geordief

So we can talk about curved 3d space or curved 4d spacetime? They are different models..... I was only familiar with the concept of curved 4d spacetime. Could you perhaps explain(or give me a pointer) how one would measure a curvature in 3d space .** I think I understand the principle of curvature in 4d spacetime. **I suppose it must refer to the surface of a sphere?

You can have gravity in flat space?(apologies for naivety or misunderstanding)

A comment in the ongoing "Nature of Time" thread made me wonder what gravity would look like if the Galilean version of Relativity was correct I have seen the animations depicting Galilean spacetime diagrams and wonder whether or not they can be extrapolated to a model of gravity in a similar way to how AE moved on to GR from Special Relativity. Just to say,I am not attempting to attach any credence to Galilean Relativity. I just wonder if that model might be stretched to incorporate a kind of Galilean General Relativity and what "Galiliean Gravity" might look like.

A friend used to carry a pet mouse in his pocket.. When I once worked in a fish factory we used to fill the freezer storage room at the end of the day and my fellow workers included me in their ongoing game of locking each other in. I didn't take the joke one bit well and I don't remember it happening again.

If a muon is modeled** as a perturbation in its field,does this perturbation have a frequency? Could that (if it exists and is as I dimly imagine it) be considered as a kind of internal mechanism even it is unchanging ? (A bit like the standing waves or seiches presently being discussed over the Great Lakes in Canada) ** in QFT

Ah,now I think I understand Markus' point From the muon's perspective no time passes ? The decay is spontaneous and randomly timed from an observer's frame?

They don't lose a small amount of mass every time they decay? Does the mass of the muon somehow remain the same even though it is continuously losing mass to the environment? (if indeed it is) Is it because the mass is relativistic?

What happens when muons decay?Do they not lose mass with each particle they emit? If so ,is that not change?

But it is only noticeable/quantifiable under those circumstances** isn't it?(even though it does occur at any relative speed or in the slightest gravitational field) **ie at relative speeds and in very strong gravitational fields,

Do you have radioactive decay in mind? Any other examples? Would it be useful to define "change" and how it is quantified? Is it another way of saying "entropy"? Unless they were snowed under? Does that just happen when frames move at relativistic speeds wrt each other or in intense gravitational fields?

@DrmDoc sorry and disregard my last post.I see my question was answered from the outset of the thread. It is a pretty dense (and oldish) thread and so I may not plough through it just yet. Maybe you are finished with it anyway? Very good 😀

You think dreams are more a response to stimuli that actually occur during the time we are asleep than a response to stimuli that have occured during the waking hours? What kind of stimuli occur when we are asleep?(I have not gone back through the thread;perhaps you have already explained this there?)

I hope I didn't overdo it.(it is a very ,very famous quote though) Might be more startling if an AI machine decided that it didn't exist(could happen too)

Well baby steps are always best ,especially in the icy conditions we have had the past week.

Don't we already know that?Who doubts the existence of an objective reality**? Isn't it the subjective reality that is or is not in question? Or did you mean" there is thinking, therefore something exists...in our subjective consciousness?" **that our senses approximate to and can mislead about.

Definitions are always important.As per the title of the OP this is hardly a purely scientific discussion. I can see why religious or Marxist-leninist discussions would leave a sour taste but I wouldn't include the question of "what is reality?" to be in the gutter with them,even if it has no obvious usefulness and may have been done to death over the years.

That is what I always thought too**Maybe we need a non layman philosopher to sort the wheat from the chaff **although,as I said I was aware for some time that some were saying that this was not the "true" meaning....

That is not very reassuring or pleasant if the pinacle of our intellectual understanding is "there are thoughts" I just had a quick look at the subject where the meaning of "cogito ergo sum" was discussed(did Descartes write in Latin,I wonder ?) and the gist was that he may have been giving a riposte to the seemingly then prevalent idea that ,because we can know nothing for sure then it follows that we can not even say that we even exist . Apparently according to what I just read ,he was really saying "I doubt and therefore I exist" The suspension of credulity saves the individual from being washed away by delusion (A bit like my first known philosopher ,Socrates said (of other puffed up "philosophers " of his day) "I know nothing, but I know that I know nothing" The latter is a creation of the former? As a painter can create a landscape ,so can he or she create a self portrait. AI is a creature of its creator .It can turn against its creator in the same way the son may kill the father .

"Should"as in that is what Descartes was actually saying ,or "should" as in that he misspoke and said the wrong thing? I have heard it said quite often that the saying has been misinterpreted but am not clear on what this means. Did he say/write this the one time only ?Was it "Je pense donc je suis" or was it some variant of that?

What, no candy wrapper patrols on the Big Rock Candy Mountain?

Or going through the rubbish looking for evidence pointing to the identity of the culprit.That can be satisfying. This happened to a close friend who was very annoyed and wrote them a letter to put her case but she ended up paying the fine (over a hundred euros) It wasn't fly tipping or casual littering but putting the wrong kind of rubbish in the wrong place.

Is that a software/hardware distinction or do those definitions bleed into each other?

You mean Russia has enough of these drones to overwhelm Ukraine's defenses and prolong the blackouts through the whole winter? Do you think the Patriots would have a role in combating the drones that are causing the damage at the moment?

I not sure how effective the Patriot anti-missile system would be against Russia's current campaign against the civilian infrastructure. I get the feeling it may be more intended to counter what may be in the pipeline regarding larger more accurate missiles that Iran may provide in the near future. I think the cost of the Patriots against the current drones may be extremely lopsided and I hope that Ukraine may weather the present storm without needing to use Patriot systems.

Imagine (not to hard I know) that in the near medium or farther out future that our civilisation managed to bring itself to the point where further "civilized" life was no longer possible on this planet Also the option of continuing on planets in tha Solar system was judged unrealistic. Under those circumstances might our descendants who could themselves at this existential dead end find a way to broadcast their dna across the galaxy with the aim of colonizing another planetary system even if all the members of their current civilisation were doomed to perish? What methods might be employed to "seed" another planetary system? Might a virus or viruses be modified that could carry the dna of the expiring civilisation? Could some record of that civilisation also be embodied into the code? I understand that a lot of the human (and other?)dna is surplus to requirements.Could that be used as "storage space"?