What does nothing look like?

[billhinge]

1 hour ago, iantaylor2uk said:

You can't write it down to the last digit because there isn't one. The fact we can approximate it surely means it exists though.

yes it exists as a concept but 3.14 does not equal 3.1415926535897932384626433 but both are equally valid answers to what is pi, whatever number you pick I can always give you a different value

If you try to measure a circle it then you have to consider if you live in a flat Newtonian universe or a Riemannian universe, if the universe contains matter it can't be perfectly flat although it may be very, very  close in some places. This doesn't take account of your measuring or drawing equipment

How about imaginary numbers, are they real, do tachyons with imaginary mass exist? why not?

By the way when I say somethings exist as concepts it doesn't mean they don't have physical manifestations, some things do and some don't

If you are religious do demons exist, some would say they are real others that they are metaphors

I am being a bit facetious but there is an underlying point, much of the world is based on models, models are definitely useful and work until they fail but all are approximations of reality

 

[ollypenrice]

3 hours ago, andrew s said:

 

Philosophy has dined out for decades on debating what terms like real and nothing mean without any accepted progress. 

 

I like dining out!

More seriously, I'm not sure that Newton regarded space simply as geometry. I may be quite wrong but did he not conceive of it as having a fixed existence, rather as we conceive of grid lines on an OS map? Yes, these are expressions of geometry but they have an absolute relationship with church spires and crossroads, etc. Didn't Euler challenge Newton with a question like, 'What would happen if the Universe moved two feet to the left?' or something like that? It's a very long time since I read Westfall and I'm hardly on home turf with any of this stuff.

Olly

[andrew s]

36 minutes ago, ollypenrice said:

I like dining out!

More seriously, I'm not sure that Newton regarded space simply as geometry. I may be quite wrong but did he not conceive of it as having a fixed existence, rather as we conceive of grid lines on an OS map? Yes, these are expressions of geometry but they have an absolute relationship with church spires and crossroads, etc. Didn't Euler challenge Newton with a question like, 'What would happen if the Universe moved two feet to the left?' or something like that? It's a very long time since I read Westfall and I'm hardly on home turf with any of this stuff.

Olly

I have no idea what Newton actually thought but his theory is one in which space and time can be coordinated with a Euclidean geometry.  In retrospect I was reflecting the  modern view of Newtonian spacetime rather than his.

I am not familiar with Westfall but I know his absolute spacetime was challenged at the time from many angles but its success at predicting the motion of the planets rather confounded them.

Even Einstein's formulation of Special relativity and General Relativity along with Bohr's quantum mechanics are now seen as outdated.

It reminds me that what we think of as fixed changes and morphs with time. The idea of the election of JJ Thompson in 1897 is very different to that of QED.

This thread has weak anti-parallels with Plato and his theory of forms. From Wiki 

"The theory of Forms or theory of Ideas is a philosophical theory attributed to Plato, that the physical world is not as real or true as timeless, absolute, unchangeable ideas."

Regards Andrew 

[billhinge]

Are black holes watching you?

https://www.quantamagazine.org/black-holes-will-destroy-all-quantum-states-researchers-argue-20230307/

In this “participatory universe,” as Wheeler called it, the cosmos expanded and cooled around the U, forming structures and eventually creating observers, like humans and measuring apparatus. By looking back to the early universe, these observers somehow made it real.

“He would say things like ‘No phenomenon is a true phenomenon until it’s an observed phenomenon,’” said Robert M. Wald, a theoretical physicist at the University of Chicago who was Wheeler’s doctoral student at the time.

 

Wheeler is one of the experts who wrote the bible on General Relativity

Edited April 16, 2023 by billhinge

[Moonshed]

It often surprises me the odd things that still remain in my fading memory. I recall reading Michio Kaku’s brilliant book “Hyperspace” printed in 1995. It was Chapter 5 titled “Quantum Heresy” that he was discussing symmetry in physics and he referred to the poet William Blake and his marvellous poem “Tyger! Tyger! Burning bright” and quoted:

Tyger! Tyger! burning bright 

in the forests of the night

What immortal hand or eye

Could frame thy fearful symmetry?

That, to me, sums up Quantum Theory perfectly. 

All theories have their day before some new upstart theory comes along and knocks them off their pedestal. Just think how much Black Hole theory has changed in just a few decades, and is still changing.

Theories are a useful tool to help aid our understanding but to believe they are they are the reality of whatever it is they describe is betting against the odds.

Perhaps one day some clever theoretical physicist will come up with a theory that unites Relativity with Quantum Theory and for a while he or she will bask in the glory until eventually that theory too will be overturned.

Will we ever reach the ultimate theory that cannot be overturned? I doubt it, for then we would know everything there is to know about the universe in which we live, and with that knowledge we would be as gods, and I cannot see the messed up human race ever reaching that pinnacle. Maybe instead it will be reached by AI?

[Albir phil]

Nothing is like infinity by its own definition dose not exist 🤔

[saac]

On 16/04/2023 at 20:30, Moonshed said:

It often surprises me the odd things that still remain in my fading memory. I recall reading Michio Kaku’s brilliant book “Hyperspace” printed in 1995. It was Chapter 5 titled “Quantum Heresy” that he was discussing symmetry in physics and he referred to the poet William Blake and his marvellous poem “Tyger! Tyger! Burning bright” and quoted:

Tyger! Tyger! burning bright 

in the forests of the night

What immortal hand or eye

Could frame thy fearful symmetry?

That, to me, sums up Quantum Theory perfectly. 

All theories have their day before some new upstart theory comes along and knocks them off their pedestal. Just think how much Black Hole theory has changed in just a few decades, and is still changing.

Theories are a useful tool to help aid our understanding but to believe they are they are the reality of whatever it is they describe is betting against the odds.

Perhaps one day some clever theoretical physicist will come up with a theory that unites Relativity with Quantum Theory and for a while he or she will bask in the glory until eventually that theory too will be overturned.

Will we ever reach the ultimate theory that cannot be overturned? I doubt it, for then we would know everything there is to know about the universe in which we live, and with that knowledge we would be as gods, and I cannot see the messed up human race ever reaching that pinnacle. Maybe instead it will be reached by AI?

I think within the scientific community it is pretty well understood that a theory is " a best and incomplete " interpretation  of nature.  If there is any misinterpretation that a theory somehow represents an immutable description of nature then that is surely only held outwith the scientific community and is certainly ill-informed.   Re the theory of everything - I've long held the belief that if the universe is fully "knowable " then the human brain will have the capacity to know it fully. It's the incremental nature of science that allows us to climb what appears as the inaccessible summit.  I guess the trick is, can we survive long enough to complete the assent?

Jim