# Light propulsion engine.

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#### freeshark

##### Guest
Hey everyone, <br /><br />I have been thinking of ways to aquire massive amounts of speed over a long period of time. No need to go super fast right from the get go. So what if it takes 2 weeks to reach 100,000,000 miles an hour so long as you get to that speed?<br /><br />1. Theoretically, How fast could a ship go in space? Forget about what pushes it. I just want to know know how fast it could go in space if nothing got in it's way. <br /><br />2. Assuming there was NOTHING but space in front or around a man made space ship. Would the Ship feel any kind of stress from MASSIVE amounts of speed?<br /><br />3.Can Sound or strong vibrations have any effect in Space? <br /><br />The reasons for these precise questions:<br /><br />The way I understand space so far is that if you could "push" an object (Say a pencil) to go about 1 MPH, the pencil would NEVER slow down or stop unless it was affected by some thing on the way. <br /><br />If you push the pencil AGAIN with EXACTLY the same force as you did the first time (As the pencil is still moving) the pencil will go 1 MPH faster and so on. So if you pushed the pencil 10,000,000 times the pencilshould travel at a speed of 10,000,000 MPH. <br /><br />Is that correct?<br /><br />Because if it is we only need to figure out a way to make a reaction in space based on Energy rather then chemicals that will "Push" an object.<br /><br />Even if the "Push" in question was very small, eventually you would be able to aggregate an emormous amount of speed. <br /><br />Then all we have to figure out would be how to protect the ship from on coming objects. I have a few thoughts on that as well.<br /><br />Any one?

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#### nacnud

##### Guest
<font color="yellow">Hey everyone, <br /><br /><font color="white">’lo welcome <img src="/images/icons/smile.gif" /><br /><br /><font color="yellow">I have been thinking of ways to acquire massive amounts of speed over a long period of time. No need to go super fast right from the get go. So what if it takes 2 weeks to reach 100,000,000 miles an hour so long as you get to that speed? <br /><br />1. Theoretically, How fast could a ship go in space? Forget about what pushes it. I just want to know how fast it could go in space if nothing got in it's way. <br /><br /><font color="white">3x10<sup>8</sup>m/s, the speed of light<br /><br /><font color="yellow">2. Assuming there was NOTHING but space in front or around a man made space ship. Would the Ship feel any kind of stress from MASSIVE amounts of speed? <br /><br /><font color="white">If there was nothing but space then no, but space isn’t completely empty<br /><br /><font color="yellow">3.Can Sound or strong vibrations have any effect in Space? <br /><br /><font color="white">The standard answer is no, ‘sound’ can propagate though the solar wind, sort of , but you’re ignoring that and saying space is empty there is not sound. There is sound in space in the same way the Moon has an atmosphere. (old SCD joke)<br /><br /><font color="yellow">The reasons for these precise questions: <br /><br />The way I understand space so far is that if you could "push" an object (Say a pencil) to go about 1 MPH, the pencil would NEVER slow down or stop unless it was affected by some thing on the way. <br /><br />If you push the pencil AGAIN with EXACTLY the same force as you did the first time (As the pencil is still moving) the pencil will go 1 MPH faster and so on. So if you pushed the pencil 10,000,000 times the pencil should travel at a speed of 10,000,000 MPH. <br /><br />Is that correct? <br /><br /><font color="white">No, relativity will kick in a some point, the maximum speed you can get to is the speed of light.<br /><br /><font color="yellow">Because if it is we only need</font></font></font></font></font></font></font></font></font></font></font>

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#### freeshark

##### Guest
Hey Duncan,<br /><br />Than you so much for the reply! Very helpful. I am glad I am not completely wrong on some points.<br /><br />3.Can Sound or strong vibrations have any effect in Space? <br /><br />The standard answer is no, ‘sound’ can propagate though the solar wind, sort of , but you’re ignoring that and saying space is empty there is not sound. There is sound in space in the same way the Moon has an atmosphere. (old SCD joke) <br /><br />What I meant by this is Can I create sound in space and if I do can the vibrations (assuming they were strong enough) push an object?<br /><br />However, I think you answered my question with the light propulsion theory. That is EXACTLY what I was looking for. Has it evr been tested?<br /><br />I only want to propell the ship once in space. Even if it is unpracticle it would be great to have propulsion with out fuel.<br /><br /><br /><br />

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#### nacnud

##### Guest
Sound is the vibrations in the air, in space there is no air so there is no sound.<br /><br />The light propultion idea is impractical because the thrust generated is very very small. <br /><br /><font color="yellow">Even if it is unpracticle it would be great to have propulsion with out fuel. <br /><br /><font color="white">The thing is you are useing a fuel for the light drive, you use energy to creat the light in the first place.</font></font>

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#### mlorrey

##### Guest
Well, there is hope for field effects, though trying to grab onto space-time is a slippery proposition.

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#### nacnud

##### Guest
Oh yeah I forgot about electrodynamic tethers, check these out, could be useful if you find yourself in orbit around planet a magnetic feild ie Earth, Jupiter etc.

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#### nexium

##### Guest
Reaching 100,000,000 miles per hour in 2 weeks is rapid acceleration. If you accelerate at 20 feet per second per second for 5 million seconds, your speed is 100,000,000 feet per second which is about 70,000,000 miles per hour. That acceleration produces about 60% of Earth's gravity, which is likely healthy for the crew. 5 million seconds is 1389 hours = 58 days = almost 2 months.<br />The stuff in the way is usually trivial at lower speeds, but your craft will collide with more sub atomic particles at a 100 million miles per hour, and the radiation produced by collisions is a danger to the crew. Likely you can go somewhat faster before the radiation problem is beyond present shielding, such as several feet of lead, but the shielding mass will require lots of fuel to accelerate. 2 The ship would not feel any stress even at 900 million miles per hour, which is about 98% of the speed of light, but it is not realistic to think nothing is in front of the ship. 3 Sound and vibration caused by colliding with sub atomic particles would be loud. A pea size impactor would pass though the ship even with feet of steel in the way at 100 million miles per hour. Larger than pea size impactors can possibly be dodged, if we have a dozen radar sets flying about a million miles ahead of the space craft. This gives about 3.6 seconds to make the dodge maneuver. A dozen concentric foil shields traveling ahead of the space craft may convert smaller than pea size impactors (including sub atomic particles) to gamma rays. Neil

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#### nexium

##### Guest
The Bassard ram jet assumes that the sub atomic particles can be directed into a fusion chamber, by an extremely large and powerful magnetic field which uses super conductors even at 100 million miles per hour. Bassard's ideas are mostly untested. Neil

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#### nexium

##### Guest
Reaching 100,000,000 miles per hour in 2 weeks is rapid acceleration. If you accelerate at 0.2 feet per second per second for 5 million seconds, your speed is 1,000,000 feet per second which is about 700,000 miles per hour. That acceleration produces about 0.6% of Earth's gravity, which is likely is worse than free fall for the health of the crew. 5 million seconds is 1389 hours = 58 days = almost 2 months.<br />0.2g is about the best we can expect from the next generation of ion engines.<br />The stuff in the way is usually trivial at lower speeds, but your craft will collide with slightly more sub atomic particles at a one million miles per hour, and the radiation produced by collisions is a danger to the crew. Likely you can go much faster before the radiation problem is beyond present shielding, such as several iches of lead, but the shielding mass will require lots of fuel to accelerate. Neil

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#### nexium

##### Guest
Reaching 100,000,000 miles per hour in 2 weeks is rapid acceleration. If you accelerate at 2 feet per second per second for 50 million seconds, your speed is 100,000,000 feet per second which is about 70,000,000 miles per hour. That acceleration produces about 6% of Earth's gravity, which may be a nuisance for the crew, with no health benefit. 50 million seconds is 13890 hours = 580 days = almost 1.6 years. <br />The stuff in the way is usually trivial at lower speeds, but your craft will collide with more sub atomic particles at a 100 million miles per hour, and the radiation produced by collisions is a danger to the crew. Likely you can go somewhat faster before the radiation problem is beyond present shielding, such as several feet of lead, but the shielding mass will require lots of fuel to accelerate. <br />Neil

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#### kelvinzero

##### Guest
There is also the concept of hitting the craft with particle beams instead of light beams. These could carry more momentum than light but still be moving at a healthy fraction of light speed.<br /><br />The big problem with beamed power is spreading of the beam, even over comparatively short distances.<br /><br />Whatever you use though, you always have the problem that kinetic energy is the square of the velocity, even in basic neutonian mechanics. What this means in terms of the particle beam is that it will become less effective the faster the craft is retreating from it, but the same problem occurs regardless of the method, including carrying the propellent with you.<br />

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#### lukman

##### Guest
<blockquote><font class="small">In reply to:</font><hr /><p><br />No, relativity will kick in a some point, the maximum speed you can get to is the speed of light. <p><hr /></p></p></blockquote><br /><br />Do you or anyone know at what speed? <div class="Discussion_UserSignature"> </div>

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#### qso1

##### Guest
The speed of light itself is 670,615,000 mph or 186,282 fps. Check out the Lorentz transformation at this link:<br /><br />http://en.wikipedia.org/wiki/Special_relativity<br /><br />It appears the practical answer to your question based on current knowledge is 75-80% SOL being the maximum we can attain. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

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#### MeteorWayne

##### Guest
Typo alert:<br />that's 186,282 miles per second, not fps <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

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#### lukman

##### Guest
Thanks for the information bro -) <div class="Discussion_UserSignature"> </div>

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