Your ideal Interstellar vehicle/system (no FTL)

[AngelLestat]

20 hours ago, K^2 said:

Because this is a lattice computation, it would inherently look at the ground state of the system. I'm not going to look at how outgoing flux of gamma radiation is going to affect the system. What I'm worried about is black hole munching on the electron cloud, which can be determined from the ground state. Since everything is far above Plank scale, QED is sufficient to describe it. Whether or not the flux is going to be sufficient to blow away the electron cloud is a separate question, but that can be estimated separately from ionization energy, which this computation will provide me.

Is your area.. good luck with those estimations, if you pursuit enough details this can be even a paper material. 

20 hours ago, K^2 said:

I might be completely wrong about being able to reduce degrees of freedom for this problem, though. If I have to run an actual 3+1 dimensional simulation, I won't have sufficient computing power. And I don't think I have access to any super clusters anymore. I miss being able to just SSH into a system that gives me access to 800+ GPUs for parallel computing. *sigh*

Heh, how much people use it at the same time?

 

16 hours ago, PB666 said:

You cannot focus 600,000 mas equivilance of gamma ray energy on a single point 10-19 radius because of heisenberg uncertainty. 600,000 kg of mass equivilant of gamma itself exceeds the amount of electrical energy humans have ever produces by 10s of magnitudes. We can fuse hydrogen atoms after they have absorbed neutrons, this occurs during the breeding reaction. Dueterium. Fusion energy works the current thermodynamics of the reactors do not, this is because heat and plasma containment are quickly lost.

I never said that is possible, I just answer you how it could be done with enough technology.
Not sure what are you trying to said in your fusion argument.. just answer how much deuterium and lithium you need?

16 hours ago, PB666 said:

I watched a guy pummel a one inch thick piece of titanium with justa about every form of high powered rifle even a fifty calibre coukd not break it. You body is constantly being bombarded and you survive, Mars on the other hand withou a magnetic field bombarded by 250000 m/s solar wind lost all its hydrogen. More is very different from more poweful. I can drop a bullet 1700 times on your arm from a few inches up with a contact velocity of 1 mph, you would have a bruise and contact dermatitus, however if i fire a 50 at your arm you might find some of its remains. When that 50 cal bullet hits your bone, the bone fragments become the projectiles that tear off the rest of your arm. 

At close to c collision between molecules and larger atoms will then to create a shower of atoms some that can even pass through metal, to give an example when asteroids strike the earth a 25000 m/s there is radioactivity released depending on the composition of the soil and meteor, typically there is an iridium signsl associated with soil layers. The faster moving the object the more high energy particles will be produced. 

I don't see nothing useful in your argument to defend your posture.
Again.. few layers of graphene, hits the grain of dust or atom in a rain of ionized particles that can be deflected using a magnetic shield.
I can show you several links where good physicists play with these issues and how they solve them.
They almost all agree that you can reach 0,8 or 0,9c without a big issue with what we know about the interstellar medium.
Take a look to the Venture Star from Avatar movie, is not a perfect example, but it gives you an idea on the area exposed vs your ship.
It can have even artificial gravity by propulsion instead rotation, and when you turn around at the middle of your trip to start the slow down, the same propulsion will clean your path.  
 

[PB666]

2 hours ago, AngelLestat said:

Is your area.. good luck with those estimations, if you pursuit enough details this can be even a paper material. 

Heh, how much people use it at the same time?

 

I never said that is possible, I just answer you how it could be done with enough technology.
Not sure what are you trying to said in your fusion argument.. just answer how much deuterium and lithium you need?

I don't see nothing useful in your argument to defend your posture.
Again.. few layers of graphene, hits the grain of dust or atom in a rain of ionized particles that can be deflected using a magnetic shield.
I can show you several links where good physicists play with these issues and how they solve them.
They almost all agree that you can reach 0,8 or 0,9c without a big issue with what we know about the interstellar medium.
Take a look to the Venture Star from Avatar movie, is not a perfect example, but it gives you an idea on the area exposed vs your ship.
It can have even artificial gravity by propulsion instead rotation, and when you turn around at the middle of your trip to start the slow down, the same propulsion will clean your path.  
 

First, I don't use movies as a judge of what is and what is not possible, and second with regard to your physicist claim that is at 0.8 or 0.9c, since we do not have a method of reaching that velocity we have to consider the potency to catastrophic impacts at lower speeds.

If we ignore reaction mass, the very best you can do (c2/2) = 0.707c, That is not accounting for the mass on board to slow the ship down. The BH drive is producing EM which generations N per 300MJ of Energy. If the wormhole is initially 1/2 the ships weight, and E = mc2 the 0.5*9E16 = 4.5E16 joules. The average accel mass is ~0.8 and average decel mass is 0.6 which means we use  2.6E16J per starting ship mass on accel leg and 1.9 on the decel leg. Therefore on the accel leg you can produce 86666667N per starting mass over and average relative to starting mass of 0.8 which ends up begin 108333333 or 0.36C and deceleration at 105555556 0.35C. That assumes that all radiation is perfectly radiated backwards behind the ship. Assuming the perfect angle is theta and the average radiation vector is 45' then the cosine of 45 is the efficiency which at 0.707 is going to set that theoretical maximum at 0.25c. Some of the radiation will be used by the ship, and wasted. Also as the blackhole shrinks it eventually becomes unstable and has to be ejected, so at best you are probably looking at 0.2c. 0.8 or 0.9c is a mindless fantasy. Of course if you did not need to decelerate and you did not care about loss of life or material to explosion, i.e. you had a supernova mindset you could have some particles reach near the speed of light.

 

Edited February 17, 2016 by PB666

[K^2]

13 hours ago, AngelLestat said:

Heh, how much people use it at the same time?

If you don't ask for more than 200 cores, the "line" is usually about a day. If you need just a few cores, you can get execution time within an hour, but there is little point then. I had access to a cluster with 24 cores without waiting.

[magnemoe]

On 16.2.2016 at 6:40 PM, PB666 said:

First off Interstellar - period - is currently out of our reach, so your argument is just silly and stupid. The argument is given the current limitations what is the most feasible, this is it, K2 as you note abdicated on his responsibility to tell us how he was going to produce a black hole at 10^-19 meters in diameter. Everyone else has methods that are fail.

Second on a ship that is .32 km in diameter there is ample enough room to grow food, to build factorys that can build fusion reactors, store dueterium and hydrogen (tritium cannot be store because it has a half life of only 12 years) or whatever the ship needs. One assumes that the ship is dominated by multitasking robots, that the supplies of raw materials are stocked on board, In addition in the center of the ship one could have a rotating habitation area capable of producing 1g for the inhabitants to work out or do other gravity requiring tasks (again at 0.32 km, this is not a particular problem).

Third, given a fusion power reactor capable of producing 100 MW of power, you have a power supply that can potentially last generations, therefore all you need is a capacity to produce LEDs in the red and blue spectrum and you have food and oxygen. Fusion power gets its fuel from hydrogen, very little hydrogen is needed and potentially can be extracted from space using a collector at the front of the vessel, or could be carried on board. Product Helium would be used for impulse production. Again on a ship of 0.32 kilometers you can have several of these, so if one reactor goes down you have back ups.

Forth, since current energy requirement prevent speed of light, most you are going to see for a start/stop (which BTW even optimistically is impossibility) of 0.1C the collisions even a grain of sand or space dust in space, would be catastrophic. E = 1/2mv² our dust weighs .0000001 kg = 45000000 Joules. A 50 calibre car killing rifle bullet is 18,050 Joules, In other words you have 2500 times the amount of energy hitting 1/1000 th amount of space. The RML 8 inch howitzer (The type of artillary that can tear down a 12 inch concrete wall) produces a 26900100 is only half the amount of energy as that piece of space dust. So, yeah, fractional c has a big impact problem. At a million meters per second, that is 1/300th of C (1/30th of 0.1c) the relative kinetic energy of impacts is 0.1% so instead of that grain of dust hitting with a force of 2 howizter bullets it hits with about three times the energy as a a 50 calibre bullet, A covering of solid titanium about an inch thick can stop this. Somewhere around 5 million meters velocity relative to intergalactic medium is the practical safe limit of space travel, everything faster is risking almost certain catastrophe. Solve the howitzer shell impactor problem and we can talk about the other non-functionalities of your ideas. 

Fifth, No one has any idea how to safely create a black hole of 660 tonnes. Its a fantasy, chances are if you created it here on earth, it would destroy the earth, so. . . . Far as I know fusion reactors don't have that problem. Solar sails are toilet paper pretending to be a source of force.

An black hole drive would be past pointless going at 0.0033 c, use orion its far simpler. Going at 0.1c or higher require more advanced drives like black hole, antimatter or laser pumped solar sail. 
Orion should be able to get 0.03 c fairly easy, much faster and you start running into the rocket equation pretty hard.is t 
Yes this is an generation ship too 133 year to alpha centaurs.

Regarding impact during travel, first we do not know how much micrometeorites its in interstellar space but it should be far less than the inner solar system. 
An common way to deal with it while keeping mass down is many thin layers of armor, the impacts at this speeds will be more like energy weapons, hit and the impactor and an part of the shield is plasma moving inward.
plasma disperse so the next layer will just get heated up. Yes at so high speed plasma might not get dispersed enough however during cruise you could even have the shield flying free in front of you, the shield would be made of empty fuel tanks and similar. it will take damage and would need repair by robots on it. 
This is problems but far simpler than using over ten times as long traveling and keeping everything running for so long. 

How far forward do the shield need to be, how much of it will vaporize on impact guess effect here is heat radiation from the impact, how thick does it need to be. 
Note that you will have an extra shield closer and finally the front armor or impact zone, empty fuel tanks mostly. 
Lasers, magnetic fields and cold plasma is also solutions to this, probably in an combination. 

 

[PB666]

Here is a o.1 scale prototype of a generataional ship

Note that kerbal only allows to show so many kerbals so the 24 that are on this ship are not shown.

Each cell in the full scale mode has a 250 MW fusion reactor, the ISP is 2500000 (velocity = 25 million about 0.08c)

Each reactor is separated by 80 feet in a full scale model and each wall along the line between reactors is about 8 meters of titanium, the fins are for heat dissippation the bottom of the fins are passive liquid sodium photon drives, primary coolant to liquid sodium liqud gas phase water cooling system. The drive are VASIMR type drives. Hull is 10 cm thick titanium, the actual ship would have 500,000,000 units of propellant plus dueterium and hydrogen.

 

[PB666]

1 hour ago, magnemoe said:

An black hole drive would be past pointless going at 0.0033 c, use orion its far simpler. Going at 0.1c or higher require more advanced drives like black hole, antimatter or laser pumped solar sail. 
Orion should be able to get 0.03 c fairly easy, much faster and you start running into the rocket equation pretty hard.is t 
Yes this is an generation ship too 133 year to alpha centaurs.

Regarding impact during travel, first we do not know how much micrometeorites its in interstellar space but it should be far less than the inner solar system. 
An common way to deal with it while keeping mass down is many thin layers of armor, the impacts at this speeds will be more like energy weapons, hit and the impactor and an part of the shield is plasma moving inward.
plasma disperse so the next layer will just get heated up. Yes at so high speed plasma might not get dispersed enough however during cruise you could even have the shield flying free in front of you, the shield would be made of empty fuel tanks and similar. it will take damage and would need repair by robots on it. 
This is problems but far simpler than using over ten times as long traveling and keeping everything running for so long. 

How far forward do the shield need to be, how much of it will vaporize on impact guess effect here is heat radiation from the impact, how thick does it need to be. 
Note that you will have an extra shield closer and finally the front armor or impact zone, empty fuel tanks mostly. 
Lasers, magnetic fields and cold plasma is also solutions to this, probably in an combination. 

 

If you are traveling about 0.01 c you can basically assume that the first atom/atom impact with begin a cascade (since this atom will smash into other atoms, passing around most but occasionally hitting a few) Electrons create repulsion, so if the electrons do not have time to create charge density in front of the atom, you can look at the frequency of electrons is particular orbitals, in the time interaction begins until the time two atoms might collide you get an atom smashing event, even at 0.8 to 0.9 c. Most of these will be elastic (non-nuclear) some will produce radioactivity. You can control this by using certain kinds of material in the hull, but you can't control the constituants of space, and unstable nuclei might just relieve themselves of a neutron. As you approach C the impactors atoms appear more massive, and so on impact they would have a tendency to do more damage. So the atoms first line of defense is the electron shield this shield covers the crosssectional area of the atom as two atoms collide, if the atom is going fast enough the reaction time of electrons is too slow or the repulsive force is too weak. In either case electrons get stripped of their outer shell electons and this results in highly increases chemical reactivity and heat generation. The next point of elasticity are the nuclei, the nuclei are essentially around 10E-15 across about 1/100000 the diameter of an atom, so its cross sectional area is 10E-10 of the entire atom. However, alpha particles do not have enough energy to penetrate to the center so the effective 1/1000000 the size of an atom from a scattering point of view. We can do some calculations, if we assume that a ship is going about 0.01C and an atom is about 10-10 thick, then how far does an atom have to travel before it is scattered by another atom. The answer is 1000000 x 10E-10 or 10-4 meter or about 0.1 mm. This means at this speed just about all atoms not repelled by electrostactic forces will undergo deep nuclear interactions. As speed increases the thickness at which this occurs decreases so that around 0.06c you can go deeper about a millimeter, before this type of scattering is observed, but at this speed nuclei are beginning to actually penetrate the nucleus itself. Rutherford showed that at about 0.01 C the collision of alpha particles with protons is elastic, the charged particles repulse each other, however even before this charged particles repulse each others. The level of scattering is far greater.  Once you get over 5 MeV per charge the nuclie can  slip into the nucleus itself which places its speed at about 0.06 C. So basically thats the speed limit that you don't want to cross, but again that is for certain nuclei, in which case its much lower, an atom like tritium that has three nuetrons per proton and hydrogen would have more momentum per charge. So at 0.06 C on average whatever type of shield material you have, it will not behave as a shield anymore and the atoms within the shield will begin behaving, when struck, like small atomic weapons. The critical feature is that they will increase temperature and pressure on surrounding materials making for alot of unwanted physics. By increasing the heat and pressure it becomes more likely that surrounding atoms of both ship and impactor begin interact, for example increasing the density of nuclei at the impact point, scattering nuclei, increase the path through the ship that they travel, increasing the level of positive charge, therefore increasing the likelihood that an impactor atom will change course and finally increasing the likelihood that a nuclear reaction takes place. Of course some of the surrounding metal will just vaporize into space, a good thing, but the underlying metal almost certainly deforms, thins or cracks. This is a problem as you increase speed even more, because eventually those nuclei no start interacting with the pressure hull of the ship, this does not mean it collapses or explodes, but the strength of the metal will decrease and eventually fail. Thin layering is not necessarily protective since solid/gas phase transition between the layers can cause them to separate and opening up huge areas to higher risk, just like a poly-wall tire that overheats due to stress and overheating. 

http://resources.schoolscience.co.uk/STFC/16plus/partich1pg3.html

Again, space is very thin, but alot of the stuff in space are plasma, good because the electrons will simply travel over the hull of the ship, bad because the dissociated nuclei have no outershell electrons to prevent them from bombarding the shield proton. The solar system is in a rather cold spot in local space, but as you travel you will travel through hot spots and places where ejecta from long since dead supernova cross the path of the ship. These areas almost certainly contain some condensates.

 

[magnemoe]

Ok so front shield get radioactive, note that this only affect the front you travel so fast you will not get anything from the side. 
This might be bad for stuff like solar sail or medusa. 
This will also create an issue for the forward thin shield.

An positive charge will deflect protons however I doubt it would be strong enough to deflect them at this speed? 

[AngelLestat]

13 hours ago, K^2 said:

If you don't ask for more than 200 cores, the "line" is usually about a day. If you need just a few cores, you can get execution time within an hour, but there is little point then. I had access to a cluster with 24 cores without waiting.

Ok bad news, maybe I will save you some work.. I read the original paper from Crane on BH propulsion.
He said that if the black hole is charged or spinning, then it release its power much faster, (the second until its spinning stop) not sure why..
Also no sure why you said that only QED can explain it, the gravity in this case is enough strong to change things very differently at quantum distances..
In other words, 1000 attometers of difference in a big black hole means nothing, no change on gravity, but on a SBH there is a huge change.
So it will need quantum gravity?
Here's the original paper, is interesting.
http://arxiv.org/pdf/0908.1803.pdf
 

6 hours ago, PB666 said:

First, I don't use movies as a judge of what is and what is not possible

It was only to explain you how a thin and long ship might looks like... Also.. that ship was carefully designed for a scientist. 

 

6 hours ago, PB666 said:

If we ignore reaction mass, the very best you can do (c2/2) = 0.707c, That is not accounting for the mass on board to slow the ship down. The BH drive is producing EM which generations N per 300MJ of Energy. If the wormhole is initially 1/2 the ships weight, and E = mc2 the 0.5*9E16 = 4.5E16 joules. The average accel mass is ~0.8 and average decel mass is 0.6 which means we use  2.6E16J per starting ship mass on accel leg and 1.9 on the decel leg. Therefore on the accel leg you can produce 86666667N per starting mass over and average relative to starting mass of 0.8 which ends up begin 108333333 or 0.36C and deceleration at 105555556 0.35C. That assumes that all radiation is perfectly radiated backwards behind the ship. Assuming the perfect angle is theta and the average radiation vector is 45' then the cosine of 45 is the efficiency which at 0.707 is going to set that theoretical maximum at 0.25c. Some of the radiation will be used by the ship, and wasted. Also as the blackhole shrinks it eventually becomes unstable and has to be ejected, so at best you are probably looking at 0.2c. 0.8 or 0.9c is a mindless fantasy. Of course if you did not need to decelerate and you did not care about loss of life or material to explosion, i.e. you had a supernova mindset you could have some particles reach near the speed of light.

I will not even bother to see where are you wrong..
You need to imagine that the mass of the black hole is antimatter propellent, with few % of neutrinos.
50% of efficiency is achievable just as we discuss with K2, and in theory can be more.
In the paper said that a 600000 ton black hole can accelerate at 10% the speed of light in 20 days (160 petawatt), it will be 40 days at 50% efficiency and it will take 1 year to achieve 0.95c, this black hole only last 3,5 years, but due lorenz factor, it can complete the journey to proxima centauri way before drop it, but well that acceleration is too much for humans and the final deceleration will be even higher.

A better case for humans will be a spaceship with 500000 tons (which is super super huge if you use light materials), all powered by a proton size BH (the ultimate battery that convert bananas into E=mc2), but this time the black hole will have 900000 tons, its power output at beginning will be 70 PW and its life expectancy 13 years.
I will not made the math, but just using the other case as comparison we can estimate it will have a respectable acceleration at the beginning with close to 1 gee deceleration at the end. This ship also can achieve 0.9c if you let it or much more for a long trips.
If the interstellar medium would not be a problem, you could travel huge distances (even 150 Ly) in less than 13 years (local time) or something like that.
 

6 hours ago, PB666 said:

Here is a o.1 scale prototype of a generataional ship

Note that kerbal only allows to show so many kerbals so the 24 that are on this ship are not shown.

Each cell in the full scale mode has a 250 MW fusion reactor, the ISP is 2500000 (velocity = 25 million about 0.08c)

Each reactor is separated by 80 feet in a full scale model and each wall along the line between reactors is about 8 meters of titanium, the fins are for heat dissippation the bottom of the fins are passive liquid sodium photon drives, primary coolant to liquid sodium liqud gas phase water cooling system. The drive are VASIMR type drives. Hull is 10 cm thick titanium, the actual ship would have 500,000,000 units of propellant plus dueterium and hydrogen.

All that just for a crew capacity of 24? XD
Units of propellent?   How much in metric tons?
 

Quote

...........As you approach C the impactors atoms appear more massive, and so on impact they would have a tendency to do more damage.
Electrons create repulsion, so if the electrons do not have time to create charge density in front of the atom, you can look at the frequency of electrons is particular orbitals, ..................... and so on impact they would have a tendency to do more damage. So the atoms first line of defense is the electron shield this shield covers the crosssectional area of the atom as two atoms collide,........................... The next point of elasticity are the nuclei, the nuclei are essentially around 10E-15 across about 1/100000 the diameter of an atom, so its cross sectional area is 10E-10 of the entire atom. However, alpha particles do not have enough energy to penetrate to the center so the effective 1/1000000 the size of an atom from a scattering point of view. We can do some calculations, if we assume that a ship is going about 0.01C and an atom is about 10-10 thick, then how far does an atom have to travel before it is scattered by another atom.............................. ................................................Thin layering is not necessarily protective since solid/gas phase transition between the layers can cause them to separate and opening up huge areas to higher risk, just like a poly-wall tire that overheats due to stress and overheating. 

You wrote a lot....  somethings are very easy to resume not sure why you choice to make 6 lines that can be reduce in few words.
I dont have time to answer now, If I try to read all that and confirm some data will take me 1 hour at least.
You did not even wrote a conclusion.. which it will be much easier to answer just linking other papers in case I disagree.

3 hours ago, magnemoe said:

Ok so front shield get radioactive, note that this only affect the front you travel so fast you will not get anything from the side. 
This might be bad for stuff like solar sail or medusa. 
This will also create an issue for the forward thin shield.

An positive charge will deflect protons however I doubt it would be strong enough to deflect them at this speed? 

Solar sails are not affected, all the energy of incoming particles remains in the particle.. you just lost few atoms on the sail.

[K^2]

16 minutes ago, AngelLestat said:

Ok bad news, maybe I will save you some work.. I read the original paper from Crane on BH propulsion.
He said that if the black hole is charged or spinning, then it release its power much faster, (the second until its spinning stop) not sure why..
Also no sure why you said that only QED can explain it, the gravity in this case is enough strong to change things very differently at quantum distances..
In other words, 1000 attometers of difference in a big black hole means nothing, no change on gravity, but on a SBH there is a huge change.
So it will need quantum gravity?
Here's the original paper, is interesting.
http://arxiv.org/pdf/0908.1803.pdf

Paper doesn't suggest that charged BH will decay faster. Only that it will radiate the charge away. I'll have to find references on that to see how fast it's going to radiate charge. It might still be possible to maintain the charge with matter that's being constantly fed to the BH.

QED can be done in curved space-time. Relevant scale where you have to use Quantum Gravity is Plank Scale. Everything above it can be addressed with adequate theory. QED in vicinity of BH, but well above its event horizon is very well behaved.

[PB666]

10 hours ago, AngelLestat said:

Ok bad news, maybe I will save you some work.. I read the original paper from Crane on BH propulsion.
He said that if the black hole is charged or spinning, then it release its power much faster, (the second until its spinning stop) not sure why..
Also no sure why you said that only QED can explain it, the gravity in this case is enough strong to change things very differently at quantum distances..
In other words, 1000 attometers of difference in a big black hole means nothing, no change on gravity, but on a SBH there is a huge change.
So it will need quantum gravity?
Here's the original paper, is interesting.
http://arxiv.org/pdf/0908.1803.pdf
 

It was only to explain you how a thin and long ship might looks like... Also.. that ship was carefully designed for a scientist. 

 

I will not even bother to see where are you wrong..
You need to imagine that the mass of the black hole is antimatter propellent, with few % of neutrinos.
50% of efficiency is achievable just as we discuss with K2, and in theory can be more.
In the paper said that a 600000 ton black hole can accelerate at 10% the speed of light in 20 days (160 petawatt), it will be 40 days at 50% efficiency and it will take 1 year to achieve 0.95c, this black hole only last 3,5 years, but due lorenz factor, it can complete the journey to proxima centauri way before drop it, but well that acceleration is too much for humans and the final deceleration will be even higher.

A better case for humans will be a spaceship with 500000 tons (which is super super huge if you use light materials), all powered by a proton size BH (the ultimate battery that convert bananas into E=mc2), but this time the black hole will have 900000 tons, its power output at beginning will be 70 PW and its life expectancy 13 years.
I will not made the math, but just using the other case as comparison we can estimate it will have a respectable acceleration at the beginning with close to 1 gee deceleration at the end. This ship also can achieve 0.9c if you let it or much more for a long trips.
If the interstellar medium would not be a problem, you could travel huge distances (even 150 Ly) in less than 13 years (local time) or something like that.
 

All that just for a crew capacity of 24? XD
Units of propellent?   How much in metric tons?
 

You wrote a lot....  somethings are very easy to resume not sure why you choice to make 6 lines that can be reduce in few words.
I dont have time to answer now, If I try to read all that and confirm some data will take me 1 hour at least.
You did not even wrote a conclusion.. which it will be much easier to answer just linking other papers in case I disagree.

Solar sails are not affected, all the energy of incoming particles remains in the particle.. you just lost few atoms on the sail.

Well its a paper is must be true, ROFL. 0.95c is manure, strait off and without even looking at the paper. .

Correcting one error in what K2 said from the paper " Note: that if an isolated SBH is initially endowed with an electric charge, then it will quickly, and almost completely,radiate this charge away (see [3], p. 398)." So you can endow it with a charge but it won't keep it, so you cant use charge to accelerate it. Of course as we read on in the paper we find that this source of information is less than credible.

"A high-efficiency square solar panel a few hundred km on each side, in a circular orbit about the sun at a distance of 1,000,000 km, would absorb enough energy in a year to produce one such BH"
(the paper you idolize) Err....... unfortunately solar panels have to be tilted at sharp angles within 60,000,000 km of the sun, that would simply vaporize at that distance. At 150,000,000 km the sun produces 1.3 kW per meter of power, most panels if cooled in some fashion can handle up to 50kW per meter. The amount of power on panel a milion km from the sun is going to be 30375 kW per meter. that is roughly 600 times what a solar panel in atmosphere can tolerate, and many times more than a panel in space can tolerate. 

"A radius of 1 attometer corresponds to the wavelength of a gamma ray with an energy of about 1.24 TeV. Since the wavelength of the Hawking radiation is 8 π2 times the radius of the BH, the Hawking temperature of a BH with this radius is on the order of 16 GeV, within the limit of what we could hope to achieve technologically."  Errr....above 5 MeV gamma rays in close proximity result in pair production, this would cause scattering of the incident ray resulting in any beam used to create a black hole significantly scattering before reaching the center of the sphere.

"Now the idea that the wavelength of the radiation should match the radius of the BH created is very likely pessimistic." No duh. Aside from the fact that Heisenberg uncertainty inhibits the focusing of a beam of light to 1 attometer, that this has to be done all at the same moment, and that photons that get in close proximity prior to reaching the BH site are likely to undergo pair production and scatter . . . . .

"Although a laser-powered black hole generator presents huge engineering challenges, the concept appears to be physically sound according to classical general relativity. The Vaidya-Papapetrou metric shows that an imploding spherically symmetric shell of “null dust” can form a black hole" Oki-doki, this is what I call the classic psuedoscience if and if and if argument. Yes we have lasers, but no lasers that can produce 16GeV photons, 'technically impossible' unless that laser were traveling in the direction of the black hole at nearly light speed. In essence to seed a laser that produces such high wavelengths you need a nuclear decay that produces the photon and a similar material in the laser that can be excited, its hard to imagine a laser composed of materials that an electron decays from an excited state producing 16GeV, it has to be the result of nuclear decay. This is in the high energy gamma range, the types of energies produced by machines such as hadron colliders and are not generally possible in small compact equipment of the type required to create a spherical shell. Laser is the production of a beam of light from a column in which atoms are excited in unison, the beam has to be contained, which takes space and there has to be an energy source to excite, which means we have energy density and heat, which ultimately limiting the energy density of laser light created per unit space.

So if we assume that a black hole is being formed of 600,000,000 kg = E/c² therefore E = 5.4 x 10²⁵ joules. Now lets say that this all has to be done within a wavelength of 1 attometer. That is to say within t = 10^-18/3 x 10⁸ m/sec = 3.33 x 10^-26 seconds, therefore the E/sec = 1.62 x 10⁵¹KW. If we assume that a laser with a face of 10 cubic centimeters can maximally produce 1 KW (a very generous assumption) then we can produce .. . . Oh screw logic, lets just say they got to within a 1000th of the speed of light blue-shifting the lasers energy 1000 fold so that we have a MW per 10 cubic centimeter (that means these spaceships have a cross sectional face of 10 cm). OK so thats 1 x 10⁹ watt/m². That means we would need 1.62 x 10^(51-9) m² of laser production 1.62 x 10⁴² which translates to a sphere of 1.62 x 10⁴² = 4pi* r²  R = 3.59 x 10²⁰ meters, IOW our feild of lasers would have to be approximately 10000 ly (9.4607×10¹⁵ m) away when fired traveling at 0.999c. ROFLMAO. Huge engineering challenge is a very fluffy way of saying its about as likely as well god (insert benevolent alien race) giving us a black hole. So Angel have you bothered to even think what uncertainty is going to do with the theta of emitted photons at such distances, are they going to be +/- kilometers, 10s of kilometers, 100s of kilometers from their target? Lets say we can form a black hole over say a month, sure we reduce the shell but by how much you are still in the 10 x 10¹⁰ radius range, still not close enough to even get close to an attometer. The reality here is that 100 KeV nuclear laser needs to be moving toward the black hole at about 99,999c/100,000.

This paper just gets  better and better,  any one can publish anything in this journal, do the referees even know how to do arithmetic?

"Since a nuclear laser can convert on the order of 10^-3of its rest mass to radiation, we would need a lasing mass of order 10⁹ tonnes to produce the pulse. This should correspond to a mass of order 10¹⁰ tonnes for the whole structure (the size of a small asteroid)." Great but nuclear lasers produce hv in the KeV range, a million times lower than what they are proposing. Second an asteroid is a block of rock not necessarily radioactive (in fact very little radioactivity), and finally those lasers are going to have to be spread over a considerable area. If that 10¹³ kg is made into a shell, the thin shell is fed into the laser then that shell would occupy a very large area, remember the pulse has to be very fast and you cannot pulse a meter thickness of asteroid/fissile product through a nuclear laser. the amount of material fed into the laser would be on the order of pico to femtomoles of fissile material per pulse. https://en.wikipedia.org/wiki/Nuclear_pumped_laser - points out that the closest we have gotten to a X-ray laser is 21nm and relies on reaction based. The authors even get the materials wrong, you would not need solar cells and electric power so much as "Fusion lasers (reactor driven lasers) started testing after the bomb-driven lasers proved successful. While prohibitively expensive (estimated at 30,000 dollars per test)," you need fusion reactors, anyway

  "This is clearly extremely ambitious, but we do not see it as impossible." I think prolly everyone in that group needs to see an optometrist.

"The reader has no doubt by now observed that a great many questions in this proposal are left open." meaning hand waving to a solution that is technically impossible, and where is Angel's discussion of light speeds? This paper magically assumes that somehow we can

1. Convert 1/10000th of asteroid mass into 16GeV hv
2. Do it fast enough that the black does not radiate itself into non existence moments after we lase it.
3. That it is possible to coordinate the pulsing of focused a tremendous scale of laser light to one attometer at a rather great distances.
4. That we can make powerful sub nano-meter wavelength lasers.

"We can mention the self-focusing of a focusing electromagnetic wave, and the possible effects of gravitational lensing and magnification on the various aspects of our problem" How exactly is that going to work and coordinate over the vast expanses of space at human capable EM production densities. If you want highly refined directed laser light in the 10 to 1KW range fine, but the authors are asking about energy production in the TW/laser range if not higher. Humans have no ability to produce that density of light let alone high energy gamma and certainly no refined ability to focus it at those power outputs. If and If and If . . . . . .

BTW, producing a black hole close to earth with 16 GeV, and the amount of energy they suggest, think a sterilized earth (unless you are cave dweller or deep sea inhabitant)

But no where in this paper does it suggest reaching 0.1c in 20 days or reaching a speed of 0.95c.

 

10 hours ago, K^2 said:

Paper doesn't suggest that charged BH will decay faster. Only that it will radiate the charge away. I'll have to find references on that to see how fast it's going to radiate charge. It might still be possible to maintain the charge with matter that's being constantly fed to the BH.

QED can be done in curved space-time. Relevant scale where you have to use Quantum Gravity is Plank Scale. Everything above it can be addressed with adequate theory. QED in vicinity of BH, but well above its event horizon is very well behaved.

They say it loses charge rapidly, but I find the remainder of their work handwaving incredulity.

The most essential bit of information they did not provide, timing. First, what is the minimum sized radius that they can produce, if their limit is 16 GeV then a smaller radius would not absorbe all of the radiation (even if they could target it) and thus to form a black hole they would have to feed all of 16 GeV at that space at once. If they could feed TeV they might be able to pulse the black hole over a month or so to form it. But what is the limit? How small can a black hole be and how long would it last, if you could pulse say a million times a second would a millionth of a second the black hole decay.  Integral R_o to 0, c^4.R²/ 2^.G^.a^.F(t) dR  c = speed of light, R = black hole radius, G = universal gravitational contant, a is their constant, apparent the published value of 10^-22 was to low so they are using 10^-20 F(t) = function (time) of all the various energy particles produced use 100.

Based on this equation you could have a BH of size 10^-21 stable for a millionth of a second but to build it you would need to pulse it with 16TeV at say 1/1000000 the of the total energy required but in a smaller area, even at millionth of that energy they are still looking at targeting the black hole from a distance of 10 ly, which is nearly impossible.

 

 

Edited February 19, 2016 by PB666

[fredinno]

On February 17, 2016 at 1:10 PM, PB666 said:

First, I don't use movies as a judge of what is and what is not possible, and second with regard to your physicist claim that is at 0.8 or 0.9c, since we do not have a method of reaching that velocity we have to consider the potency to catastrophic impacts at lower speeds.

If we ignore reaction mass, the very best you can do (c2/2) = 0.707c, That is not accounting for the mass on board to slow the ship down. The BH drive is producing EM which generations N per 300MJ of Energy. If the wormhole is initially 1/2 the ships weight, and E = mc2 the 0.5*9E16 = 4.5E16 joules. The average accel mass is ~0.8 and average decel mass is 0.6 which means we use  2.6E16J per starting ship mass on accel leg and 1.9 on the decel leg. Therefore on the accel leg you can produce 86666667N per starting mass over and average relative to starting mass of 0.8 which ends up begin 108333333 or 0.36C and deceleration at 105555556 0.35C. That assumes that all radiation is perfectly radiated backwards behind the ship. Assuming the perfect angle is theta and the average radiation vector is 45' then the cosine of 45 is the efficiency which at 0.707 is going to set that theoretical maximum at 0.25c. Some of the radiation will be used by the ship, and wasted. Also as the blackhole shrinks it eventually becomes unstable and has to be ejected, so at best you are probably looking at 0.2c. 0.8 or 0.9c is a mindless fantasy. Of course if you did not need to decelerate and you did not care about loss of life or material to explosion, i.e. you had a supernova mindset you could have some particles reach near the speed of light.

 

Well, that's one place Alcubierre Drives could initially be used for (STL is eaiser than FTL for those drives.)

[PB666]

OK so by tweaking several factors, I managed to get my FEP interstellar to get to 45  years accelerating to 0.006 c, this would take 666 years to reach proxima centauri adding an additional 45 years to accelerate and decelerate to full speed. Its peak speed of 1.75 million is close to limit of IS risk. In this vessel 1/4th of the mass is fuel (the vessel mass was increased to 2 million tonnes) but I now only need to take around 200 individuals on board. I still think this is too fast for safe interstellar space travel. ISPg = 1250000 sec (Xenon needs to be ejected at 12,400,000 m/s) The vessel produces 2kN of thrust but this is devided across 2000 starting tonnes. The equation 2000 = 2 * k_eff * Power / specific impulse velocity  then Power = 1000 * 12400000 = 12.4 GW of power divided by 45 reactors is 276 MW per 10 meter fusion reactor.

[PROBLEM #1]. Right so that the power density I was using for each reactor is actually a major handwave at fusion, 276MW per 10 diameter reactor is probably a far reach, originally I used 100MW which seamed more reasonable. [JUXT] But in shrinking my ship to one tenth scale I forgot to shrink power to 1/1000th of the original so now my FR are producing at 2760 a sensible power density. I should have used a full sized reactor, which is fine, but it means the unit cell is larger, which means I can put fewer reactors back there instead of 45 its more going to be like 15 cutting power output to 1/3rd. Ok so the trip takes 2100 years. [Massive] 15 reactors weighing 50 tonnes each, that is 750 tonnes so I need to increase also the weight of my ship by 700 from 2000 to 2700 this further extends our trip and the number of inhabitants. Adding bulk to the back of the ship allows the 30 addition reactors to be added, but at the cost of 1400 tonnes so we can get our ship now double in mass and down to 1400  years. 

Now for he handwaving parts.
1. I am assuming 100% efficiency on all electrical processes, it is unclear how efficient an 12400000 ISP would be
2. right now the practical power density for ION drives is around 100kW per meter, this means that in order to generate this amount of thrust I would need 124000 square meters a backward facing surface, this is much more than my pi^.32² = 3216 m²  ship back provide and probably requires much larger radiator fins. On a ship 10 times the size theproblem is considerably worse, much more fin would be needed. 
3. the 45 @ 276 MW reactors would have to either produce 1000 times more power per unit or I would need a 1000 times more of them. If they are spread 80 m apart occupying a space of 1600 m² each then I would need to get them to occupy at least 1.6 m² each which is impossible, so that the fins would have to have both fusion reactors and ion drives on them.
4. All those are managable issues to some degree (compared to FTL or BH drives), this is where the hands wave

Nucelar fission releases 4.2 MeV of energy per 4 atomic units (2 deuterium).  So we have several ION drives solely devoted to the acceleration of helium-4. So this is not a problem, and we can partition are fuel tanks so that some do not hold xenon but hold dueterium or hydrogen or neutrons, whatever.
[PROBLEM #2] the deuterium is about 3600 MeV of energy and if we are only getting 4.2 out then we are only getting 0.1% of the total energy within the deuterium. Lets say that 20% of the fuel is Dueterium (obviously we can breed deuterium with Neutrons released), that means we have on board 100,000 kg of deuterium gas. If then 0.1% of that is energy then its 100kg.

100*c² = 9 x 10¹⁸ J, OK so spread over the 162 years to accelerate/decelerate that amounts to 0.176 GW of power, ouch, well OK we simply remove xenon and replace it with deuterium (we have super new tanks and we can pressurize D into a solid of amazing density). So increasing D by 5 then gets us up to 8.8GW, OK so we need more fuel. 704.505 should do in a perfect world. But we have to reduce the rest of the ships mass. Since we are traveling faster we need fewer humans.

OK so where did I finally end up. Ship 320 meters (800 m) in radius about 640 meters (800m) in height, speed =  0.003 c, time to proxima 1400 years. Number of colonizers 400. Starting ship Mass 4000000000 kg (4 million tonnes), Fuel mass 704,505 tonnes (majically stored deuterium), Power output 12.4 TW, spread over 45,000 [wheezing] 0.000276 TW fusion reactors. Note I did not add any additional energy for our unlucky humans (who will spend all their lives a few hundred meters from neutron heaven), that is because when we increased the fuel we can lower the ISP to 890000 and decreasing the power needed for drive. Percent of ship devoted to Fusion reactors and cooling, about 70%, percent devoted to fuel (starting) 17%, percent of fuel mass remaining 13% for superstructure and humans.

Unfortunately the dimensions of the ship are two big for the launch pad so  . . . . . . . .

 

 

[AngelLestat]

On 19/2/2016 at 10:36 PM, K^2 said:

Paper doesn't suggest that charged BH will decay faster. Only that it will radiate the charge away. I'll have to find references on that to see how fast it's going to radiate charge. It might still be possible to maintain the charge with matter that's being constantly fed to the BH.

QED can be done in curved space-time. Relevant scale where you have to use Quantum Gravity is Plank Scale. Everything above it can be addressed with adequate theory. QED in vicinity of BH, but well above its event horizon is very well behaved.

Ok my bad.. Not sure why understood the spin in that way but no the charge.
 

On 19/2/2016 at 0:14 AM, PB666 said:

Well its a paper is must be true, ROFL. 0.95c is manure, strait off and without even looking at the paper. .

Let me start repeating that I dont defend any long tech, I always said that interstellar manned missions are way far of our reach in practical terms.
But I dont have any trouble discussing interstellar probes because I know a possible cheap and practical way.
I just joint up to the BH ship because is fun to think about it, and find ways to focus that energy that I did not thought before. 
Use the search tool in the forum, and put my name and search by black hole propulsion, or SBH.  I comment on this since 2013 and I always knew how hard it was.  But you are mad that everybody point you the big error of your 50000 years trip and now you are trying to search anything to criticize.

On 19/2/2016 at 0:14 AM, PB666 said:

"A high-efficiency square solar panel a few hundred km on each side, in a circular orbit about the sun at a distance of 1,000,000 km, would absorb enough energy in a year to produce one such BH"............

This paper just gets  better and better,  any one can publish anything in this journal, do the referees even know how to do arithmetic?

That is not a concern.. the real concern is how you storage all the energy you need to then be used in 1 nano or pico second all focus in something very small..
The same author recognizes how hard is to make a SBH, but the true is that there is nothing in physics that said that is no possible.
So he just let away with the possibility without boring the reader on engineering details of how to achieve that, why?   because is a conceptualized notion of an original idea.  Just that.  The idea is that you can use black holes for propulsion, something that nobody thought before.. so more respect to the author!
That is why he also mention the super lucky chance of find one by accident.
But well, at least he was bother to put some "details" on how can be one created... Try to find some details in ZPE or FTL ships.

On 19/2/2016 at 0:14 AM, PB666 said:

"The reader has no doubt by now observed that a great many questions in this proposal are left open." meaning hand waving to a solution that is technically impossible, and where is Angel's discussion of light speeds? This paper magically assumes that somehow we can

1. Convert 1/10000th of asteroid mass into 16GeV hv

Asteroid??  what asteroid?
BTW, is incredible the amount of time you waste trying to point obvious issues for the practical BH creation when nobody was defending the idea or even commenting on that matter.
And yes.. if we have one black hole.. then is possible in the long term to build a ship and use it to reach lightspeeds, I show you how in that case you can achieve light speed with 50% of efficiency or even less (when you said that was impossible).
But now after so incredible long post.. you did not said nothing about that..  how is that possible?
 

On 19/2/2016 at 11:49 AM, PB666 said:

OK so by tweaking several factors, I managed to get my FEP interstellar to get to 45  years accelerating to 0.006 c, this would take 666 years to reach proxima centauri adding an additional 45 years to accelerate and decelerate to full speed. Its peak speed of 1.75 million is close to limit of IS risk. In this vessel 1/4th of the mass is fuel (the vessel mass was increased to 2 million tonnes) but I now only need to take around 200 individuals on board. I still think this is too fast for safe interstellar space travel. ISPg = 1250000 sec (Xenon needs to be ejected at 12,400,000 m/s) The vessel produces 2kN of thrust but this is devided across 2000 starting tonnes. The equation 2000 = 2 * k_eff * Power / specific impulse velocity  then Power = 1000 * 12400000 = 12.4 GW of power divided by 45 reactors is 276 MW per 10 meter fusion reactor.

750 years of travel..  Those are 30 generations..  How you keep them alive?  With a machine that can take any atom and convert that to other atoms and 3d print any object they want?
How you solve all the social issues over 750 years?
How much take this ship to be made?   What kind of tech appear in that time? Just an small increase in efficiency in your engines due tech, it will save 50 years at least, which is enough reason to always wait a bit longer before made it.
More if you want to try a 750 year experiment with 200 dead guys (or grandchildren if you are lucky) 
So time ago I did a big post proving with logic and ton of evidence..  that we are close to make an IA (15, 30, or 60 years, does not matter), and this IA once created evolves exponentially, this mean that in few years, lets said 50 more, it will reach GOD status, this mean that it will know everything that can be know in the universe (you just need a big of logic and common sense to prove that).
That is just a little example of how huge can be your error of just ignore the effect of technology evolution over 750 years. 

On 19/2/2016 at 11:49 AM, PB666 said:

[PROBLEM #1]. Right so that the power density I was using for each reactor is actually a major handwave at fusion, 276MW per 10 diameter reactor is probably a far reach, originally I used 100MW which seamed more reasonable. [JUXT] But in shrinking my ship to one tenth scale I forgot to shrink power to 1/1000th of the original so now my FR are producing at 2760 a sensible power density. I should have used a full sized reactor, which is fine, but it means the unit cell is larger, which means I can put fewer reactors back there instead of 45 its more going to be like 15 cutting power output to 1/3rd. Ok so the trip takes 2100 years. [Massive] 15 reactors weighing 50 tonnes each, that is 750 tonnes so I need to increase also the weight of my ship by 700 from 2000 to 2700 this further extends our trip and the number of inhabitants. Adding bulk to the back of the ship allows the 30 addition reactors to be added, but at the cost of 1400 tonnes so we can get our ship now double in mass and down to 1400  years. 

Now for he handwaving parts.
1. I am assuming 100% efficiency on all electrical processes, it is unclear how efficient an 12400000 ISP would be
2. right now the practical power density for ION drives is around 100kW per meter, this means that in order to generate this amount of thrust I would need 124000 square meters a backward facing surface, this is much more than my pi^.32² = 3216 m²  ship back provide and probably requires much larger radiator fins. On a ship 10 times the size theproblem is considerably worse, much more fin would be needed. 
3. the 45 @ 276 MW reactors would have to either produce 1000 times more power per unit or I would need a 1000 times more of them. If they are spread 80 m apart occupying a space of 1600 m² each then I would need to get them to occupy at least 1.6 m² each which is impossible, so that the fins would have to have both fusion reactors and ion drives on them.
4. All those are managable issues to some degree (compared to FTL or BH drives), this is where the hands wave

Nucelar fission releases 4.2 MeV of energy per 4 atomic units (2 deuterium).  So we have several ION drives solely devoted to the acceleration of helium-4. So this is not a problem, and we can partition are fuel tanks so that some do not hold xenon but hold dueterium or hydrogen or neutrons, whatever.
[PROBLEM #2] the deuterium is about 3600 MeV of energy and if we are only getting 4.2 out then we are only getting 0.1% of the total energy within the deuterium. Lets say that 20% of the fuel is Dueterium (obviously we can breed deuterium with Neutrons released), that means we have on board 100,000 kg of deuterium gas. If then 0.1% of that is energy then its 100kg.

100*c² = 9 x 10¹⁸ J, OK so spread over the 162 years to accelerate/decelerate that amounts to 0.176 GW of power, ouch, well OK we simply remove xenon and replace it with deuterium (we have super new tanks and we can pressurize D into a solid of amazing density). So increasing D by 5 then gets us up to 8.8GW, OK so we need more fuel. 704.505 should do in a perfect world. But we have to reduce the rest of the ships mass. Since we are traveling faster we need fewer humans.

OK so where did I finally end up. Ship 320 meters (800 m) in radius about 640 meters (800m) in height, speed =  0.003 c, time to proxima 1400 years. Number of colonizers 400. Starting ship Mass 4000000000 kg (4 million tonnes), Fuel mass 704,505 tonnes (majically stored deuterium), Power output 12.4 TW, spread over 45,000 [wheezing] 0.000276 TW fusion reactors. Note I did not add any additional energy for our unlucky humans (who will spend all their lives a few hundred meters from neutron heaven), that is because when we increased the fuel we can lower the ISP to 890000 and decreasing the power needed for drive. Percent of ship devoted to Fusion reactors and cooling, about 70%, percent devoted to fuel (starting) 17%, percent of fuel mass remaining 13% for superstructure and humans.

Unfortunately the dimensions of the ship are two big for the launch pad so  . . . . . . . .

Ok.  now your colonizers number increase, your travel time double, its crear that you dont see any problem with that last...
Forgetting that crazy factor..  yeah the ship design seems fine.
But I see wrong some things..  you dont have stages to release cargo that you would not need. Something that any rocket should have, more if you want to cross interstellar distances.
I will use lower number of nuclear reactors (which reduce weight) and increase the acceleration time that is very small compared to the trip % without acceleration.

[PB666]

3 hours ago, AngelLestat said:

Ok my bad.. Not sure why understood the spin in that way but no the charge.
 

Let me start repeating that I dont defend any long tech, I always said that interstellar manned missions are way far of our reach in practical terms.
But I dont have any trouble discussing interstellar probes because I know a possible cheap and practical way.
I just joint up to the BH ship because is fun to think about it, and find ways to focus that energy that I did not thought before. 
Use the search tool in the forum, and put my name and search by black hole propulsion, or SBH.  I comment on this since 2013 and I always knew how hard it was.  But you are mad that everybody point you the big error of your 50000 years trip and now you are trying to search anything to criticize.

That is not a concern.. the real concern is how you storage all the energy you need to then be used in 1 nano or pico second all focus in something very small..
The same author recognizes how hard is to make a SBH, but the true is that there is nothing in physics that said that is no possible.
So he just let away with the possibility without boring the reader on engineering details of how to achieve that, why?   because is a conceptualized notion of an original idea.  Just that.  The idea is that you can use black holes for propulsion, something that nobody thought before.. so more respect to the author!
That is why he also mention the super lucky chance of find one by accident.
But well, at least he was bother to put some "details" on how can be one created... Try to find some details in ZPE or FTL ships.

Asteroid??  what asteroid?
BTW, is incredible the amount of time you waste trying to point obvious issues for the practical BH creation when nobody was defending the idea or even commenting on that matter.
And yes.. if we have one black hole.. then is possible in the long term to build a ship and use it to reach lightspeeds, I show you how in that case you can achieve light speed with 50% of efficiency or even less (when you said that was impossible).
But now after so incredible long post.. you did not said nothing about that..  how is that possible?
 

750 years of travel..  Those are 30 generations..  How you keep them alive?  With a machine that can take any atom and convert that to other atoms and 3d print any object they want?
How you solve all the social issues over 750 years?
How much take this ship to be made?   What kind of tech appear in that time? Just an small increase in efficiency in your engines due tech, it will save 50 years at least, which is enough reason to always wait a bit longer before made it.
More if you want to try a 750 year experiment with 200 dead guys (or grandchildren if you are lucky) 
So time ago I did a big post proving with logic and ton of evidence..  that we are close to make an IA (15, 30, or 60 years, does not matter), and this IA once created evolves exponentially, this mean that in few years, lets said 50 more, it will reach GOD status, this mean that it will know everything that can be know in the universe (you just need a big of logic and common sense to prove that).
That is just a little example of how huge can be your error of just ignore the effect of technology evolution over 750 years. 

Ok.  now your colonizers number increase, your travel time double, its crear that you dont see any problem with that last...
Forgetting that crazy factor..  yeah the ship design seems fine.
But I see wrong some things..  you dont have stages to release cargo that you would not need. Something that any rocket should have, more if you want to cross interstellar distances.
I will use lower number of nuclear reactors (which reduce weight) and increase the acceleration time that is very small compared to the trip % without acceleration.

My biggest concern is not keeping them alive, humans have gooten way better a self contained systenms, its way ahead of fusion, we are getting close to the point that we have a dirty laundry list of bacteria that we need to complete a system, so given space, a couple of wavelengths of light, a machinecthat can make leds and its doable. The black hole drive and fusion have a common problem radioactivity and diwnstream particles like neutrons, also increasing velocity makes cosmic rays coming from the bow all the more dangerous. 

In terms of the BHD, the really important point is spatial density, i consider it impossible if you have to move so far from the center to fire that space time phenomena obviate precision targeting, In this case both quantum and relativistic phenomena augment each others effects. Its impossible to create. 

 

[magnemoe]

13 hours ago, PB666 said:

My biggest concern is not keeping them alive, humans have gooten way better a self contained systenms, its way ahead of fusion, we are getting close to the point that we have a dirty laundry list of bacteria that we need to complete a system, so given space, a couple of wavelengths of light, a machinecthat can make leds and its doable. The black hole drive and fusion have a common problem radioactivity and diwnstream particles like neutrons, also increasing velocity makes cosmic rays coming from the bow all the more dangerous. 

In terms of the BHD, the really important point is spatial density, i consider it impossible if you have to move so far from the center to fire that space time phenomena obviate precision targeting, In this case both quantum and relativistic phenomena augment each others effects. Its impossible to create. 

 

Agree here on self contained systems. Problem will be having them and ship run for thousands of years. You must be able to rebuild pretty much any part of your ship making it an von-neuman machine, yes humans would supply the intelligence and repair capacity but you still need to be able to build anything from integrated circuits to nuclear reactors. 

Also why use an black hole drive then going slow. I would use orion, it scales very well for huge ships like this will be and is easy to low tech, good fusion has better isp but might be hard to scale up and is harder to repair. 
The black hole drive is more like bussard ramjet hard. 

[PB666]

How fast can a black hole drive be.

First we have to define the setup
1. We have a load, lets say the load is 1/3rd of the total vehicle its nature does not matter, the only quality of load that we care about is that any hv or particles traveling in the -y direction are either reflected or emmitted in the xz, that is no hv or particles travel with a velocity vector relative to the ship of -y.

2. We have a device which defines the power plant of the ship. It performs several functions
a. I positions the black hole (how this can be done is beyond the scope of this presentation)
b. It reflects the black holes radiation
c. It insulates the ship from the black holes radiation
d. It transmits non-inertial forces from the back of the ship to the payload
e. It wastes energy by allowing some hv to escape in the xz directions.

The amount of waste energy is defined as the Power vectors xz that is to say the accumulation of all radiant vectors (sqrt(Sq(TotalPower)+sq(Power-y)). The blackholes radiation vectors present as a shere of power, its essentially powerdensity at 1 meter radius. If we then take the Y (thrust vector) and ignore -y that comes to about 27%, the -y has to be dealt with separately. For all vectors that have a +y component about 23% have energy that is wasted. If we forget about acceleration and set the reference frame of the powerplant, and set the blackhole as a point light source. The further the the mean distance of the surfaces relative to the source, and the smaller their profile, the less light will be reflected

Case 1 is microscopic efficiency.
In this case the power plant is far behind the source, the red dot in the image is off to the right, only a few photons strike the power plant and the force exherted on the device is almost zero. since the -y and y vector component of photon bearing cancel each other out the net efficiency is zero.  

Case 2. wide flat perfectly reflective surface. About half the photons are reflect off the surface, the other half radiate into space. Assuming the origin to be the center of the source basically we can determine these X2 + y2 + Z2 = 1 and this can be used to determine the proportion of y vector and not-y vector. the mean y vector is ~.55, it can be split into -y and y, y radiates into space and -y reflects and radiates in the y direction. In this case the amount of waste is 1 - 0.55 or about 45%

Case 3. We have a wide flat perfectly opaque surface. In this case half of the 0.55 or about .275 component is in the y direction.
the -y directed photons are perfectly absorbed by the power plant, some are radiated backwards and some are radiated to the side.

Case 4. I we have a hyperbolic mirror that reflects the photons in which case we can convert all the directions to y and this is 100%

Dealing with -y photons.

So basically the types of photons that the black hole is emitting is the high energy stuff, we can't see it. IN fact the frequency of radiation in a 1 attometer black hole is in the TeV range, which is well about the gamma for more radioactive decay.
https://www.physicsforums.com/threads/reflecting-gamma-rays.515289/. These photons will be absorbed, and on absorption they impart much of their momentum, however they will also generate radiant heat which will dissipate in many directions.

So basically we can think of a black hole devise as case number 3, our minimun efficiency is 0.275, and we can assume that we can get 0.25 by absorbption, but the remainder depends on how heat is channeled through the power plant. As I progress through the post we can see that this is not completely subject to theoretical. Just like creating a black hole, redirection -y momentum is full of technical challenges that may not be solvable, at least not for a bh of the 1 attometer - 0.01 attometer size range).

Creating as Filght

Lets be generous and say that we get 66% efficiency. Not withstanding that a blackhole will eventually blow up into a gamma-ray burst of immense power, we are going to assume that its power output is constant. But this is not true and the only real measure of energy available is via mass energy equivelance.

Next thing we need to do is plan our trip. Most trips will involve starting and stopping. Rarely would you just happen to accelerated to catch a planet that just happened to be whizzing by the sun at 0.Xc (x = your dV potential, lorentz transformed of course), but anyway lets see what X might be, lets suppose that a black hole has is half the weight of a 1212000000kg ship, to keep it simple our unit is 1u = 606000 tonnes.

so ship weighs 1 and black hole weighs 1. Over the course of the journey it burns its weight, and we found a way to keep it from exploding and blowing us to smitherines. 1 unit is 606000000 x c² = 5.545E23 joules, since we are 66% efficient then we can produce how many newtons? 5.54E23 * 0.66/ c, so essentially is mass x c times * efficiency = 1.2 x 10¹⁷ N since we are not losing most of our mass we can sloppily set the mass at 1.5u and divide to get dV. In this case dV = 1.32 x 10⁸ which when divided by c  =  0.44C (more like 0.42c because of dilation)

How can we be confident in our results. We know how much energy is there, the mass energy equivilence tells us that E = mass * square of speed of light, we can't ever have more than that we know that momentum imparted on the ship is going to be roughly equivilent to that. We can get the number up, but then we have to get rid of some of both power plant and payload.

A stop and start flight

So next we want to stop and start. Basically SM/MidMass = MidMass/EM MidMass = 0.707 Starting Mass. Therefore we burn 0.586u over an sloppy average mass of 1.707u this means that we can reach a speed of 1.03 x 10⁸ m/s or 0.34c

So that is a rational examination of speed, given of course an irrationally produced black hole, a handwaving procedure for grapling it and accelerating it in step with the ship.  

The fairy-tail flight (the interstellar equivalent of 39 days to Mars and back again)

So lets now say that we created completely non-massive energy beings and our power-plants is crafted from a new material (Otherwise known as wee fairy-dust) that has stronger bonds than carbon and is lighter than hydrogen it perfectly reflects any em, no matter how powerful and its equally good at reflecting cosmic radiation and other unexpected black hole emissions. . In this scenario we cut our ship down now to 0.1u and the black hole 1, total weight is 1.1, the efficiency remains the same. 0.66%

So our new equation has 1.2 10¹⁷ N but now we have to get the weight, we can use the rocket equation.
This is a twist, take mass lost (606 kilotonnes) and devide by Newtons/dMass = 1.98 x 10⁸ which just happens to be c * our efficiency (imagine that). If we then go back and use this we find out that our maximum speed here is ln(11)*0.66c = 1.54c.
With speed above 0.5c one needs to do a transformation resulting 0.84c. http://math.ucr.edu/home/baez/physics/Relativity/SR/Rocket/rocket.html

Wee fairy-dusted start stop trip
 
1.1/midmass =  midmass/0.1 This tells us that we can burn down to about 0.33 during the acceleration phase, that is a change of 0.77u or 4.668E8 Mass. we can get our friend the equivilancy equation and the photon/force equivilancy to give us the total number of unwasted Newtons, 9.26E16N. With this we can calculate the acceleration phase to be 0.62c.

So this is strictly theoretical, however a starting Load + Powerplant(w/o BH has theoretical limitations)

Reality of the powerplant.

One of the problems is this. If we recall that particles tend to be stimulated according their frequency, and everything has a frequency. It is call the Compton wavelength. Why am I bring this up, it has to do with reflection. When we see light reflected from a mirror the reflected light is almost perfectly redirected, thus it is an elastic process. Light can be reflected, including UV and X-rays to some degree. But this is not true for high energy X-rays, gamma rays and particularly high energy gamma rays. As stated above the size of the black hole is directly proportional to its mass (the black hole being the sphere is space were no light can escape). A .9E-18 BH therefore has a wavelength, and the particles emmitted would also have a wavelength. Over the course of our trip our black hole is converting mass to ever shorter wavelengths. The low limit is 16GeV and would rise to the TeV range before a catastrophic loss of the hole. m = h/wavelength * c. So if the average wavelength is say 0.45E-18*2*pi = 2.9E-18, so this has a mass range it would like to dance with, around 8 x 10-25 kg. Protons have a mass of 1.67E10−27 kg. So basically this gamma can kick the butt of anything with atomic weight of 267, essentially it would knock these particles up to c. But this would not happen in the metal of the power plant, because it would obliterate the surrounding structures.

One of the arguments could be, well we simply use light atoms like aluminum, and the wavelengths just zip right through. OK if hv zips right through unaffected, you basically sacrifice your thrust, because without reflection or scattering, the -y and y vectors cancel each other out. So it is a requirement of the Powerplant that it must absorb or reflect, since no known material reflects these high energy things then is must absorb bh hv. So if it is absorbing it also means that the nuclei within are being scattered as they scatter this light. And overriding principle of any thruster is that we should not tabulate values of thrust associated with the destruction of the craft, this makes both of the above scenarios acceptable as a valid powerplant and thruster. Simply stated there is no certainty that these would survive until a full deceleration occurred, in which case if the power plant fails, then all the payload is essentially wasted. Therefore to make this work we have to split the powerplant into its superstructure and its ablator

So how big should the ablator be?

So we have the issue that the BH is shooting >50% of its energy at a structure that is designed to protect the material in front of it, primarily absorbing that mass, but in the process sacrificing itself as ejecta. Lets say they are ejecting the matter on the back of the ablater at 0.46c and that this accounts for 25% of the Energy of the BH. 0.25 * c² = 1.36 x 10²⁵ joules
1.36 x 10²⁵ = 1/2 X (1.5 x 10⁸)² that comes to a mass of 1.2 x 10⁹ so basically our powerplant needs to be twice the size of our black hole. And if we want (need) in the end that there be some mass to protect the payload, then the powerplant needs to be some safety factor larger, consequently that mass should be >2.2 times the size of the blackhole. In addition we want to steer those particles which means it should have shape, this means that shape will also have mass.  

If we go by this u (BH) + 2.5u(P) + 0.5u(L) = 4u. This complicates our thrust argument, we know we have 25% efficiency, but now what is thrust, this has to change in flight because the ability of the power plant to absorb and redirect heat changes with the ablation of the powerplant. The ablation of the powerplant increases as the black hole shrinks. We know we cannot reflect hv anymore, and we have much less ability to control radiation and limited ability to direct ablation.
If we assume the flat plat position the we have a given efficiency of 27%, and then we can add maybe another 25% in the form of ejected mass, which has momentum and can accelerate. I won't add this together, but I can reduce the mass separately. In addition at 0.1u the black hole is unmanagable and is ejected.
To do this we are going to break the trip up into 4 legs. So lets say that for each amount of energy 0.52% we eject 3.0u of mass during the course. So basically ISPv = 0.52 * c * ln(4/1.1) = 0.68c (not transformed) which means for each leg we have 0.34c. This another thing to be considered, if the output of the black hole is 3.5 years then its acceleration is going to be g/year * total dV/life = 0.194g or 1.96 meters per second. So in this model a trip = 2*1/2at² = 1.96 * (1.75 years) = 1.6 light years, and you did not make the trip to centauri, instead you have created a brand spanking new graveyard in interstellar space. Maybe Nemesis will rescue you.

Bottom Line

The bottom line is this, we have done several methods, starting with a simple model, then tested a fairy-tail model, and then finally a model compensated for the destructive forces of the drive. With the exception of the fairy-tail model, all models come in below 0.5c, the last model may not go far enough, since the full potential of the wormhole might not be available, and, in fact 606 kilotonnes for the bh may be too small and too unstable. I final and most important factor is this, acceleration. The problem here is that the black hole dies over 3.5 years as claimed the ship is accelerating to 0.39c which means its average speed is 0.2c across the duration of the trip. Then its not going to get there in 3.5 years but E-AC 4ly/0.2 = 20 years. Therefore the black hole is way too small, it needs to be larger. This is good because larger means less destructive radiation, but it also means more mass and slower acceleration. Its more or less the dog chasing its tail. If you get the black hole big enough that it only emits X-rays then you can perfectly reflect the radiation and efficiency goes close to 95%. How big is an X-ray black hole. So lets say we use 20KeV instead of 20GeV, in this case we have a radius 1000 times as large and a mass also 1000 times as large. Now our ablater can be rather small in size but we are now carrying around 250 times the load. The good news is that acceleration is constant and we can make a return trip, the bad news is that we would better off with fusion power.

A critical arguement here is going for smallest possible black hole is not so smart becaues weight of ablater needs to be added, going for a bigger black hole is not smart because acceleration goes down. Generation ships are the way to go.

We can go so fast that space dust will not matter?

First, invent fairy-dust, then we will talk.