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Set in the not so distant future nearly all commercial, private and military spaceships capable of fractional speed of light travel would always have a time keeping device powered by radioactive isotope. This is contradicting a doctrine which would have eliminated every traces of nuclear materials on the surface of Earth, actually most of it were buried deep beneath the dirt and sea floor. What is the reason for it not being banned and replaced by advanced technology with unparalleled accuracy and precision?

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    $\begingroup$ "Eliminated every traces of nuclear materials": good luck with that... For example, radioactive carbon-14 is constantly produced in the upper layers of the atmosphere by natural processes; it mixes with the rest of the air, and is absorbed by plants. Plants are radioactive. The plants are then eaten by animals, including humans. People are radioactive. $\endgroup$ – AlexP Jan 30 at 6:48
  • $\begingroup$ @AlexP: there is already an existing list of radioactive materials and in the future there will be some changes to it. $\endgroup$ – user6760 Jan 30 at 6:54
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    $\begingroup$ "There is already a list": radioactive is radioactive, list or no list. And anyway, atomic clocks do not use the kind of material used in nuclear bombs or nuclear power plants. In fact, atomic clocks are pretty ordinary items; most designs do not use radioactive materials at all. $\endgroup$ – AlexP Jan 30 at 8:11
  • $\begingroup$ Postulating that there will be advance technology to replace what you banned is silly. There currently is no alternative to atomic clocks in sight for precision timekeeping. $\endgroup$ – Whitecold Jan 30 at 8:33
  • $\begingroup$ I have rolled back your edit. Edits cannot invalidate existing answers $\endgroup$ – L.Dutch - Reinstate Monica Jan 30 at 9:44
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Atomic clocks do not use radioactive isotopes

Atomic clocks are not radioactive. They do not rely on atomic decay. Rather, they have an oscillating mass and a spring, just like ordinary clocks.

The big difference between a standard clock in your home and an atomic clock is that the oscillation in an atomic clock is between the nucleus of an atom and the surrounding electrons. This oscillation is not exactly a parallel to the balance wheel and hairspring of a clockwork watch, but the fact is that both use oscillations to keep track of passing time. The oscillation frequencies within the atom are determined by the mass of the nucleus and the gravity and electrostatic "spring" between the positive charge on the nucleus and the electron cloud surrounding it.

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  • $\begingroup$ More precise and accurate atomic clock uses thorium isotope. $\endgroup$ – user6760 Jan 30 at 7:37
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    $\begingroup$ Th-229m is the only known isotope so far that could be optically accessed, it is a very special case. The proposed thorium clock can possibly be more precise than other atomic clocks, but that is yet to be proven, but the performance of the laser may well be the limiting factor in the end. In any case, the amounts of Thorium required are minuscule, and of no concern unless you swallow the source. $\endgroup$ – Whitecold Jan 30 at 8:43
  • $\begingroup$ I made an edit just now. $\endgroup$ – user6760 Jan 30 at 9:14
  • $\begingroup$ If they use gravity, won't they be useless in a space ship? $\endgroup$ – Sulthan Jan 30 at 19:04
  • $\begingroup$ @Sulthan I'm pretty sure the wording of the quoted text is imprecise. It's not the gravity of the Earth, etc. It's the attraction between the nucleus and the electron in the subject atom. Probably "gravity" is negligible in this case, being many factors of 10 (if I recall, 10^40) smaller than the electromagnetic forces. Even in an atomic clock the difference will be too small to detect. $\endgroup$ – puppetsock Jan 30 at 20:01
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a doctrine which would have eliminated every traces of nuclear materials on the surface of Earth

The doctrine is plainly dumb and ill conceived.

There are no materials which are radiation free, and we live in a radioactive background. Just to give you a few examples:

  • ever heard of C14 dating? we are all radioactive, since we have unstable carbon-14 nuclei in our bodies. Same does our food, wooden furniture, anything organic. And that C14 is constantly produced in our atmosphere.
  • water has traces of tritium in it, making it radioactive, again.
  • bananas are notoriously radioactive, due to having potassium isotopes

Following that doctrine to the letter would mean burying everything under a layer of still radioactive material.

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  • $\begingroup$ Unfortunately bananas and a glass of water are not in the radioactive material list, maybe I will call the authority to update the list asap ;P $\endgroup$ – user6760 Jan 30 at 6:42
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    $\begingroup$ @user6760 , there is a semi-official radiation dose unit - Banana equivalent dose. Lethal dose is 50-100 bananas at once. Be carefull! Be safe! $\endgroup$ – ksbes Jan 30 at 6:54
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    $\begingroup$ @ksbes, you're out by several orders of magnitude. Average daily exposure is 100BED, lethal is 35,000,000 BED. $\endgroup$ – Separatrix Jan 30 at 9:16
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    $\begingroup$ One more example to demonstrate how poorly conceived this idea is: it would require them to sequester all granite beneath the sea floor, granite containing significant quantities of potassium-40, uranium, thorium, and the decay chains of these, including radon which escapes as a gas. There's several major mountain ranges they'd have to bury. $\endgroup$ – Christopher James Huff Jan 31 at 1:01
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    $\begingroup$ No smoke detectors either! Or X-ray machines. Indeed a very silly doctrine. $\endgroup$ – GrandmasterB Jan 31 at 4:19
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The most obvious solution seems to be that the phrase, "the law applies to the surface of the Earth" is too limited to prevent nuclear technology use among spacecraft. First, the law doesn't specify that nuclear materials are illegal in space. Second, even if it did, Earth governments have no jurisdiction off the surface of the Earth, or at least no real way to enforce their laws. Third, even if they could enforce them, how would they practically find every single atomic clock?

We can take this in several different directions. Perhaps radioactive isotopes are mined in the asteroid belt, on the moon, or in Martian colonies; that way, no part of production ever violates the law on Earth.

Importantly, space colonization as we know it can't exist without nuclear power. Today, many probes are powered by onboard reactors, which is one of the most efficient, dependable ways to keep them running. In the future, the advent of relativistic spacecraft implies interstellar travel - resulting in distances at which solar panels are effectively useless. Nuclear power may be the only option for spaceships, so why would something as trivial as an atomic clock matter next to a reactor - unless the law changes?

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    $\begingroup$ Make sense the long arm of the law stretches only so far. $\endgroup$ – user6760 Jan 30 at 7:09
  • $\begingroup$ I made an edit just now. $\endgroup$ – user6760 Jan 30 at 9:14

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