We have escaped the galactic government, and now our greatest endeavour yet, life in space. How shall these gargantuan space entities move and travel through space?
- Surviving the vacuum. Insects have exoskeletons which already make them more resistant to having their inner fluids boil away into the vacuum (as seen in this video, where a spider and a fly survive a sojurn through the vacuum.
By luck these researchers found that if the exoskeleton is treated with an electron beam it makes a whole variety of insects more vacuum resistant. They called it a nanosuit exoskeleton.
Normally, if you put an insect in a vacuum, it dies. Its bodily fluids are rapidly sucked out of its body, which then collapses inwards into a crumpled husk. This is why SEMs are used on already dead specimens, which have been specially preserved. But Takahiko Hariyama from Hamamatsu University School of Medicine found that fruit fly maggots can survive these harsh conditions.
Bizarrely, Hariyama found that the microscope’s electron beam was somehow protecting the maggots. Indeed, if he turned the beam off before putting the insects in the vacuum chamber, their bodies crumpled in the usual horrific way.
Hariyama’s hunch was that the energetic electrons fuse molecules in the larvae’s cuticle (its outer layer) into a defensive coating, creating a hard but flexible barrier over their bodies. This barrier is just 50 to 100 nanometres (billionths of a metre) thick, but it’s enough to stop gases and liquids from leaving the larva’s body. ... This technique protected ants, mosquito larvae, honeybees, and fly maggots in an SEM’s vacuum chamber. It even worked on a soft-bodied flatworm. The animals survived their experience, and most of the mosquito larvae even transformed into adults later.
This is what the space whales have too.
Onboard oxygen supply. There is nothing to breathe in space. Neither is there anything underwater and so this tactic comes right from the real life whale repertoire. Whales use a hemoglobin-like molecule called myoglobin to store huge amounts of oxygen, sustaining them for their deep dives. Your space whales will have even more myoglobin - grossy obese with huge internal lakes of it - to sustain them on their travels through the void. Exhausted myoglobin can then be metabolized for energy.
Heat loss. Things that make internal heat (like machines, or these exothermic space whales) get hot in space. It is a problem. The only way to get rid of heat is to radiate it away: without surrounding matter convection and conduction are not options. Or: you can concentrate your heat in dispensible matter and jettison the matter with the heat. This is what the whales do, with metabolic products and waste. Which leads us to
Propulsion. Every action has an equal and opposite reaction. To move forward while floating in space, you must throw matter behind you. This the whales do, expelling hot wastes (maybe heated to gaseous state) for jet propulsion.
I am pondering whether a gas vortex would be possible in space - I am thinking of those smoke vortex cannons in which the expelled smoke rings hold themselves together for a distance. If one can make a gas vortex in space then these whales definitely will be doing that. For communication purposes, of course; in space, no-one can hear you sing.
How do space whales move? With great difficulty is the simple answer. The medium of space is too low density for an astrocetacean to swim in any way that resembles the motion of a whale in the ocean. Relying on conventional physics this only leads rocket propulsion.
The higher the velocity a space whale wants to attain it must exhaust large amounts of reaction mass or its exhaust velocity must be sufficiently high. if a space whale wants to reach a given velocity equivalent to its exhaust velocity then its mass ratio, which the ratio of reaction mass expelled over its final mass, will be approximately a factor of two. Note: this is an approximation value used for illustrative purposes where precision is not a requirement.
Chemical rockets have exhaust velocities of about four (4) km/s; a fusion rocket will be roughly 0.1 c (or 30,000 km/s); photon rockets is 1 c.
For a space whale to move it needs to have a propulsion system incorporated into its body. Chemical rockets are moderately feasible for a living creature (but with lost of caveats). The main drawback is it will take a space whale extremely long time periods for it to travel anywhere, even in a planetary system, let alone interstellar distances where the mass ratio would be massively prohibitive.
Chemically propelled space whale might start off with the mass of a blue whale but it would be reduced to the size of a sardine after boosting to its cruise velocity for modest interstellar trip. Many interplanetary excursions wouldn't be much better.
Fusion propulsion means space whales would need to incorporate fusion reactor technology into their bodies. A space whale now resembles what it will need to be, namely, a cyborg spacecraft. Fusion propulsion will involve low rates of acceleration. Roughly one centimetre per second squared. Interplanetary travel is feasible, while interstellar travel will be at its limits and probably infeasible.
Photonic propulsion requires incorporating serious technology into a cyborg space whale (it is unlikely there will be any other kind) and extremely dangerous too. They effectively need antimatter power systems to make them work well enough to be useful. So unless someone is prepared to feed space whales antimatter this is improbable.
Space whales are part of a highly advanced galactic civilization. Undoubtedly they would to be created from a combination of synthetic biology and cyborgization. This civilization has fast FTL travel technology. Possibly, the creators of the space whales will have equipped their space whales with FTL drive-systems. Once again whatever power systems are required will have to be part of their bodies.
This will enable the space whales to travel rapidly from one location hospitable to their survival to another. Otherwise their travel times will too long for their survival. Although space whales may need to go into a state of cryptobiosis while in transit.
The next level of locomotion for space whales requires consideration of exotic physics. The best example of which is the application of negative mass.
Although no particles are known to have negative mass, physicists (primarily Hermann Bondi in 1957, William B. Bonnor in 1989, then Robert L. Forward) have been able to describe some of the anticipated properties such particles may have. Assuming that all three concepts of mass are equivalent the gravitational interactions between masses of arbitrary sign can be explored, based on the Einstein field equations:
Positive mass attracts both other positive masses and negative masses. Negative mass repels both other negative masses and positive masses.
For two positive masses, nothing changes and there is a gravitational pull on each other causing an attraction. Two negative masses would repel because of their negative inertial masses. For different signs however, there is a push that repels the positive mass from the negative mass, and a pull that attracts the negative mass towards the positive one at the same time.
Hence Bondi pointed out that two objects of equal and opposite mass would produce a constant acceleration of the system towards the positive-mass object, an effect called "runaway motion" by Bonnor who disregarded its physical existence, stating: “ I regard the runaway (or self-accelerating) motion […] so preposterous that I prefer to rule it out by supposing that inertial mass is all positive or all negative. ” — William B. Bonnor, in Negative mass in general relativity.
Such a couple of objects would accelerate without limit (except relativistic one); however, the total mass, momentum and energy of the system would remain 0.
This behavior is completely inconsistent with a common-sense approach and the expected behaviour of 'normal' matter; but is completely mathematically consistent and introduces no violation of conservation of momentum or energy. If the masses are equal in magnitude but opposite in sign, then the momentum of the system remains zero if they both travel together and accelerate together, no matter what their speed:
The main problem with negative mass "runaway motion" drive systems is how to generate the negative mass necessary to propel a space whale. This may be cavalier, but a galactic civilization of the kind postulated by this question should have solved that problem long ago in its history. In fact, they might find it to be quaintly old-fashioned.
In summary, space whale will be cyborg spacecraft. They could be propelled by fusion rocket propulsion systems (a feasible future technology in terms of current science and engineering) or the more exotic negative mass drive system (conceptually plausible, but relies on the existence of the hitherto undiscovered negative mass).