Why can't I ask hypothetical questions about situations that can't happen in the first place, if I'm interested in the resulting phenomena and/or said situation will cause?

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    $\begingroup$ You may be interested in Worldbuilding for your hypothetical physics scenarios. $\endgroup$
    – Kyle Kanos
    Mar 21, 2016 at 10:19
  • $\begingroup$ Hi Abdul Moiz Qureshi: I removed your last subquestion about being funny. It is preferred to have only one subquestion per post. $\endgroup$
    – Qmechanic Mod
    Nov 20, 2018 at 14:00
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    $\begingroup$ Bit late, don't you think? But anyway, the first question in the question body is an explanation of what I mean, not a sub question. It would be nice if you can unedit the question. $\endgroup$ Nov 20, 2018 at 18:49
  • $\begingroup$ @AbdulMoizQureshi Perhaps you could make an edit to unambiguously show that the subquestion is related: perhaps something on the lines of "can these hypothetical situations or their implications be humorous?", if I understood your intent correctly. $\endgroup$
    – user191954
    Nov 21, 2018 at 8:49
  • $\begingroup$ That is valid criticism. That sub question is indeed not related to the main question. But then again, perhaps someone will look at these comments, look at the edits, and answer the irrelevant sub question anyway? And no, I do not plan to use this tactic to somehow find loopholes on how many questions you can ask, because that is just asking for trouble. $\endgroup$ Nov 21, 2018 at 9:40
  • $\begingroup$ Can you imagine though? Some one repeatedly editing a single question multiple times into a completely different one, and them adding in the comments section, "do not look through the edit history"? One would give such a trickster points for sheer creativity. $\endgroup$ Nov 21, 2018 at 9:43
  • $\begingroup$ can I ask a hypothetical physics question directly connecting to physics? $\endgroup$ Feb 1, 2019 at 19:23
  • $\begingroup$ I was going to ask one about nuclear fusion $\endgroup$ Feb 1, 2019 at 19:25

1 Answer 1


The simple answer is that science is a description of reality and not a speculative discipline. If you are speculating about a scenario that is not well understood, you can do it as part of hypothesis testing, but if something is well understood, like energy conservation in most regimes, then asking what would happen if it was strongly violated is simply not a scientific question. We can't know what would happen if the laws of nature would not be what they are. Pretty much everything in science is, directly or indirectly, strongly intertwined with everything else. Every one scientific construct is checked and cross-checked for consistency with everything else over and over, again. It's a tightly woven logical fabric. Take one thread out and the entire construction unravels in ways that would require a complete reanalysis that may be just as complex as the process of building what we have now in the first place was... and we would be lacking any guidance from nature, which would turn it, at best, into a field of mathematics.

If you are asking about violations because you are trying to understand the significance of a law or a particular phenomenon, then you can always formulate the question in another way, like

Why is the law of energy conservation so fundamental in physics?


Can we imagine ways in which the law of energy conservation may be broken without unravelling all of physics?

These are actual questions that some physicists are asking for good, both theoretically and experimentally, and they do have important answers.

Sometimes we get questions from science fiction authors (or people who are toying with the idea of becoming one) who want a particular plot device validated by science. My advice for those would be to go one of two ways:

  1. Invent a world with completely different physics. That's safe and it gives you many more means of artistic expression. Some of the best science fiction and fantastic literature is based on that premise.

  2. If you can't do (1), stick slavishly to textbook physics.

Every attempt to walk the fine line between the two that I have seen ended up unmasking the author's inability to stick to his or her own logic. If you need examples for the latter type of literary catastrophe, pretty much every story ever written that has an "ansible" in it belongs into this category and so do almost all stories about time travel. It is extremely difficult to make up scenarios where a plot device lets the author do one particular thing but wouldn't give rise to a much more logical story line that uses the same device in a different way. Unless you are very good at constructing self-consistent story lines (in which case you would likely be making millions in Hollywood, already, and wouldn't have to ask us), don't go there.

  • $\begingroup$ Thanks for the respectful answer. But what I meant was that a law of physics is only temporarily broken, which leads to a physically possible (though improbable) scenario, and then the results of that scenario. This question was written after I asked what would happen if the earth gained a net positive charge of five ( I also implied I was the one who caused it). The message got blocked. What did I do wrong? $\endgroup$ Mar 21, 2016 at 18:14
  • $\begingroup$ I understand, but that's exactly the thing that can't happen. One can, of course, charge the Earth, and it is effectively charged to some potential, but one can't imagine stripping of e.g. half of its electrons and keeping the planet in one piece. That is not how electrodynamics and atomic physics work, so physicists can't help you with that. $\endgroup$
    – CuriousOne
    Mar 21, 2016 at 23:56
  • $\begingroup$ So basically, giving the Earth a positive charge of five will overcome the force of gravity, and lead to the planet's breakup? And if so... what next? $\endgroup$ Mar 22, 2016 at 9:47
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    $\begingroup$ No, "a positive charge of five" is not even a physical sentence. Five what? It wouldn't lead to "breakup". You couldn't add that much charge in an instance. Any attempt to add charge beyond a certain point would lead to loss of charge, first trough the atmosphere and then by ionization of matter on the surface. You would start ionizing stuff on the surface without the interior noticing much. Remember what they told you in school about where charges sit on a sphere. $\endgroup$
    – CuriousOne
    Mar 22, 2016 at 19:00
  • $\begingroup$ Five coulombs.Of course I can't add that much charge, this is a hypothetical situation in which the Earth inexplicably gains a charge.I want to ask a professional what would happen.Would it result to the rapid ionization of everything, until the charge is dissipated?Would it lead to the planet's breakup first? How would a positively charged planet interact with the already slightly positively charged atmosphere? And correct me, but a highly negatively charged earth would lead to huge(It's Earth's SLIGHT negative charge and the atmospheres slight positive charge which leads to lighting, right?) $\endgroup$ Mar 23, 2016 at 4:56
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    $\begingroup$ Five Coulombs? That'a not much charge. You can carry that around in a tiny capacitor in your pocket and the battery in your phone might contain 10000-20000C. The capacitance of Earth is approx. 70uF, if I remember correctly, so 5C will only lead to a potential of approx. 70kV. Nothing bad will happen. I was thinking you meant five times the number of electrons or something ridiculous like that. :-) $\endgroup$
    – CuriousOne
    Mar 23, 2016 at 5:02
  • $\begingroup$ Alright, I meant something ridiculous like twice the electrons. $\endgroup$ Mar 30, 2016 at 17:35
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    $\begingroup$ @AbdulMoizQureshi: Then we are back to square one. :-) That's impossible because the electrons won't stay on the matter distribution. If you want to "squeeze" them in there, you would need enormous gravity, probably enough to cause a highly charged black hole, something which is not known to exist. I don't know if it could exist, I would have to look at the total charge of extremal black holes. That, incidentally, is a great question along the lines "What would be the max. negative charge of an extremal black hole with a given number of positive charges in the progenitor?" $\endgroup$
    – CuriousOne
    Mar 31, 2016 at 1:40
  • $\begingroup$ You forgot getting emotional over someone's comment that doesn't sit well with you. $\endgroup$ May 20, 2016 at 8:25
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    $\begingroup$ @SpicyWeenie: Down votes are just feedback. Learn from it and thrive. $\endgroup$
    – CuriousOne
    May 20, 2016 at 8:29
  • $\begingroup$ @CuriousOne, 'bit' late, but can I ask the hypothetical black hole question you posted in your reply? $\endgroup$ Nov 20, 2018 at 18:51
  • $\begingroup$ So no gedankenexperiments? Wasn't Einstein's wondering what happens if one could approach the speed of light leading to special relativity a speculative discipline? Actually I'm pretty sure you don't mean to disallow all hypothetical scenarios, massless, frictionless things don't exist but we use them all the time to understand the world better. I came by here via this comment which doesn't seem very helpful there (I've also added a bounty). $\endgroup$
    – uhoh
    Feb 23 at 14:40

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