Is star travel practical in theory now?

[EinsteinPD]

Rick_BN thank you for your Post. The belief that star travel and colonizing other Earth type worlds is not possible, is based on the very large distances involved, due to the very large times required to travel the distances ACCORDING TO NEWTONIAN MECHANICS, along with the limited human life span, as you correctly point out.

However, as the speed of light is approached time contracts or slows down, according to Dr. Albert Einstein's RELATIVISTIC MECHANICS.. This concept is implicit in Relativity, and has been experimentally verified with atomic clocks and subatomic particles.

Therefore, IF light speed can be approached, the time can be greatly reduced for the starship and its occupants. Then the problem reduces to obtaining enough energy to obtain adequate constant acceleration. Several months at two g's are required to approach light speed.

This is all explained and discussed in detail with references, in my ebook "Starship To New Earth Now." Please read it, thank you. If the price of $3.99 is a problem, just return it within the free trial period.

Time contraction is as sure as atomic energy. It is certain. And I suggest it makes possible star travel now. But the concept is so unfamiliar, that very few people know about it. Welcome to the very small club of people who do! The very great genius of Dr. Albert Einstein has given us atomic energy, and also the possibility of the starship.

Thank you again for your Post.

Phillip Duke Ph.D.

[kamas716]

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EinsteinPD wrote:

kamas716 thanks for your Post. In theory the fuel mass increase hinders acceleration, but also helps it to the same degree, since the fuel mass to be ejected also increases to the same degree. And, as the mass increases, time contracts. Therefore I suggest as stated in an earlier Post, the Relativistic mass affects will cancel. I could of course be wrong about this.

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Like I said before, it's been a couple of decades since I took physics.  But, I think you are forgetting that once you are at speed, and the mass of everything has increased, you then need to accellerate that fuel mass again to gain thrust.  Which means you must have more energy to compensate for the higher mass of the fuel to begin with.

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The Posters here seem to believe the necessary energy is the main problem. I believe that by carrying a sizable anount of fissionable material, and ice fuel, the energy will be adequate. If not, I expect an improved energy source will be found.

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Well, that last sentence basically says "No, star travel is NOT practical in theory now.

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My question is, why is it so important to you to believe it's not possible? I am quite willing to say it may not be possible, but that is very far from its being proven impossible.

Best regards,

PD

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It's not important for me to believe it's not possible.  But, from my limited understanding of relativity I think you are missing a fundamental part of the propulsion problem. 

[ManuelGarcia]

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kamas716 wrote:

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But, from my limited understanding of relativity I think you are missing a fundamental part of the propulsion problem. 

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One of the things he is overlooking is the fuel required to accelerate fuel.  It is correct that the energy required to decelerate a couple thousand pounds of payload is the same to accelerate the same weight.  But is all the fuel is used to accelerate to 0.1c there is none for deceleration.  So if it takes 50,000 pounds of fuel to decelerate a payload of a few thousand pounds. Then you have accelerate the couple thousand pounds of real payload plus the 50,000 pounds of fuel needed for deceleration. That is why an addition 2,500,000 pounds of fuel are required to accelerate the payload and 50,000 tonnes of fuel up to 0.1c so there will be fuel to decelerate to 0. That is why the project Daedalus was designed as a flyby mission.

Now while project Daedalus is over, project Icarus is just starting to redesign the interstellar spacecraft to see what can be improved based on today's technology. Their objectives include

1. To motivate a new generation of scientists in designing space missions that can explore beyond our solar system.

2. To generate greater interest in the real term prospects for interstellar precursor missions that are based on credible science.

But both Daedalus and Icarus designs depend on development fusion based space propulsion. 

[ManuelGarcia]

Note in a couple of places I wrote pounds when I meant tonnes

example I meant to write 

So if it takes 50,000 tonnes of fuel to decelerate a payload of a few thousand pounds. Then you have accelerate the couple thousand pounds of real payload plus the 50,000 tonnes of fuel needed for deceleration. That is why an addition 2,500,000 tonnes of fuel are required to accelerate the payload and 50,000 tonnes of fuel up to 0.1c so there will be fuel to decelerate to 0.

[EinsteinPD]

kamas718 and ManuelGarcia thank you for your Posts. The consideration that as the Starship approaches light speed the fuel mass increases, while the reactor energy remains the same, is compensated for to a certain extent by the travel time contracting. To what degree these considerations all work together regarding star travel, is IMO not clear.

It may well be true that the Starship will require a propulsion system other than Uranium fission. But as long as the entire comcept of star travel is conbsidered inherently impossible, then no real progress will be made in this direction. I am pleased that I have brought this subject of star travel, and colonizing Earth type worlds, to discussion.

My book discusses in addition to the propulsion system life support, crew selection, life on other worlds, ET encounters, etc., all subjects of interest to potential star voyagers. Evidently no one has looked at the book "Starship To New Earth Now.".

I really do not have the time to continue with this thread. You are welcome to continue it without me. Thank you all for your Posts, and your interest. Good-bye and good luck.

Phillip Duke Ph.D.

[Ebook_Pioneers]

It will never be doable unless something like subspace travel becomes a reality, and that's highly unlikely.

Obviously no one will ever travel in normal space anywhere near light speed. Even at 1/10 of light speed your ship would be completely wrecked by meterorites within the first moments of travel. A speck of dust might be all it takes at those speeds to disintegrate your entire ship.

[Ebook_Pioneers]

"Just something I thought to mention is that time and distance are not the problem. It is the lifespan of humans that is a problem."

I wouldn't be so sure. People assume things do not deteriorate in space when in fact moisture is often a problem in cold extremes adding to corrosion of everything including circuitry. Part failures are bound to happen within a few years.

[Ebook_Pioneers]

B&N will have to come out with a keyboard version before I'd consider it probably. I have both a Nook and a Kindle-3 (Keyboard) and use the K3 almost exclusively because a real keyboard is much easier to use than a silly touch screen, and any serious reader takes lots of notes. Touch screens have no reason to exist other than to be a headache to their owners. I like how the glowlight works very much though. Beats the heck out of my Kindle's lighted case. But if Amazon offers the K3 with a similar glowlight next year, it's a no-brainer which is going to be best to own.

[Ebook_Pioneers]

That last post was supposed to go into the Nook Simple Touch forum. I have no idea how it ended up here.

[Omnigeek]

I'd be careful about saying "never".  While Dr. Duke's grasp of the equations and complexities appears inadequate, other scientists like Dr. Robert Forward have previously presented quite plausible technologies.  Plausible in that they worked the equations correctly and accounted for the masses involved -- even Dr. Forward would have admitted the odds against building a laser and solar sail spacecraft to the proportions he envisioned would be daunting.

Yes, a very small object at 0.1 c has tremendous kinetic energy but the particle densities in interstellar space are vanishingly thin.  In addition, something like a Bussard ramjet would suck in the meteorites you postulate and use them as reaction mass.

[EinsteinPD]

Omnigeek, in the previous thread I started on this subject you (and a few others) attacked me so viciously that the Moderator eliminated the entire thread.

Now according to you my "grasp of the equations and complexities appear inadequate." Based on WHAT? The equations you never posted? Statements you never made? Differences of opinion due to firmly held beliefs of other Posters, that star travel is intrinsically possible?

FYI I wrote and published an ebook on the entire subject. It gives references to Dr. Einstein's work. Not a single Poster on this thread including you, has ever bothered to read the book. Instead you attack me personally.

I am not going to allow you to get away with this again, and I will now file a second xomplaint about you and your derogatory Posting with the Forum Moderator. If you cannot be civil, and stick to the issue, but insist on negative personal statement, just go away and do NOT post more negative personal statements about me on my thread.

[orb9220]

Hmmmm I'm confused as read the whole thread and didn't see any derogatory statements or uncivil behavior?

But questioned & attacked? more like challenged your statements & beliefs but not you personally.

So don't get the over-reacting and threating to pull in the moderators and such.

But what do I know as I'm No Rocket Scientist :-)
.

[Ebook_Pioneers]

"something like a Bussard ramjet would suck in the meteorites you postulate and use them as reaction mass."

A couple of problems with the ramjet scheme: it depends largely on collecting hydrogen from space as it travels. But most of space is made of dark matter. Even the Milky Way has ten times more dark matter than regular matter. And where you find dark matter you find very little hydrogen. And there's too much dark matter to bother trying to avoid it all at anywhere near light speeds. Also, a ramjet's ion scoop would be no help at all with larger meteorites, which again, are everywhere. If one the size of a baseball didn't get you, one the size of a locomotive would.

I once tried to come up with a way to get through the meteorites and that was by using a small antigravity drive that would be used exclusively for exerting a pushing force from all sides of the craft. Obviously the pushing force for rear thrust of the craft (from a much more powerful antigravity drive) would have to be much greater if it was going to move at all, but the idea was to literally push objects like rocks and ice chucks out of the way as you came to them (or as they came at you from above, below, or the sides). The problem with this notion is the Newtonian law of equal reaction. When your ship came up against an object with much greater mass, say a meteor the size of a football field. Instead of you moving the meteor, the meteor would move you, and at such a great force that no one could survive the whiplash effect. In fact, traveling at just 20,000 miles per second you would come upon meteors that big every second or two and end up being jerked around like a pinball without ever actually touching a single meteor. Another theory up in smoke.

Personally, I just don't think it can be done. It's like trying to throw a feather across the Atlantic. I noticed that Arthur C Clarke said in the forwards to a couple of his later novels that interstellar travel seemed hopeless. At least I'm in good company.

I think that, to date, the most feasible way of interstellar travel in a novel came by way of the last book in the Ender Quartet: Children of the Mind, where objects (including people) were sent into nonlocality (or call it subspace or hyperspace if you like) and then immediately popped back out again in a different part of the galaxy. Of course there are myriad problems inherent with using nonlocality for travel, but Card was smart enough not to get into much detail.

I have nothing against people here trying to figure out some mode of interstellar travel. I don't think it can be done in real life, but that doesn't matter anyway. You only need to come up with a way that doesn't seem incredibly far fetched so that it works in a story. In fact using a ramjet in a story (or something like one) might work just fine as is. Just state that some unknown scientist in the future managed to overcome the problems with it and leave it at that. No need to go into any more detail for a story in my opinion.

PAX

[ManuelGarcia]

EinsteinPD I don't see any derogatory statements in this thread. I suggested that it would be beneficial to read up on the spacecraft physics and you said that was derogatory. But I didn't mean it as derogatory, just that if you are going to talk/write about rockets it would help if you knew the terms.

I gave figures based on the energy that a perfect fission reactor could produce and showed why that it wouldn't be possible for a rocket with a perfect reactor to get a spacecraft to any significant fraction of the speed of light. You didn't give any support for your figures. 

This is what NASA says

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http://www.nasa.gov/centers/glenn/technology/warp/ipspaper.html

Just how limited are rockets for interstellar travel? Although rockets are reasonable for journeys into orbit or to the moon, they become unreasonable for interstellar travel. If you want to deliver a modest size payload, say a full Shuttle cargo (20,000 kg), and you are patient enough to wait 900 years for it to just fly by the nearest star, here's how much propellant you'll need: If you use a rocket like on the Shuttle (Isp~ 500s), there isn't enough mass in the universe to get you there. If you use a nuclear fission rocket (Isp~ 5,000s) you need about a billion super-tankers of propellant. If you use a nuclear fusion rocket (Isp~ 10,000s) you only need about a thousand super-tankers. And if you assume that you'll have a super-duper Ion or Antimatter rocket (Isp~ 50,000s), well now you only need about ten railway tankers. It gets even worse if you want to get there sooner. 

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That is about 0.5% of the speed of light. Unlike me they calculated based on a realistic reactor, where as my figures were for a perfect reactor.

And no I haven't read your book, no more than I would read a book that claimed a single stage rocket with kerosene and liquid oxygen for fuel could be used to colonize Mars. I was just giving some mathematical reasons why it couldn't be done with today's technology no matter what your book says. The same thing applied to the Wright brothers, no one could have achieved  powered flight with a steam engine. The airplane had to wait for internal combustion engines which had a high enough power to weight ratio.

[BrandieC]

@EinsteinPD:

The fact that you referred to this thread as "my thread" illustrates why I think you find many of the participants on these boards hostile to your posts.  While you may have started this thread, once started it became a forum for all participants, even those who disagree with your views.  I don't have an opinion on the subject of this thread, nor do I pretend to understand the various technical issues which have been discussed here, but it seems to me that those who have stated views contrary to your own have done so by citing specific data, not by engaging in ad hominem attacks.

Before Omnigeek's post which you seem to find so offensive, you said that you "really do not have the time to continue with this thread" and that the other posters were "welcome to continue it without [you]."  It goes without saying that others are welcome to continue the thread; it doesn't belong to you.  If you think that the best way to deal with disagreement is to threaten to "call Mommy," perhaps you should return to your original plan to stop posting to this thread.

[deesy58]

Hmm.  I seem to recall that there is a very great deal of difference between the nuclear power plants that drive submarines, surface ships, and electrical power generating plants, and the type of nuclear power plant that would be required to propel a ship in empty space.

First of all, I seem to recall that water is NOT used as a fuel in the nuclear power plants used by the world’s navies and electrical generating plants.  It is simply a source of steam used to drive steam turbines.  The steam loop is a closed loop, thereby ensuring that radioactivity cannot leak into the environment.  After the superheated steam leaves the turbines, it passes through a heat exchanger that condenses the steam back into superhot water before it is returned to the boiler to be converted, again, into steam. 

The excess heat that is gathered by the heat exchangers must be discarded.  This is accomplished by a second, open cooling loop that channels the hot water through the familiar cooling towers, or into a lake, river or ocean.  The primary byproduct of a nuclear power plant is heat, not steam.

The United States government conducted experiments on nuclear rocket propulsion at the Nevada Test Site a goodly number of years ago.  They were so unrewarding that I believe the project was abandoned as being not sufficiently efficient to be workable.  A little research will probably provide additional details about the project.

It seems likely that a propulsion system that used steam that was converted directly from water by the heat from nuclear fission would require an enormous amount of water fuel, whether it be in the form of ice, or in the form of water.  In such a system, water would be one of the two fuels required for propulsion (the other being a fissile material), and all of that water fuel would be lost during propulsion, unlike a submarine, surface ship or nuclear power generating plant, which do not “burn” water. 

Food for thought. 

[ManuelGarcia]

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deesy58 wrote:
The United States government conducted experiments on nuclear rocket propulsion at the Nevada Test Site a goodly number of years ago.  They were so unrewarding that I believe the project was abandoned as being not sufficiently efficient to be workable.  A little research will probably provide additional details about the project.

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This was project NERVA it had the goals of

1. Demonstrating engine system operational feasibility
2. Showing that no enabling technology issues remained as a barrier to flight engine development.
3. Demonstrating completely automatic engine startup.

It met the goals and was deemed adequate for Mars missions being planned by NASA. 

The project wasn't killed because it couldn't work, but for political reasons. The Mars mission became NERVA's downfall. Members of Congress in both political parties judged that a manned mission to Mars would be a tacit commitment for the United States to decades more of the expensive Space Race. Manned Mars missions were enabled by nuclear rockets; therefore, if NERVA could be discontinued the Space Race might wind down and the budget would be saved. Each year the RIFT (Reactor-In-Flight-Test) was delayed and the goals for NERVA were set higher. Ultimately, RIFT was never authorized, and although NERVA had many successful tests and powerful Congressional backing, it never left the ground.

See

To the End of the Solar System  

Note NERVA engines used specially built reactors and used Hydrogen for propellant, not water because hydrogen produces a higher specific impulse.

So this type of engine could be used to get around the solar system, but not for interstellar journeys.

[EinsteinPD]

BrandieC, the Forum moderator has asked me not to reply to derogatory comments, but to contact him instead. So I am doing that. I will say that I used the term "my thread" because I started it, and have put a lot of time into it. Omnigeek (and you) and a few other Posters prior Posts were so offensive that the Moderator removed the entire thread. That is a fact.

I do not as you state "call mommy" but do as the moderator requires. Give your anger a rest.

[EinsteinPD]

Hello orb9220, in a prior thread on this subject I was attacked by Omnigeek and others to the degree that the moderator eliminated the thread.

Omnogeel's recently Posted statement that "Dr. Duke's grasp of the equations and complexities appears inadequate" is a derogatory statement. The entire thrust of my numerous Posts relates to "equations and complexities."

The moderator has directed me to contact him. So I am not "overreacting and threatening to pull in the moderators and such" as you Post.

[EinsteinPD]

Hello Manuel Garcia: To avoid possible misunderstanding, IMO your Posts are never derogatory, they have been helpful to the thread, and I have no problem with them.

My book contains material related to star travel and colonizing other worlds, ETs, etc. The subject of starship propulsion is treated in more detail there, than in these posts. Due to your interest in and grasp of the starship subject, I hope that you will read it.

If you check the historical record of very early heavier than air flight, you will see that Langley constructed a steam powered small unmanned airplane that flew 5 miles, years before the Wright brothers. It used to be displayed in the Smithsonian museum. I saw it- he employed a flash steam boiler.

Unfortunately I do not have time to continue as I would like on this thread, but in trying to close on it say this. My book's purpose is to generate interest in starflight, and it is doing that, even if to a lot of criticism. It may well be that a different propulsion system is required. I believe the only way to know for sure, is to build and test a starship prototype. It was by repeated attempts that the sound barrier was broken, and the Wright brothers flew, and probably it will be by repeated attempts, that star travel will be achieved.

Thank you for your interest, and your Posts.

Phillip Duke Ph.D.