View source for Known to be astronomically unlikely

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= Quantifyavble "impossibility" =

== The "airslap" ==

The molecules of the air can by pure chance "decide" to line up in their thermal motion in such a way that they give you a hefty slap in the face. <br>
No joke. That indeed is possible at any moment in time. It is just ridiculously unlikely. <br>
In fact one can precisely calculate the probability of that happening.

Well, given small enough objects that actually happens observably and all the time. <br>
It's juts especially large jostles in the course of [[brownian motion]]. <br>
These are essentially just that. Microscopic "airslaps".

== Related ==

Surface diffusion rates for [[crystolecule]]s (even with a surprisingly small surface contact area for a [[Van der Waals force]] bond) are astronomically low.

Atom placement error rates in [[piezochemical mechanosynthesis]] can be digital data processing bit error level low. <br> 
That is not quite astronomically low though. By no means [[FAPP]] irrelevant. <br>
The presence of placemen errors still has consequences for design choices.

= Unquantifyable "impossibility" =

Finding ways to go beyond what we think is some [[ultimate limit]] of technology may seems "astronomically unlikely" to happen. <br>
Of course no one is and no one will ever be able to tell for certain that no surprising new physics will crop up that would allow us to eventually exceed one or more of these fundamental limits. <br>
'''But:''' <br>
Given that despite long and intense scientific search nothing has been popping up <br>
there is very good reason to assume (to "first approximation") that no such limit breaking surprises will pop up anytime soon.

Nanoscale [[PPV]] chambers that only perform vacuum clock out (no lock in) will have with [[FAPP]] certainty not a single gas atom inside of them.

== Fantasy SciFi ==

One of course one can assume any kind of desired fantasy physics and build fantasy technology on top of that. <br>
That sort of activity could be called [[wishful thinking]] or [[fantasy engineering]]. <br>
It is mostly useful for soft SciFi entertainment but nothing much more. <br>
That kond of activity is all ok and well (we don't want any ban against artistic thinking) <br>
as long as the SciFi fantasy author is in full knowledge of the currently totally non-existent (and quite likely remaining so) foundation.

Usually it works the other way around though. <br> 
First the SciFi fantasy author comes up with a desired fantasy technology <br>
then the fantasy physics is matched to fit the needs of this fantasy technology. <br>
That is if the author even goes to the commendable trouble of coming up with some halfway plausible fantasy physics <br>
in an attempt to explain the technology.

== Serious exploration (quantifyable) ==

The above must not be confused with [[exploratory engineering]]. Which is pretty much the polar opposite of [[fantasy engineering]]. <br>
An exploratory engineer: 
* gets rid of all physics that is not well established (fantasy physics if absolutely off limits) and then 
* extrapolates solely based upon the remaining most well established physics. And finally 
* adds large safety margins. Assuming much less performance than more realistic math would predict.

Note that (once some new knowledge has been established) in [[exploratory engineering]] it is very much allowed and not forbidden to go the other way: <br>
* (1) Pick (via educated guess of what could be possible) a some technology that would be nice to have and then 
* (2) check if it lies withing the limits that where formerly confirmed to be spanned by some precedingly done [[exploratory engineering]].

Predictions about complex technologies with many specialized sub-technologies are quite a bit more risky than <br>
predictions about base performance parameters though. <br>

= Related =

* '''[[Impossible]]'''
* [[Ultimate limits]]
* [[For all practical purposes]]
'''Philosophical nonsense:'''
* [[Big bang as spontaneous demixing event]] <br><small>When there cannot be observers no matter the how ludacrisly large the physical "time" the experienced time shrinks down to zero.</small>

= External links =

* [https://en.wikipedia.org/wiki/Poincar%C3%A9_recurrence_theorem Poincaré recurrence theorem]
* Recurrence violates the [https://en.wikipedia.org/wiki/Second_law_of_thermodynamics second law of thermodynamics] – no, you still can't extract useful energy from a system in thermodynamic equilibrium – in case you wondered
* See: "[https://en.wikipedia.org/wiki/Brownian_ratchet Feynman ratchet]" for why that is.