last day (17 days later) » 

17:42
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A: Is there any known thing or physical object that absolutely cannot be destroyed?

DaleThe fundamental laws of physics are time reversible. So if something cannot be destroyed then it follows that it cannot be created. And if it cannot be created then either it doesn't exist or it has always existed. As far as I know, we don't know of anything that has always existed. So then we do...

So according to science, there is no indestructible thing?
At least according to my knowledge of science. I don't presume to speak authoritatively for all of science.
as dale says from our observations and according to logic en.wikipedia.org/wiki/Logic there is nothing indestructible
@Dale +1 for a nice concise argument.
@annav How does logic fit here? I understand about out observations, but how does logic fit here?
17:42
@Lucas I did give the link in wiki. "Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premises in a topic-neutral way."
@Lucas Time reversibility is irrelevant here. It doesn’t mean that time of a system can be reversed. Time reversibility means that systems can exist, which obey the equations, in which the time coordinate is reversed. For example, a time reversed black hole is a white hole. This means that conceptually white holes may exist. This absolutely does not mean that you can physically reverse the time of a black hole and convert it to a white hole to be destroyed. So a classical (non-evaporating) black hole cannot be destroyed (and no one has ever observed a black hole evaporation).
@annav There is no logic. See my comment above. There are also no observations that black holes can be destroyed.
@Lucas Using a specific example, this answer says, “if black holes cannot be destroyed, then white holes cannot be created”. This is true, but irrelevant. So white holes cannot be created, fine. Who cares? Black holes still cannot be destroyed.
@safesphere the time reverse of a black hole is also a valid solution to GR. So this isn’t really a counter example. However, you do bring up a good point: often the time reverse of something is called by a different name.
JBH
JBH
@safesphere I am by no means an astrophysicist, but isn't the claim that black holes can't be destroyed not quite right?
@safesphere we do not use the same "logic" then. black and white holes in my opinion are like the price of tea in china.
I'm not an astrophysicist either, but why can't black holes be "destroyed"? As far as I've read, black holes can even merge together (which would essentially destroy both and create a new one?). Also, wouldn't "adding mass" also count as destruction, in the sense that the prior state ceases to exist and is altered to something new? I can "destroy" the "smallest black hole in the galaxy" by feeding it - its no longer the "smallest black hole in the galaxy". At the very least, it would warp it, which the question mentions shouldn't be possible. Maybe "information" is a better candidate for this.
17:42
>The fundamental laws of physics are time reversible. So if something cannot be destroyed then it follows that it cannot be created. $$___$$ I very not sure in this logical transition.
With regard to "being destroyed by merging" - I think at this point this becomes a problem of definitions. Say you have two spoons. You use a welder and weld them onto each other. The new construct can be described as one object or two objects welded together depending on your definition of object. Two black holes merging into one black hole can be destruction or cannot be destruction. All it means is that "destruction of something" is not clear enough of a definition to answer the question precisely.
@Katai A black hole can grow and two can merge into one. Whether this counts as “destruction” is up to the OP to decide. It is not clear from his question.
@JBH The Hawking radiation has not been experimentally confirmed. Until then, black holes don’t evaporate.
"So if something cannot be destroyed then it follows that it cannot be created." -- I don't see how one follows the other. Maybe I'm missing some philosophical argument here?
18:00
@safesphere there are also no observations of black holes forming. What's your point?
 
6 hours later…
23:40
What about quantum fields? In QFT to have a particle is a condition in a field. To get rid of the particle, change the form of the field. The particle vanishes, but the field does not. The field itself continues to exist. We have no idea of how to get rid of the field.

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