The sol system has entered a region of space where the laws of nature are slightly different. It will experience different physics for 3 years, then things will return to what we know now.

Which of the following decay chains will have the least impact on earth’s biology during those 3 years?

  1. $^{75}\text{As} \rightarrow ^{75}\text{Se} + \text e^- + \overline{v}_e : \lambda = 12d$

  2. $^{74}\text{Ge} \rightarrow ^{74}\text{As} + \text e^- + \overline{v}_e : \lambda = 12d$

Try to include

  • which organisms or ecosystems will be negatively impacted,

  • with references to a clinical information source,

  • and the best possible estimate for when negative effects will become apparent.

(Only one of these changes has occurred alone, all other physics remains unchanged)

  • $\begingroup$ number 2 obviously $\endgroup$ – Kilisi Oct 26 '19 at 22:28
  • $\begingroup$ @Kilisi - oops - fixed. Thanks. $\endgroup$ – Vogon Poet Oct 27 '19 at 1:17
  • $\begingroup$ Why does this matter? $\endgroup$ – Starfish Prime Oct 27 '19 at 8:58
  • $\begingroup$ Because $^74$As decays back to $^74$Ge in 17.74 days, so nothing really happens except electrons flying around. Now at least there is the intended attrition. $\endgroup$ – Vogon Poet Oct 27 '19 at 12:37
  • $\begingroup$ The relevant half-lives also matter a lot. If the half-lives are small, there will be more of an impact. If the half-lives are long, it may not matter much at all. $\endgroup$ – JoshuaZ Oct 27 '19 at 15:24


Ge-74 -> As-74: Germanium was first discovered in 1886, and, as suggested by the late discovery, is a relatively rare metal, as well as not as useful as other metals. It also seems to be biologically inert, and there's no biological process which uses it. It literally has no relevance to organic life. This change will have no effect to organic life. It'll play havoc with camera lenses and optic fibers. But no organic effects.

As-75 -> Se-74: Arsenic is poisonous to organic life, infamously so. To whit, compounds containing it were used as insecticides, until they caused brain damage among the sprayers. That kind of poisonous. And, apparently, it's an essential nutrient in rats. In fact, the linked article even indicated it might be an essential nutrient in humans, though there's no proof. And the vast majority (basically 100%) of Arsenic is in As-75. There are also rare bacteria that use it as a reducing agent. So this three years stint might kill off rats, or at the least cripple them. But then there's also the (very slim) possibility that you've doomed all life on this planet.

  • 1
    $\begingroup$ Selenium is also an essential micro-nutrient which is toxic in large doses. It's neither good or bad for the rats, because the arsenic levels are so low to begin with. $\endgroup$ – Halfthawed Oct 27 '19 at 2:23
  • $\begingroup$ Interesting linked article, or rather its abstract. 45 quid for the whole article is a bit rich. Looks like As is a micro-nutrient useful during certain stressful phases in rodents. Probable outcome: rats under some minor extra stress for 3 years, but certainly not life threatening. $\endgroup$ – a4android Oct 27 '19 at 22:52

Ge --> As will have the most impact. The organisms and their ecosystems most affected will be human beings.

Germanium is an important ingredient in most of our solid state electronic devices. The major part of human electronic technology will fail catastrophically during the three-year period. Phones, computers, fibre optics, solar power technology, and most other electronic gadgetry.

Elemental germanium is used as a semiconductor in transistors and various other electronic devices. Historically, the first decade of semiconductor electronics was based entirely on germanium. Presently, the major end uses are fibre-optic systems, infrared optics, solar cell applications, and light-emitting diodes (LEDs). Germanium compounds are also used for polymerization catalysts and have most recently found use in the production of nanowires. This element forms a large number of organogermanium compounds, such as tetraethylgermanium, useful in organometallic chemistry. Germanium is considered a technology-critical element.

That's the main point. Germanium is a technology-critical element. Germanium decaying into arsenic will impact technology-using organisms. On Earth, that means us.

  • $\begingroup$ The organisms and their ecosystems most affected will be human beings. Germanium is an important ingredient in most of our solid state electronic devices. I hate to be the one to inform you that your smartphone is not part of the "ecosystem". $\endgroup$ – SJuan76 Oct 27 '19 at 9:31
  • $\begingroup$ @SJuan76 and yet, somehow, the use of modern electronics often does have an effect on ecosystems. Must be magic! Surely you don't really believe that the sudden malfunction of a significant percentage of the electronics in the world would have absolutely no effect on any ecosystem at all? $\endgroup$ – Starfish Prime Oct 27 '19 at 10:39
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    $\begingroup$ I would agree that Ge->As will have a greater effect overall, but the effect is more societal and technological. From a solely organic standpoint, which the question posed, I think it's As. $\endgroup$ – Halfthawed Oct 27 '19 at 13:17
  • $\begingroup$ @SJuan76 The human species is a technology-using organism. From a biological point of view if its technology is disrupted, then the human ecosystem is disrupted. PS: It's not just smartphones. I was surprised how much technology would be affected by Ge --> As. $\endgroup$ – a4android Oct 27 '19 at 22:34
  • $\begingroup$ @Halfthawed It's easy for people to think us humans are separate from Earth's biology. Society & technology are part of our human ecosystem. Lose much of our technology & there will be organic impacts. People are likely to die. Perhaps more than rats. $\endgroup$ – a4android Oct 27 '19 at 22:41

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