Original space travel idea?

[chrispenycate]

I'm not sure it would be possible to get enough information into a true nanite that the build up to a complex system would be possible. I know, practically all stories based round nanotech assume von Neumann capabilities, while all present experiments are concentrated on nanites created within a larger framework, and it's only faith that makes the linkage, but you could use larger projectiles, dust-grain size. The optimum would be that every particle contain all of the information, plus some limited read out and manipulative possibilities and energy handling - whoops, we're up to the size of a living cell.

The charged particles are going to actively repel each other, in orbit as well as in transit; outside of the nucleus electrostatic forces are among the strongest we know. You could possibly compensate for this by sending two beams from opposite sides of the solar system, intersecting at the target, where they attract each other and neutralise, so they can co-operate in building their larger structure. This still doesn't get rid of that relitavistic mV, which I can't see any mere planetary field absorbing (and atmospheric friction? On something that size with that much energy? I love the idea of the blue trails of Cherenkoff radiation as the individual nanites are heated to millions of degrees, massive cosmic rays colliding with air molecules, but there's no way to get rid of enough energy with a passage which doesn't include a fair amount of the planet's crust that they're not still way above escape velocity). Perhaps a close approach to the star, using its considerably more intense magnetic field to bend the beams into planetary orbit while decelerating them? Probably not, even then; there's really a lot of energy to dispose of.

And there's no feedback for the fractions of second of arc that make the difference between your target planet and a next door galaxy. Photon pressure, variations in solar wind; the slightest deviation at source, a touch of Heiseberg, or even a tough of Murphy, and there's no correction factor possible. Most of your original particles will be lost (which is why it's better not to distribute the data between lots of different travelling paths).

 

[Vertigo]

I agree with Chripsy your problem is going to be losing all that speed at the destination. Travelling at near light speeds mean that capturing the nanites into orbit would be almost like trying to capture the protons in a beam of light into orbit.

Not sure what the answer to that one would be, but I like the idea; quite novel!

 

[jastius]

chrispy this is why i think the best possibility at the moment is a fractal building type thing. if even one nano reaches destination then the fractrals will build into the the type of cloud machine matrix he is talking about. fractals are absolutely delicious, very complex results from small amounts of information and if you have converging fractals you can achieve something as complex as dna and even a human body. it would be possible in this manner if you had a chemical memory source to rebuild a human being upon another planet far far away... of course there is no guarantee that the individual thus created would run true to form.

and we are talking subatomics here. negligible size of discharge but more then enough to power up a building field inside the matrix. and i agree with you that the beam needs some kind of guidance, chrispy. i think reliance upon inertia is too problematic. that is why i suggested a renewing beam that would adjust to target upon each renewal. refocus, refocus, refocus...

as for tracking..though sound doesn't travel as fast as light you could use a sound pulse set off before the package was sent to bounce off the package and return at destination...
then you just wait for the call to come through.

 

[cakrit]

The optimum would be that every particle contain all of the information, plus some limited read out and manipulative possibilities and energy handling - whoops, we're up to the size of a living cell.

In my calculations, I have assumed nanites with mass ~10^-16Kgr, which is 100 times less than a cell and 10 times more than a virus. The heavier they get the more information they can carry and the more capabilities they can have, but the harder it is to accelerate them and charge them enough so that they can get trapped. Both of the latter are engineering problems of course and you can simply throw more money into them. The exact nature of such a cloud is definitely the most speculative part of the idea, but we know that nature has managed to build exquisite little machines that do a hell of a lot more than what we are asking here.

The charged particles are going to actively repel each other, in orbit as well as in transit;

I have to repeat that charges moving in the same direction actually attract each other, due to the magnetic fields they generate. The electrostatic force will come into effect if we slow them down before they lose the charge. I will try to do the calculations to see what exactly happens between two charges moving in parallel, but there should be an equilibrium distance inversely proportional to some power of the velocity.

You could possibly compensate for this by sending two beams from opposite sides of the solar system, intersecting at the target, where they attract each other and neutralise, so they can co-operate in building their larger structure.This still doesn't get rid of that relitavistic mV...

Yes, the first version of my idea had two beams travelling in opposing directions and colliding on the other side of the planet. However, the collision would most likely turn everything into a mess of exotic particles and high energy radiation. Moreover, the attraction would only manage to deflect most of the nanites and send them outside the orbit.

there's really a lot of energy to dispose of.

I know! I don't have an answer right now. My first idea was that the slowing down would be handled by the first structure they would build (let's call it the caterpillar stage). The caterpillar's job would be to collect the other nanites (how?) and gather enough energy (from photosynthesis or collisions with other particles?) to slow down, until it can enter a lower orbit. As it the machine grows, the orbit begins to be determined by gravitational rather than electromagnetic forces. There are quite a few ideas you have all proposed and I need time to think about them (or understand some of them!).

it's better not to distribute the data between lots of different travelling paths).

Definitely! We expect to lose most of them on the way.

 

[jastius]

but cakrit if they snowball they will slowdown.

 

[cakrit]

I was wrong regarding the attraction of moving charges. At the speed of light, the electric and magnetic forces would simply cancel each other. At anything below that, the electric force takes over and they start repelling each other. Wires with moving currents are attracted to one another because they are not charged, so the only active force is the magnetic one.

 

[cakrit]

but cakrit if they snowball they will slowdown.

As I said, I'm still trying to understand your idea. We have no idea of how exactly the 'snowball' is spinning at any given moment, so I don't know how it would know which way to eject (what and when?) to increase or decrease its momentum. It was your ideas that I need to think about, along with a couple of other suggestions. Analysis is easy. Synthesis is a bitch.

 

[cakrit]

but you take a whole wack load of positive and try to bounce it off its polar opposite, you have a whole bunch of sticky all of a sudden. stasis, and result in out-surge of energy.

I said before that I didn't get how the 'snowball' would be able to reduce momentum and then I thought that the above was what you expected would slow down the nanites. What exactly do you mean by the polar opposite? Where did we find the negatively charged pole? Magnetic poles are totally different.

 

[Abernovo]

I've never seen anything like this, so as others have said, it's worth looking at. Apart from the problem of losing speed and energy at the far end of the journey, I can see another potential pitfall.

That is, the actual motion of the stars and planets over time. Because everything is moving, you have to aim the beam to where the distant star or planet will be at point X, taking into account that you've got fossil light coming to you and fluctuations and wobbles may take place. The issue gets more complicated the more distant the target is, both with the lag in information and with more objects potentially crossing the beam's path.

There you are, having it planned out, and an asteroid, its orbit altered by an unexpected and uncalculated encounter with a gas giant's gravity, cuts through the beam, knocking 20% of the nanites out. The end result would be a failure, and you wouldn't even know it, unless you possessed a quantum entanglement messaging system (yes, I've been reading Nancy Kress ). This could be one of the touches of Murphy that Chrispy referred to.

Not a deal-breaker, but one that would require significant calculations on the team sending the nanites out and the smallest error could result in total failure, which itself could be a plot thread. I think you'd need a high redundancy level for the nanites.

 

[jastius]

according to this guy it is a multilayer field not just one pole or the other.

Magnetic fields of the earth

​

The Earth's magnetic field on Earth this is not equivalent to a magnetic dipole with magnetic S pole near the geographic north pole, and the magnetic field N pole near the geographic South Pole, but rather presents another special kind of magnetism . It is a natural phenomenon caused by the movement of liquid metal in the core of the planet and is present on Earth and other bodies celestesSol. as

It extends from the core gradually fading into outer space (no limit), with known electromagnetic effects in the magnetosphere that protects us from solar wind, but also allows diverse phenomena as the orientation of the rocks at mid-ocean ridges, the magnetoreception of some animals and orientation of people through compasses.

A compass points to the North-South direction because it is a magnetized needle immersed in the Earth's magnetic field: from this point of view, the Earth behaves like a giant magnet and has magnetic poles, which, at present, do not match with the geographic poles.

​

The South Magnetic Pole is 1800 kilometers from the Geographical North Pole. Consequently, a compass does not point exactly to the north geographically, the difference, measured in degrees, is called magnetic declination. The magnetic declination of the observation depends, for example currently in Madrid (Spain) is about 3 ° west. The magnetic south pole is moving through the northern Canadian northbound Alaska.
Posted by Saeed Halls in 15:53 ​​No comments:

 

[nightdreamer]

Even if it were a continuous beam of charged nanites we would be sending, my understanding from my physics days is that would actually become more focused. Moving charges generate magnetic fields in such a way, that they actually attract nearby charges moving in the same direction. It's the reason electrical wires attract each other. If you are aware of a different mechanism for ion beams, please share, I could not find anything.

Interesting that you brought that up, because there is a paradox there, and I forget how it resolves. From a "stationary" reference frame such as the Earth, then yes, it would seem that the beam would converge because of magnetic forces. But from the frame of the particles themselves, there is no motion, and so electric forces would cause the particles to diverge. The problem is, the same behavior must be observed from both frames. Either way, charged beams do diverge. I ran into this before and had a physicist explain it to me, but I've forgotten what the explanation was.

 

[cakrit]

Interesting that you brought that up, because there is a paradox there, and I forget how it resolves. From a "stationary" reference frame such as the Earth, then yes, it would seem that the beam would converge because of magnetic forces. But from the frame of the particles themselves, there is no motion, and so electric forces would cause the particles to diverge. The problem is, the same behavior must be observed from both frames. Either way, charged beams do diverge. I ran into this before and had a physicist explain it to me, but I've forgotten what the explanation was.

See post #26. I was wrong. At the speed of light, the two forces cancel each other out. Anything below that, dispersal. So you were right and I was wrong.

 

[nightdreamer]

Oops! Missed #26. Sorry. I figured out the difference with wires pretty quick, but was still bothered by the beam, because I knew that if the magnetic field transformed with velocity, then the electric field had to also, and that's something they don't teach you in freshman physics. I don't think we even covered it undergrad electromagnetics. I finally found what I was looking for here, but frankly, I got lost (twice) in the derivations, so I still don't understand it. I might run over to the physics department someday to get another explanation in English, but probably won't unless I really have to know. C'est la vie! Anyway, keep working on it.

 

[chrispenycate]

Encapsulation!

Our major problems are divergence of the beam due to electrostatic repulsion and lack of any auto correction once en route, right (apart from the nano bit, but that's just engineering)? And slowing down. So we build a container for the bits we want to arrive, and we don't give it a charge, we make its shell conductive. Quite a big shell, about the size of a pinhead, and sophisticated to the level of the nanotech. Now we use a Laithwaite linear accelerator – a 'rail gun', but the coils on this are spaced at planetary diameters, rather than centimetres, and the entire thing is a couple of AU in length (of course we build it in space; nowhere else is big enough). No rigid structure, you use laser interferometry to detect the precise position of the coils and adjust the polyphase generator to compensate for imperfections.

The shell is big enough that brownian movement due to photon impacts and random gas molecules is essentially eliminated, and sophisticated enough that it can be directed to make minor course corrections (extremely minor, but anything more than that would require fuel reserves, and a rapidly escalating mass/complexity. Better to accept a certain loss percentage).

Shortly before arriving in the target system it deploys its parachute, monomolecular thickness metallic film (any conductor, doesn't have to be ferromagnetic; Heinlein got it wrong in TMaHM) which uses photon pressure and solar wind as a first braking measure, dandelion seeds and was the conductor to which the linear accelerator applied the original forces to get it up to cruising speed (yes, you could deploy the parachute as soon as you've left the accelerator, build an immense laser bank/power generator in Mercury orbit and add a few more metres per second with photon pressure, but light sails are old hat ).

As you pass close by the planet you eject the nanites with enough velocity that they are captured into orbit, incidentally accelerating the empty capsules up to nearly as fast as their original cruising speed (yes, I know. Ejecting the nanites directly towards the parachute. Either you can use an annular parachute and aim through the middle, or gut your chute loose assuming the extra pressure on it will take it far away from your main container


Black marks; Vertigo, it's photons, not protons and jastius:- shame! Sound in space? It'd have to be electromagnetic, laser or maser, and could double up as communications and doppler radar.

And information theory states that, fractals notwithstanding, there is a definite lower limit to how much data is needed to describe a system of a certain complexity. If you wanted to describe a uric acid crystal or a honeycomb, that's very little data, if you wanted to describe a bee, or my toe joint in which that acid is crystallising, that's a whole different question, and if you wanted to describe the ecology, flowering plants and social insects you need masses more irreducible data. Not that we couldn't compress data a long way, but you can only acquire so much information, it is not infinitely expandable.

 

[Vertigo]

Black marks; Vertigo, it's photons, not protons and jastius:- shame! Sound in space? It'd have to be electromagnetic, laser or maser, and could double up as communications and doppler radar.

Whoops, missed that Chrispy, honestly, I did mean photons.

 

[jastius]

radiowaves chrispy, television transmission signals etc, not sound per se but a signalling device sent out before it is needed. then as the bitty bots cross the paths they recorrect their course. ... and i did say encapsulate the bitty bots.. i suggested an exterior matrix thingie to hold memory and rejigger more bitty bots en route.
and crispy if they can make an artery upon a computer bio-printer why can't the bitty bots carry the equations to reprint what is basically a two dementional vortex gateway splash-pad. the interstices of the fractals will coalese into the more complicated equations. we aren't talking about a star trek transporter on the first run out, only that would be possible with work to encode information that way and transfer it. and as for biomatter, chrispy you don't have to recode for the whole structure, only one living cell and a grow thing to prepare it in. it would hold its own instructions for reforming.
(and chrispy, you need more cranberry juice for your poor toes.)

 

[cakrit]

@crispy
- Getting rid of the charge when you no longer need it, is not that hard. If you negatively charge it you just create a spike on your surface, if you positively charge it you can either collect the electrons trapped in the Van Allen belt, or generate them. And of course, you could probably have an outer charged capsule that releases a neutral nanite. If the shell isn't charged when it gets there, my understanding is that you rely on gravity for the nanite that gets shot out of the capsule to orbit the planet. Correct?
- What kind of momentum reduction could we expect from such a sail? If we can slow down the structure enough, then there's no need to shoot the nanites in the opposite direction. We just reduce the speed enough for gravity to take over.
- If the momentum reduction is not enough, shooting the nanite in the opposite direction is certainly a good idea, but the energy required depends on the entire structure's momentum vs the mass of the nanite itself. If the capsule's mass is comparable to the nanite's mass we need a big explosion and it would be very hard for the nanite to survive it. If the capsule is much much heavier than the nanite, it will take a hell of a lot more energy to send it there.
- I'm not convinced that any course corrections will be feasible. The structure will probably be spinning like crazy, unless you include yet another mechanism, to correct for the spin (i.e. more mass and more energy).

One thing I never took account of in my calculations is the effect of the near-light speed on the momentum (the nanites will behave like they have more mass than they actually do). I just ignored gravity altogether and I think I need to add it to the calculations.

 

[chrispenycate]

Spike? You obviously didn't do valve electronics. Spike will work fine in atmosphere where there are some molecules to ionise; not so effective in vacuum.

Yes, I want the orbit set by gravity. It might pretty feeble relative to electro-magnetic forces, but it doesn't go round in pairs, attractive/repulsive, like girls at a dance. So it doesn't tend to cancel out with distance.

I really don't think we can get enough delta v from a light sail to bring us from relativistic speeds down to interplanetary, and gravity's not going to help. I was assuming nanites were close enough to solid state to take fairly brutal accelerations; I cheerfully admit it would be nice having a long, thin capsule so deceleration could be applied more gradually, but a) something long enough to make an appreciable difference would be more massive, more energy requiring in the launch system and b) – well, a needle just isn't as convenient a shape to steer as a sphere. Nothing to do with air resistance, just dynamic stability.

Oh, sorry. I haven't selected your idea to throw stones at, I just get this way occasionally. Most of the long term residents are used to me by now. Welcome to the Chrons; intense enough for you?

 

[cakrit]

Turns out that the gravitational force can be used only after we get down to around 10^3m/sec (for a geo-stationary orbit at around 10^7m). For a circular orbit, the mass of our object has nothing to do with it. The mass cancels out and the only things that matter are the orbital radius and the velocity.

 

[cakrit]

Oh, sorry. I haven't selected your idea to throw stones at, I just get this way occasionally. Most of the long term residents are used to me by now. Welcome to the Chrons; intense enough for you?

Are you joking? I'm loving this! But really, maintaining a high charge is much harder than losing it, due to field emission. I am finally able to post a link to my calculations.

We WILL get it (and I hope it will not require entering the atmosphere and magically surviving it).