gram. instant acceleration. from o to 20% light in 0 seconds. Link to comment Share on other sites More sharing options...
toast Posted April 14, 2016 #50 Share Posted April 14, 2016 instant acceleration. from o to 20% light in 0 seconds. Thats nonsense. Link to comment Share on other sites More sharing options...
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