Sub-luminal Space Swimming Safety Science!

An article in the latest (August 2009) edition of Scientific American describes an astronaut floating motionless with respect to his distant spaceship. He is not tethered to the spaceship and has no objects available that can be hurled away or can in some other way create a thrust.

How is he ever going to make it back to his spaceship?

His situation seems hopeless. However, he remembers the lessons he received as rookie astronaut on swimming in empty space. By applying a weird degenerative form of breaststroke the astronaut slowly moves toward the spaceship and makes it safely back before he runs out of oxygen.
Swimming in Space



What to think of this? Repetitive flexing of his muscles causing an astronaut to move through empty space? Swimming without pushing against anything or being pushed by anything? Sounds unbelievable? Literal bootstrapping in a mediocre science fiction scenario? Surely since Newton we know that neither Baron Von Munchausen nor anyone else can pull himself up by his own bootstraps!



Well, think again. MIT professor Jack Wisdom did demonstrate in a paper published in 2003 in Science that it is possible to translate a deformable body solely by applying internal forces.



So you ask: if that is so, why can't we lift ourselves up and breaststroke through the sky? Well, the issue is that professor Wisdom's 'breaststroke' is not particularly effective to overcome earth's gravity, as it relies on the local curvature of spacetime. This curvature is very small, and its effects are hardly noticable in everyday life and over small distances. Yet, since Einstein we know that spacetime is curved due to the presence of mass in the universe.

Distant stars and planets bend spacetime and create a non-Euclidean geometry. Would one measure the sum of the angles of a giant triangle formed in space, these angles would not add up to 180 degress as Euclidean geometry stipulates. It is precisely this deviation from the flat Euclidean geometry that enables swimming through a vacuum.

Any object in motion feels a bit of friction as it moves through the sea of radiation that is constantly emitted by its surroundings.

Glowing cosmos. Any object in motion should feel a tiny slowing force from the sea of light emitted by its surroundings. The glow from the big bang  might have slowed hot debris and affected the early evolution of the Universe.

There’s no escape from friction. Objects moving through a vacuum or even interstellar space feel a universal drag from the photons that are everywhere, according to the 28 November PRL. Although the drag is tiny, the researchers believe it may alter cosmologists’ estimates of the time it took for atoms to coalesce after the big bang. But some cosmologists say the effect, although real, is not relevant to cosmology.

Bring two pieces of metal close enough together, and they will almost always attract or repel one another, even in a vacuum, thanks to the Casimir effect. This minute force comes from virtual photons–particles of light–that continually flit in and out of existence. The effect leads to friction as one chunk of metal moves past another. Rudi Podgornik, of the University of Ljubljana, Slovenia, and his colleagues imagined taking away the second chunk, and wondered what the remaining piece of metal would experience simply moving through space.

Their calculations show that a lone object in motion experiences friction. It comes from the sea of real photons emitted by everything around it. Night vision goggles prove that any warm body emits infrared light, but even frigid intergalactic space is awash in microwave photons that would gradually slow a drifting space traveler. The friction occurs because the moving object absorbs more photons at its front surface than at its rear. The object slows from the flow of photons, just as a cyclist is slowed by the wind she feels in her face.

After establishing the mechanism, the team worked out exactly how long it would take various materials to slow down in different situations. A metal would feel a stronger drag than a nonmetal, Podgornik and his colleagues found, because metals can absorb light at all frequencies, unlike nonmetals. In intergalactic space, the slowing of a macroscopic object would only be noticeable over billions of years. In a 1000-degree-Kelvin oven, on the other hand, a water molecule would need less than five months to slow to a standstill, assuming it started out at the oven’s temperature

Vantablack is a substance made of carbon nanotubes and is the blackest substance known, absorbing a maximum of 99.965% of radiation in the visible spectrum. It is composed of a forest of vertical tubes which are "grown". When light strikes vantablack, instead of bouncing off, it becomes trapped and is continually deflected between the tubes before eventually becoming heat.