[The Transhumanist]

Moontanman said:

Friction with the air is what slows down a missile,

That and it's weight pulling it down.

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once in space an object free of the earths gravity or the suns gravity will continue to move until it is acted on by another force.

It won't be free of it's own mass though. Only particles are free of their own mass.

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No matter how massive it is. Speed only increases mass or weight when you are close to the speed of light.

Correction, mass decreases the speed of an object as it approaches the speed of light.

[Moontanman]

Gardamorg are you trying to be a troll? I was trying my best to help you, being a troll is not nice

[The Transhumanist]

Moontanman said:

Gardamorg are you trying to be a troll? I was trying my best to help you, being a troll is not nice

When did I troll?

[Moontanman]

Gardamorg said:

When did I troll?

By claiming things to be true when you know they are patently false. I've read enough of your threads to know you have been shown that objects get more massive not less massive as they get near the speed of light, I know you know an object does not slow down by its self, I know you know an object's mass doesn't have anything to do with it's ability to keep moving when in free fall. I know you know a magnetic field doesn't affect neutral particles. I gave you link to Newtons Laws but you ignored it. If you don't want me to point out your mistakes then just say so and I'll not post in this thread anymore.

[The Transhumanist]

Moontanman said:

By claiming things to be true when you know they are patently false. I've read enough of your threads to know you have been shown that objects get more massive not less massive as they get near the speed of light,

Which is what my whole argument is about, it gets so massive that it's speed decreases because it's thrust can't push it anymore.

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I think you know an object does not slow down by its self, I think you know an object's mass doesn't have anything to do with it's ability to keep moving when in free fall.

Corrected.

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I know you know a magnetic field doesn't affect neutral particles. I gave you link to Newtons Laws but you ignored it. If you don't want me to point out your mistakes then just say so and I'll not post in this thread anymore.

If you think you know all this about me, your gravely mistaken.

I've ALWAYS known an object's mass increases as it moves faster, which is why an object is constantly trying to stay still.

[Moontanman]

Gardamorg said:

Which is what my whole argument is about, it gets so massive that it's speed decreases because it's thrust can't push it anymore.

This is only true very near the speed of light and it doesn't make the object slow down just makes it harder to go faster.

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Corrected.

Thank you

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If you think you know all this about me, your gravely mistaken.

I've ALWAYS known an object's mass increases as it moves faster, which is why an object is constantly trying to stay still.

No, an objects mass only increases very near the speed of light, at much slower speeds this is not true and even close to the speed of light an object is only difficult to accelerate , it does not naturally slow down. Even an object very close to the speed of light will continue on at that speed until an outside force acts on it. In theory it could coast at 99.999999999% of the speed of light forever.

[CraigD]

My vote is for beam-powered propulsion.

There are many possible versions of this approach. My favorite is the Robert Forward type laser-pushed lightsail, but others may well prove more feasible, including the charged particle-pushed magnetic sail Moontanman voted for. Other versions (not mentioned in the wikipedia article, but described in various other sources), commonly referred to as “fountains”, transfer momentum via bullet-like, uncharged, non-light particles.

All of these approaches, with the exception of very low-mass vehicles like Forward’s Starwisp, require the construction and operation of solar-system space based solar energy and beam generating facilities not only many times more massive than the vehicle they propel, but many times more massive than all of the vehicles launched into space in the history of mankind. Such large, in depth programs are, IMHO, the best long-term approaches to spaceflight.

PS: Gardamorg, Moontanman’s efforts to instruct you in the fundamental laws of motion are correct. I fear you’ve gotten too much of your thinking about spaceflight from popular science fiction, such as Star Trek, Star Wars, and Battlestar Galactica, in which spacecraft are depicted as behaving similarly to water surface ships, which make no headway when not under power. Real spacecraft, including all those launched to date, such as the Voyager spacecraft, the most distant manmade objects to date, are powered only briefly, when lifted from Earth, making course corrections, and inserting into orbit around, or landing, or impact with their target bodies.

[The Transhumanist]

CraigD said:

My vote is for beam-powered propulsion.

There are many possible versions of this approach. My favorite is the Robert Forward type laser-pushed lightsail, but others may well prove more feasible, including the charged particle-pushed magnetic sail Moontanman voted for. Other versions (not mentioned in the wikipedia article, but described in various other sources), commonly referred to as “fountains”, transfer momentum via bullet-like, uncharged, non-light particles.

All of these approaches, with the exception of very low-mass vehicles like Forward’s Starwisp, require the construction and operation of solar-system space based solar energy and beam generating facilities not only many times more massive than the vehicle they propel, but many times more massive than all of the vehicles launched into space in the history of mankind. Such large, in depth programs are, IMHO, the best long-term approaches to spaceflight.

PS: Gardamorg, Moontanman’s efforts to instruct you in the fundamental laws of motion are correct. I fear you’ve gotten too much of your thinking about spaceflight from popular science fiction, such as Star Trek, Star Wars, and Battlestar Galactica, in which spacecraft are depicted as behaving similarly to water surface ships, which make no headway when not under power. Real spacecraft, including all those launched to date, such as the Voyager spacecraft, the most distant manmade objects to date, are powered only briefly, when lifted from Earth, making course corrections, and inserting into orbit around, or landing, or impact with their target bodies.

Oh...

[CraigD]

Moontanman said:

No, an objects mass only increases very near the speed of light, at much slower speeds this is not true and even close to the speed of light an object is only difficult to accelerate , it does not naturally slow down.

This is nearly, but not exactly correct. Bodies traveling even at very low speeds relative to an observer. For example, a 100 kg man walking at a typical speed of 1 m/s actually masses

That is, he gains about 625 nanograms - about the mass of a single human egg cell, or a small grain of sand.

Moontanman said:

Even an object very close to the speed of light will continue on at that speed until an outside force acts on it. In theory it could coast at 99.999999999% of the speed of light forever.

This is true only if the object is traveling in a perfect vacuum.

Interstellar space contains has a density of about 1 hydrogen atom per 1 to 10 cubic centimeters, or about to From this, you can calculate the power per unit area of friction for a spacecraft traveling in it as
.
Calculating this for the lower density for craft traveling at 0.1 c (As Janus did in post #32 of “Quickest way to get to The Super Earth”) gives a small, but troubling from a practical engineering perspective, . Calculating it for 0.99999999999 c gives about 500 million!

To put this into some kind of perspective, if the spacecraft used a plug of water ice near absolute zero as frontal shielding, this shield would be vaporized at a rate of about 3.2 meters of thickness per second!

In terms of conservation of momentum, ignoring the practical engineering problem of shielding and cooling, the density of interstellar space would produce an acceleration of

Even for a tiny spacecraft massing only 1000 kg with an frontal area of , traveling 0.99999999999 c, this calculates to about . In about 1 year, it would slow by about 3 m/s, to a speed of about .99999999 c. Friction would never completely stop it relative to the interstellar medium, but over the decades and centuries, would keep knocking 9s off of its speed as a fraction of c. Using numeric approximation methods, we can calculate its speed in about 1 year as 0.99999999 c, 0.9999999 c in about 100 years, 0.999999 c in about 10,000 years, and about 0,999 c in about 10 billion years, roughly the current age of the universe.

[Moontanman]

CraigD said:

This is nearly, but not exactly correct. Bodies traveling even at very low speeds relative to an observer. For example, a 100 kg man walking at a typical speed of 1 m/s actually masses

That is, he gains about 625 nanograms - about the mass of a single human egg cell, or a small grain of sand.This is true only if the object is traveling in a perfect vacuum.

Interstellar space contains has a density of about 1 hydrogen atom per 1 to 10 cubic centimeters, or about to From this, you can calculate the power per unit area of friction for a spacecraft traveling in it as
.
Calculating this for the lower density for craft traveling at 0.1 c (As Janus did in post #32 of “Quickest way to get to The Super Earth”) gives a small, but troubling from a practical engineering perspective, . Calculating it for 0.99999999999 c gives about 500 million!

To put this into some kind of perspective, if the spacecraft used a plug of water ice near absolute zero as frontal shielding, this shield would be vaporized at a rate of about 3.2 meters of thickness per second!

In terms of conservation of momentum, ignoring the practical engineering problem of shielding and cooling, the density of interstellar space would produce an acceleration of

Even for a tiny spacecraft massing only 1000 kg with an frontal area of , traveling 0.99999999999 c, this calculates to about . In about 1 year, it would slow by about 3 m/s, to a speed of about .99999999 c. Friction would never completely stop it relative to the interstellar medium, but over the decades and centuries, would keep knocking 9s off of its speed as a fraction of c. Using numeric approximation methods, we can calculate its speed in about 1 year as 0.99999999 c, 0.9999999 c in about 100 years, 0.999999 c in about 10,000 years, and about 0,999 c in about 10 billion years, roughly the current age of the universe.

Thanks Craig, notice I did say theoretically:doh:, the interstellar medium is as much a barrier to near speed of light travel as the problem of accelerating to near light speed. Arthur C. Clark took this into consideration in the book Songs Of Distant Earth, the space craft used zero point energy to travel very close to the speed of light but it had to have a huge shield of ice to keep from being destroyed by the interstellar gas turned into cosmic rays by the ships speed. Even grains of dust caused huge craters on the shield. I'm not sure how to figure it but I'm sure there is a point of trade off where speed becomes deadly and it is probably considerably less than .99999 c

[The Transhumanist]

This post has been moved here.

[Moontanman]

[quote][quote name='Gardamorg']You know what would be even better?

Laser beams that are so hot and intense that they fuse and transmute matter in the back of a space craft into energy used to propel the craft.[/quote]

On the face of it not a bad idea. But I have yet to see any sign of anyone having a laser even close to being that powerful.


[quote]The ship's fuel will will undergo a series of stages, first, the fuel is raw hydrogen, second, a remote laser beam fuses and heats this hydrogen into plasma, this laser beam is very powerful, and fired from a solar powered space station/operating laser canon.[/quote]

As long as the ship is nearby not a bad idea.


[quote]In a few minutes, this plasma will be so hot that it will burn separate hydrogen into plasma without the need of a high powered laser, this will cause a chain reaction, the plasma will become so hot that it's atoms will release energy by themselves, and the hydrogen will become so hot that it will transmute into more plasma, which in turn will release more energy, making the craft self sustained.[/quote]


This sounds like tecnobabble to me, you need to give us some idea of how this works, I know of no way to do what you are talking about. Hot atoms do not spontaneously release energy, they only have the energy the laser has pumped into them.

[quote]The problem is the fuel (hydrogen) will be burned at an abnormal rate, which is why the hydrogen will be scooped up from the interstellar medium.[/quote]

Ok so you don't intend to carry your hydrgen with you?


[quote]It won't need a magnetic field because it's already moving so fast that it's speed will allow it to cover cover so much space in so little time, that it's speed compensates for the width a magfield would have to be.[/quote]

How do you scoop up hydrgon if it's not charged?


[quote]It can accelerate to this speed because it doesn't need energy at all, just hydrogen, the energy is supplied by the space station that fires the laser beam which splits atoms with heat alone, and after a certain point in time it doesn't even need the laser.[/quote]

A laser would only work at extreme close range, lasers spread out over time, by the time you were a few thousand miles away even the strongest laser would be spread to far to heat up anything to the extreme temps you going for. Also no amount of heat will split hydrogen atoms or any other atoms for that matter.

[quote]So this craft is in a sense, a ramjet, a laser beam powered space craft, and a self sustained fusion reactor.

It doesn't need charged hydrogen.[/quote]

To pick up enough hydrogen in the way a ram jet would pick up oxygen in the atmosphere would require it to be traveling a substantial fraction of C. Accelerating to that speed would require an enormous amount of hydrogen to start with and hydrogen fusion triggered by a remote laser would not be self supporting. Even if it was how would you restart it if you had to turn it off for some reason? also how would you decelerate at the end of your trip?

[The Transhumanist]

[quote name='Moontanman'][quote]

On the face of it not a bad idea. But I have yet to see any sign of anyone having a laser even close to being that powerful.




As long as the ship is nearby not a bad idea.





This sounds like tecnobabble to me, you need to give us some idea of how this works, I know of no way to do what you are talking about. Hot atoms do not spontaneously release energy, they only have the energy the laser has pumped into them.



Ok so you don't intend to carry your hydrgen with you?




How do you scoop up hydrgon if it's not charged?




A laser would only work at extreme close range, lasers spread out over time, by the time you were a few thousand miles away even the strongest laser would be spread to far to heat up anything to the extreme temps you going for. Also no amount of heat will split hydrogen atoms or any other atoms for that matter.



To pick up enough hydrogen in the way a ram jet would pick up oxygen in the atmosphere would require it to be traveling a substantial fraction of C. Accelerating to that speed would require an enormous amount of hydrogen to start with and hydrogen fusion triggered by a remote laser would not be self supporting. Even if it was how would you restart it if you had to turn it off for some reason? also how would you decelerate at the end of your trip?[/quote]


Right on top of it, realizing this I edited the post, and moved it to the BEC thread, before you posted.

[The Transhumanist]

My idea has been modified, see if it STILL has any flaws.

Gardamorg said:

If it were possible to teleport a craft's fuel, than it wopuld be possible to travel at light speed.

Once teleported, the craft's fuel will will undergo a series of stages, the fuel starts out as raw hydrogen, a remote laser beam fuses and heats this hydrogen into plasma, this laser beam is very powerful, and fired from a solar powered space station, that is also a very large Bose Einstein Condensate Transmitter, to teleport the fuel to the depths of our galaxy, it needs to be BIG.

In a few minutes, the plasma generated from the heating hydrogen will be so hot that it will burn newly arrived hydrogen (from a BEC Receiver built into the craft) into plasma without the need of the high powered laser.

This will cause a chain reaction, the plasma will become so hot that it's atoms will release energy by themselves, and the hydrogen will become so hot that it will transmute into more plasma, which in turn will release more energy, making the whole craft self sustained.

The craft requires NO energy, the space station that fires the laser beam is what acts as an energy source, it converts the fuel into energy, and over time allows to fuel to convert itself into energy, and the fuel is teleported from the space station's BEC Transmitter.

The Craft can be as large as needed as well.

Once the Craft reaches light speed, it can coast to it's destination.

[CraigD]

Gardamorg said:

My idea has been modified, see if it STILL has any flaws.

Yes, the idea of accelerating any sort of machine to the speed of light in vacuum in ordinary space is fatally flawed. These flaws have been explained so many times in so many books and websites that I won’t repeat them here.

Gardamorg, I recommend you try achieving about the same level of understanding of physics as the writers of Star Trek in the 1960s. These non-scientists knew you couldn’t accelerate to the speed of light, and that however you do it, spaceflight like they were depicting would require fantastic amounts of energy be stored in a small space, and without consulting blue ribbon panels of physicist and engineers (or even much talking among themselves), came up with a couple of not too unreasonable ideas:

• Since the highest possible energy density is found in antimatter (via annihilating it with matter), use antimatter fuel
  
• Since you can’t travel faster than the speed of light in normal space, don’t try, but rather change space (via “warp drive”)

Although actual physics (eg: the Alcubierre metric) suggest that many times more energy is required to do the sort of things depicted in Star Trek, we can at least give a nod to its science fiction writers’ guesswork as being roughly in the right direction.

In short, for spaceflight to be much different than it is now, we need to imagine spacecraft that are much different than they are now. Imagining larger, more massive ships with more powerful rocket motors doesn’t seem a productive line of thought.

While I’ve gone and brought science fiction into the discussion, I might as well trot out the time-worn idea that Star Wars is to blame for some “dumbing down” of the popular scifi audience. While both Star Trek and Star Wars are space opera – comedy and drama with scientific trappings, not science lessons with a supporting dramatic or comedic narrative – Star Trek, IMHO, better avoided the physically silly. The writer/producer system of 1960s TV that gave us Star Trek appears to have provided a better informal scientific peer-review process than the essentially single-handed (Steven Spielberg) writer/producer process that gave us Star Wars.