How to Avoid Breaking Physics With Your “What If” Question

[phinds]

We get a lot of “what if” questions here on Physics Forums. This article will explore three different types and then some suggestions for students who feel their question may fall into one of those types.

“what if” questions that contradict physics as we know it
“what if” questions that are themselves self-contradictory
“what if” questions that can be answered but with some difficulty
suggestions for the student

“What If” Questions That Contradict Physics as We Know It
 
Often here on the Physics Forum, people ask questions that, unrealized by them, amount to being exactly “if the laws of physics don’t apply, what do the laws of physics say about ?”.
Sometimes this is just because of a poorly formulated question. For example, if someone asks “what would happen to the Earth if the sun were to suddenly disappear”, it could well be that what they are really want to know is “does the gravity of the sun affect the Earth instantaneously”. The first question is problematic because it...

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[dedocta]

This is an incredibly useful post as someone new to forums, and rather unsure how and if to post something I've worked on. Thanks phinds!

 

[mattrix]

I know old thread.
@phinds, "What if" questions are par for the course.

Physics principles are taught in isolation, with an unstated "given all other things". The student is left to extrapolate for themselves.
I have a question of my own that violates the laws, and I am not sure how to ask it now.

Isn't
“I know that the atom is not the smallest thing in existence but could physics be made to work if quarks did not exist?”
in the same category as
“What would be the effect if there were no back EMF in a DC motor?”,
I am assuming there is some evidence for the existence of quarks.

There is a need for a place to ask 'stupid' questions and get a quick answer. Stupid questions tend to arise when we are asked to believe a contradiction

 

[russ_watters]

There is a need for a place to ask 'stupid' questions and get a quick answer. Stupid questions tend to arise when we are asked to believe a contradiction

Just make sure you frame it as a question and you should be fine. Framing as a statement/argument like "twins paradox proves special relativity is wrong" is how you get in trouble.