Is there any positive N on which it's agreed among astronomers that 10^-N is accepted as, or treated as 0 (zero)?

I think one of the sciences that most precision is required is astrophysics.

I'm aware of my hardware capacity to lowest floating number, but that's not what I'm asking about.

  • $\begingroup$ I'm voting to close this question as off-topic because It's entirely situation-dependent. $\endgroup$ – Carl Witthoft Mar 6 '19 at 19:55
  • $\begingroup$ Hardware computing capacity has nothing to do with it. Google "extended precision library" for example. Are you asking about uncertainty limits? $\endgroup$ – Carl Witthoft Mar 6 '19 at 19:56
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    $\begingroup$ I don't understand what this is asking. Of course in some models, certain aspects are considered negligible but that will vary from model to model. Of course nobody actually thinks that a non-zero value is equal to zero. So "Of course not" seems to be the answer, but I think that is not what the OP is actually asking about. However I don't know what the OP is actually asking. $\endgroup$ – James K Mar 6 '19 at 21:48
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    $\begingroup$ @uhoh your voting strategy doesn't seem to make sense: you close so you can reopen? I agree the question is on-topic, but no parameters were given so it's unclear, which is why it was closed. The "On Hold" message invites the OP to edit it into a useful question; the links are worth reading, especially Good Subjective, Bad Subjective. If you think the question has intrinsic value, you could always have put the effort into editing it instead of answering it... $\endgroup$ – Chappo Hasn't Forgotten Monica Mar 7 '19 at 3:50
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    $\begingroup$ Hi everyone. I am actually an old SO user & know the rules. With all my respect, I think this is a simple question with a clear statement. (I questioned the possible existence of parameter N and got a nice answer.) I tried however really could not understand the point of view of 'this is not a proper question' supporters. Lastly, many thanks to @uhoh for editing the q. best regards. $\endgroup$ – Andre Chenier Mar 7 '19 at 5:44

Is there any positive N on which it's agreed among astronomers that 10^-N is accepted as 0 (zero)?

No, there isn't.

Astronomy overlaps with cosmology and there can be some pretty big and small numbers.

However most physical parameters also have units and the units chosen affect the numerical values.

A great example is the Jansky:

The jansky (symbol Jy, plural janskys) is a non-SI unit of spectral flux density, or spectral irradiance, used especially in radio astronomy. It is equivalent to 10^−26 watts per square metre per hertz.

In some cases one might even imagine going the other way and using L☉/ℓP² myr (solar luminosities per square planck-length per million years) which would require numerical values about 1x10^-110 times smaller.

Instead, astronomers and other scientists usually decide is something is small enough that it doesn't matter within the context of the current discussion. THey use words like negligible and small to indicate they're going to ignore it.

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    $\begingroup$ thanks for the detailed answer and your correction to my question. I am not a native English speaker. My q is more clear now and tells exactly what I meant. Best regards. $\endgroup$ – Andre Chenier Mar 7 '19 at 5:35
  • $\begingroup$ @AndreChenier thank you for accepting the answer, it's possible there may be more answers as soon as your question is reopened, so keep an eye on the question for changes. Welcome to Stack Exchange! $\endgroup$ – uhoh Mar 7 '19 at 5:36

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