You all know me.

What new course should I choose to teach at U3A?

What new course would you choose to teach at U3A?

mollwollfumble said:

You all know me.

What new course should I choose to teach at U3A?

What new course would you choose to teach at U3A?

You:
Lateral thinking

Me:
Using Excel with numbers that don’t start with $

What is U3A?

sibeen said:

What is U3A?

University for old codgers.

sibeen said:

What is U3A?

University of the Third Age I’d reckon.

Peak Warming Man said:

sibeen said:

What is U3A?

University of the Third Age I’d reckon.

At my age it’d have to be U4A.

sibeen said:

What is U3A?

https://en.wikipedia.org/wiki/University_of_the_Third_Age

The Rev Dodgson said:

mollwollfumble said:

You all know me.

What new course should I choose to teach at U3A?

What new course would you choose to teach at U3A?

You:
Lateral thinking

Me:
Using Excel with numbers that don’t start with $

I like that. I’m not really that good at lateral; thinking, though. I can do it, but I’ll never be a de Bono. For instance, De Bono uses the example “what do you make a white road from” and comes up with the answer “glass”. I never would have thought of that, I’m too edjukated.

Michael V said:

sibeen said:

What is U3A?

https://en.wikipedia.org/wiki/University_of_the_Third_Age

Calling it “university” though is something of a euphemism. A lot of the subjects are more like kindergarten level (eg. slow walking, art for fun, how to take a photograph).

For me, I was thinking possibly two new subjects I’d like to teach. Trying to get zero overlap.

1) Science: Life and the universe.
The cell, life as we know it, timeline of evolution, alternative origins of life, life as we don’t know it, the universe as we know it, the universe timeline, which multiverse?

2) Science: Basics and highlights.
Observation, citizen science, hypothesis, analysis, holistic, first principles, literature search, traps to avoid, big science, news in science.

I’d like to teach a course on “applied mathematics”, but I don’t think I could manage it, I could teach it but nobody in the class would understand it. Ditto a course on “mathematics for fun”.

mollwollfumble said:

I’d like to teach a course on “applied mathematics”, but I don’t think I could manage it, I could teach it but nobody in the class would understand it. Ditto a course on “mathematics for fun”.

I suspect the students might have a different concept of “fun” :)

One of my patients lectures in physics at the local U3A. Or did. He kept trying to get me to join.

The Rev Dodgson said:

mollwollfumble said:

I’d like to teach a course on “applied mathematics”, but I don’t think I could manage it, I could teach it but nobody in the class would understand it. Ditto a course on “mathematics for fun”.

I suspect the students might have a different concept of “fun” :)

The fun maths I learnt the other day.

If you tie a rope around the Earth and then want to have the rope raised 1 metre off the ground the increase in length required is just over six metres. The fun bit is that it is exactly the same for Jupiter or the Sun.

sibeen said:

The Rev Dodgson said:

mollwollfumble said:

I’d like to teach a course on “applied mathematics”, but I don’t think I could manage it, I could teach it but nobody in the class would understand it. Ditto a course on “mathematics for fun”.

I suspect the students might have a different concept of “fun” :)

The fun maths I learnt the other day.

If you tie a rope around the Earth and then want to have the rope raised 1 metre off the ground the increase in length required is just over six metres. The fun bit is that it is exactly the same for Jupiter or the Sun.

Or a cricket ball.

sibeen said:

sibeen said:

The Rev Dodgson said:

I suspect the students might have a different concept of “fun” :)

The fun maths I learnt the other day.

If you tie a rope around the Earth and then want to have the rope raised 1 metre off the ground the increase in length required is just over six metres. The fun bit is that it is exactly the same for Jupiter or the Sun.

Or a cricket ball.

It’s a trap.

sibeen said:

The Rev Dodgson said:

mollwollfumble said:

I’d like to teach a course on “applied mathematics”, but I don’t think I could manage it, I could teach it but nobody in the class would understand it. Ditto a course on “mathematics for fun”.

I suspect the students might have a different concept of “fun” :)

The fun maths I learnt the other day.

If you tie a rope around the Earth and then want to have the rope raised 1 metre off the ground the increase in length required is just over six metres. The fun bit is that it is exactly the same for Jupiter or the Sun.

why is it so?

ChrispenEvan said:

sibeen said:

The Rev Dodgson said:

I suspect the students might have a different concept of “fun” :)

The fun maths I learnt the other day.

If you tie a rope around the Earth and then want to have the rope raised 1 metre off the ground the increase in length required is just over six metres. The fun bit is that it is exactly the same for Jupiter or the Sun.

why is it so?

It just is :)

sibeen said:

ChrispenEvan said:

sibeen said:

The fun maths I learnt the other day.

If you tie a rope around the Earth and then want to have the rope raised 1 metre off the ground the increase in length required is just over six metres. The fun bit is that it is exactly the same for Jupiter or the Sun.

why is it so?

It just is :)

I hope we find the answer one day.

sibeen said:

sibeen said:

The Rev Dodgson said:

I suspect the students might have a different concept of “fun” :)

The fun maths I learnt the other day.

If you tie a rope around the Earth and then want to have the rope raised 1 metre off the ground the increase in length required is just over six metres. The fun bit is that it is exactly the same for Jupiter or the Sun.

Or a cricket ball.

You’re just increasing the diameter of a circle by 2 metres – so it’s pi*2.

sibeen said:

ChrispenEvan said:

sibeen said:

The fun maths I learnt the other day.

If you tie a rope around the Earth and then want to have the rope raised 1 metre off the ground the increase in length required is just over six metres. The fun bit is that it is exactly the same for Jupiter or the Sun.

why is it so?

It just is :)

The radius of the globe doesn’t matter. If you want to raise the rope 1 metre off the surface then the rope length needs to increase by 2π.

Michael V said:

sibeen said:

sibeen said:

The fun maths I learnt the other day.

If you tie a rope around the Earth and then want to have the rope raised 1 metre off the ground the increase in length required is just over six metres. The fun bit is that it is exactly the same for Jupiter or the Sun.

Or a cricket ball.

You’re just increasing the diameter of a circle by 2 metres – so it’s pi*2.

WOW, so you’ve found the answer MV. Bloody brill.

sibeen said:

sibeen said:

ChrispenEvan said:

why is it so?

It just is :)

The radius of the globe doesn’t matter. If you want to raise the rope 1 metre off the surface then the rope length needs to increase by 2π.

That’s right elbow in on MVs discovery.

ChrispenEvan said:

Michael V said:

sibeen said:

Or a cricket ball.

You’re just increasing the diameter of a circle by 2 metres – so it’s pi*2.

WOW, so you’ve found the answer MV. Bloody brill.

Well, no, I worked it out. In my head.

ChrispenEvan said:

sibeen said:

sibeen said:

It just is :)

The radius of the globe doesn’t matter. If you want to raise the rope 1 metre off the surface then the rope length needs to increase by 2π.

That’s right elbow in on MVs discovery.

Sigh. Back to my garden.

Length of rope = 2πr

Raise rope off globe by 1 metre then the length of rope = 2π(r+1)

Difference = 2π(r+1) – 2πr

=2πr + 2π -2πr

=2π

sibeen said:

Length of rope = 2πr

Raise rope off globe by 1 metre then the length of rope = 2π(r+1)

Difference = 2π(r+1) – 2πr

=2πr + 2π -2πr

=2π

LOL, I know. It’s an old one. Even The Ancients weren’t bedazzled.

ChrispenEvan said:

sibeen said:

Length of rope = 2πr

Raise rope off globe by 1 metre then the length of rope = 2π(r+1)

Difference = 2π(r+1) – 2πr

=2πr + 2π -2πr

=2π

LOL, I know. It’s an old one. Even The Ancients weren’t bedazzled.

I’d heard it before but was reading something the other day that mentioned it. It really does seem counter intuitive.

sibeen said:

ChrispenEvan said:

sibeen said:

Length of rope = 2πr

Raise rope off globe by 1 metre then the length of rope = 2π(r+1)

Difference = 2π(r+1) – 2πr

=2πr + 2π -2πr

=2π

LOL, I know. It’s an old one. Even The Ancients weren’t bedazzled.

I’d heard it before but was reading something the other day that mentioned it. It really does seem counter intuitive.

it does, cos you think the earth so big the length has to change a lot.

sibeen said:

ChrispenEvan said:

sibeen said:

Length of rope = 2πr

Raise rope off globe by 1 metre then the length of rope = 2π(r+1)

Difference = 2π(r+1) – 2πr

=2πr + 2π -2πr

=2π

LOL, I know. It’s an old one. Even The Ancients weren’t bedazzled.

I’d heard it before but was reading something the other day that mentioned it. It really does seem counter intuitive.

Very.

That’s hard to get your head around, so it’s the earth, the sun, Jupiter and a cricket ball.
Now you tell Barnaby Joyce that and he wont believe you.

Maybe moll can teach A History of Aboriginals, or Non-Aerodynamic Rocket Design, or Great Sewerage Plants of Melbourne.

Divine Angel said:

…or Great Sewerage Plants of Melbourne.

need a botanist for that.

sibeen said:

ChrispenEvan said:

sibeen said:

Length of rope = 2πr

Raise rope off globe by 1 metre then the length of rope = 2π(r+1)

Difference = 2π(r+1) – 2πr

=2πr + 2π -2πr

=2π

LOL, I know. It’s an old one. Even The Ancients weren’t bedazzled.

I’d heard it before but was reading something the other day that mentioned it. It really does seem counter intuitive.

I’d never heard it before.

sibeen said:

ChrispenEvan said:

sibeen said:

The fun maths I learnt the other day.

If you tie a rope around the Earth and then want to have the rope raised 1 metre off the ground the increase in length required is just over six metres. The fun bit is that it is exactly the same for Jupiter or the Sun.

why is it so?

It just is :)

Pie.

Michael V said:

sibeen said:

ChrispenEvan said:

LOL, I know. It’s an old one. Even The Ancients weren’t bedazzled.

I’d heard it before but was reading something the other day that mentioned it. It really does seem counter intuitive.

I’d never heard it before.

Neither have I and to be brutally Frank I don’t believe it.

sibeen said:

The Rev Dodgson said:

mollwollfumble said:

I’d like to teach a course on “applied mathematics”, but I don’t think I could manage it, I could teach it but nobody in the class would understand it. Ditto a course on “mathematics for fun”.

I suspect the students might have a different concept of “fun” :)

The fun maths I learnt the other day.

If you tie a rope around the Earth and then want to have the rope raised 1 metre off the ground the increase in length required is just over six metres. The fun bit is that it is exactly the same for Jupiter or the Sun.

> I suspect the students might have a different concept of “fun” :)

Yeah, that was the problem I had last time. Difficult to teach “mathematics is fun” to someone who can’t understand algebra.

mollwollfumble said:

For me, I was thinking possibly two new subjects I’d like to teach. Trying to get zero overlap.

1) Science: Life and the universe.
The cell, life as we know it, timeline of evolution, alternative origins of life, life as we don’t know it, the universe as we know it, the universe timeline, which multiverse?

2) Science: Basics and highlights.
Observation, citizen science, hypothesis, analysis, holistic, first principles, literature search, traps to avoid, big science, news in science.

I’d like to teach a course on “applied mathematics”, but I don’t think I could manage it, I could teach it but nobody in the class would understand it. Ditto a course on “mathematics for fun”.

Trying to elucidate “first principles”, I found that there were rather a large number of them that I use.

1. Cause comes before effect.
This is obvious but occasionally it gets ignored. a). With Milankovic variations as an explanation of ice ages, there is a strong correlation but occasionally effect comes before cause. b). With El Nino as an explanation of Australia’s rainfall, again there is a strong correlation but there isn’t a time lag.

2. Newton’s laws. Conservation of space, conservation of mass, conservation of momentum, statics, elasticity, gravity causes things to fall down unless in orbit, coriolis, centrifugal force, angular momentum.

3. Laws of thermodynamics. Compressing gas makes it hot, work generates heat, conservation of energy but also loss of energy, heat causes expansion, heat passes by conduction, convection and radiation.

4. Chemical laws. Water is H₂O, periodic table, pH, the speed of a chemical reaction is proportional to the surface area. Spectral lines identify atoms and chemicals.

5. Animal action requires a motive.

6. The Earth’s surface can be divided into the atmosphere, biosphere, hydrosphere, lithosphere, and anthroposphere.

6. The four main states of matter.

7. The five main senses.

8. The laws of optics. Light travels in straight lines except when it doesn’t. Inverse square law. X-ray diffraction.

9. The laws of acoustics. Putting an obstacle between source and receiver makes sound quieter. Resonance. All work generates sound. Speed of sound.

10. Laws of radioactivity. Radioactivity has a half life. The shorter the half life the higher the energy. Alpha radiation is blocked by a piece of tissue paper. E=mc²

11. Laws of electricity and magnetism.

12. Murphy’s law and the law of conservation of belief.

13. Laws of statistics. Everything is risky.

14. Deeper rocks are older. Deeper rocks are hotter. Pressure increases with depth.

15. Evolution is a balance between DNA mutation and natural selection. The greater the difference between species, the further back they diverged.

That just about covers it. Unless you can think of something else that could be classed as “bleedin’ obvious”?

mollwollfumble said:

mollwollfumble said:

For me, I was thinking possibly two new subjects I’d like to teach. Trying to get zero overlap.

1) Science: Life and the universe.
The cell, life as we know it, timeline of evolution, alternative origins of life, life as we don’t know it, the universe as we know it, the universe timeline, which multiverse?

2) Science: Basics and highlights.
Observation, citizen science, hypothesis, analysis, holistic, first principles, literature search, traps to avoid, big science, news in science.

I’d like to teach a course on “applied mathematics”, but I don’t think I could manage it, I could teach it but nobody in the class would understand it. Ditto a course on “mathematics for fun”.

Trying to elucidate “first principles”, I found that there were rather a large number of them that I use.

1. Cause comes before effect.
This is obvious but occasionally it gets ignored. a). With Milankovic variations as an explanation of ice ages, there is a strong correlation but occasionally effect comes before cause. b). With El Nino as an explanation of Australia’s rainfall, again there is a strong correlation but there isn’t a time lag.

2. Newton’s laws. Conservation of space, conservation of mass, conservation of momentum, statics, elasticity, gravity causes things to fall down unless in orbit, coriolis, centrifugal force, angular momentum.

3. Laws of thermodynamics. Compressing gas makes it hot, work generates heat, conservation of energy but also loss of energy, heat causes expansion, heat passes by conduction, convection and radiation.

4. Chemical laws. Water is H₂O, periodic table, pH, the speed of a chemical reaction is proportional to the surface area. Spectral lines identify atoms and chemicals.

5. Animal action requires a motive.

6. The Earth’s surface can be divided into the atmosphere, biosphere, hydrosphere, lithosphere, and anthroposphere.

6. The four main states of matter.

7. The five main senses.

8. The laws of optics. Light travels in straight lines except when it doesn’t. Inverse square law. X-ray diffraction.

9. The laws of acoustics. Putting an obstacle between source and receiver makes sound quieter. Resonance. All work generates sound. Speed of sound.

10. Laws of radioactivity. Radioactivity has a half life. The shorter the half life the higher the energy. Alpha radiation is blocked by a piece of tissue paper. E=mc²

11. Laws of electricity and magnetism.

12. Murphy’s law and the law of conservation of belief.

13. Laws of statistics. Everything is risky.

14. Deeper rocks are older. Deeper rocks are hotter. Pressure increases with depth.

15. Evolution is a balance between DNA mutation and natural selection. The greater the difference between species, the further back they diverged.

That just about covers it. Unless you can think of something else that could be classed as “bleedin’ obvious”?

I was going to post this in its own thread, or maybe a blog post, but I’ll start of here.

16. Actually the basic laws of physics do have a time direction, even excluding entropy. This week’s New Scientist states that “the basic laws of classical and quantum physics run just as well backwards as forwards”, implying that they act the same regardless of time direction; but that’s just wrong.

mollwollfumble said:

mollwollfumble said:

For me, I was thinking possibly two new subjects I’d like to teach. Trying to get zero overlap.

1) Science: Life and the universe.
The cell, life as we know it, timeline of evolution, alternative origins of life, life as we don’t know it, the universe as we know it, the universe timeline, which multiverse?

2) Science: Basics and highlights.
Observation, citizen science, hypothesis, analysis, holistic, first principles, literature search, traps to avoid, big science, news in science.

I’d like to teach a course on “applied mathematics”, but I don’t think I could manage it, I could teach it but nobody in the class would understand it. Ditto a course on “mathematics for fun”.

Trying to elucidate “first principles”, I found that there were rather a large number of them that I use.

1. Cause comes before effect.
This is obvious but occasionally it gets ignored. a). With Milankovic variations as an explanation of ice ages, there is a strong correlation but occasionally effect comes before cause. b). With El Nino as an explanation of Australia’s rainfall, again there is a strong correlation but there isn’t a time lag.

2. Newton’s laws. Conservation of space, conservation of mass, conservation of momentum, statics, elasticity, gravity causes things to fall down unless in orbit, coriolis, centrifugal force, angular momentum.

3. Laws of thermodynamics. Compressing gas makes it hot, work generates heat, conservation of energy but also loss of energy, heat causes expansion, heat passes by conduction, convection and radiation.

4. Chemical laws. Water is H₂O, periodic table, pH, the speed of a chemical reaction is proportional to the surface area. Spectral lines identify atoms and chemicals.

5. Animal action requires a motive.

6. The Earth’s surface can be divided into the atmosphere, biosphere, hydrosphere, lithosphere, and anthroposphere.

6. The four main states of matter.

7. The five main senses.

8. The laws of optics. Light travels in straight lines except when it doesn’t. Inverse square law. X-ray diffraction.

9. The laws of acoustics. Putting an obstacle between source and receiver makes sound quieter. Resonance. All work generates sound. Speed of sound.

10. Laws of radioactivity. Radioactivity has a half life. The shorter the half life the higher the energy. Alpha radiation is blocked by a piece of tissue paper. E=mc²

11. Laws of electricity and magnetism.

12. Murphy’s law and the law of conservation of belief.

13. Laws of statistics. Everything is risky.

14. Deeper rocks are older. Deeper rocks are hotter. Pressure increases with depth.

15. Evolution is a balance between DNA mutation and natural selection. The greater the difference between species, the further back they diverged.

That just about covers it. Unless you can think of something else that could be classed as “bleedin’ obvious”?

> 5. Animal action requires a motive.

5. Animal action requires a motive. Maslow’s hierarchy of needs. Johari window. Cognitive dissonance theory.

The Rev Dodgson said:

I was going to post this in its own thread, or maybe a blog post, but I’ll start of here.

16. Actually the basic laws of physics do have a time direction, even excluding entropy. This week’s New Scientist states that “the basic laws of classical and quantum physics run just as well backwards as forwards”, implying that they act the same regardless of time direction; but that’s just wrong.

That’s a good number 16.

The laws of Newtonian physics, Relativity and Quantum mechanics all work the same regardless of time direction. Ditto the first law of thermodynamics.

It’s only the second law of thermodynamics that doesn’t.

I, personally, think the definition of “basic” needs to be taken back to front in this case. ie. I think the really basic fundamental law is that “closed time loops don’t exist”. And that the second law of thermodynamics is a consequence of that. Rather than the other way around. Because the one-direction definition of time existed at the point of origin of the universe before any particles were created, but the second law of thermodynamics had to wait until there were sufficient particles in the universe for statistical mechanics to work.

So, my version of 16 is:
16. We can only travel forwards in time. We can only see backwards in time.

mollwollfumble said:

That’s a good number 16.

The laws of Newtonian physics, Relativity and Quantum mechanics all work the same regardless of time direction. Ditto the first law of thermodynamics.

It’s only the second law of thermodynamics that doesn’t.

But that isn’t true.

For instance, If I analyse the response of a structure to varying time loads, and if I include even a rudimentary model of non-linear behaviour; the response will be totally different if I run the analysis in reverse.

The Rev Dodgson said:

mollwollfumble said:

That’s a good number 16.

The laws of Newtonian physics, Relativity and Quantum mechanics all work the same regardless of time direction. Ditto the first law of thermodynamics.

It’s only the second law of thermodynamics that doesn’t.

But that isn’t true.

For instance, If I analyse the response of a structure to varying time loads, and if I include even a rudimentary model of non-linear behaviour; the response will be totally different if I run the analysis in reverse.

they don’t follow the laws of physics ¿

SCIENCE said:

The Rev Dodgson said:

mollwollfumble said:

That’s a good number 16.

The laws of Newtonian physics, Relativity and Quantum mechanics all work the same regardless of time direction. Ditto the first law of thermodynamics.

It’s only the second law of thermodynamics that doesn’t.

But that isn’t true.

For instance, If I analyse the response of a structure to varying time loads, and if I include even a rudimentary model of non-linear behaviour; the response will be totally different if I run the analysis in reverse.

they don’t follow the laws of physics ¿

Well they follow simplifications of the laws of physics to be sure, but even if they modelled every quark with laws as precise as quantum mechanics allows, the behaviour in reverse would be nothing like a rewind of the behaviour forwards.

The Rev Dodgson said:

SCIENCE said:

The Rev Dodgson said:

But that isn’t true.

For instance, If I analyse the response of a structure to varying time loads, and if I include even a rudimentary model of non-linear behaviour; the response will be totally different if I run the analysis in reverse.

they don’t follow the laws of physics ¿

Well they follow simplifications of the laws of physics to be sure, but even if they modelled every quark with laws as precise as quantum mechanics allows, the behaviour in reverse would be nothing like a rewind of the behaviour forwards.

Which nonlinear behaviour? Euler buckling is nonlinear but reversible. Ditto nonlinear elasticity. Ditto geometric nonlinearity. So the response would be the same if you run the analysis in reverse (unless you exceed critical load in buckling)

Creep, on the other hand is not, nor work hardening. These are just an examples of the second law of thermodynamics.

> even if they modelled every quark with laws as precise as quantum mechanics allows, the behaviour in reverse would be nothing like a rewind of the behaviour forwards

With properly set boundary conditions, it’s exactly the same forwards as backwards. But setting those boundary conditions correctly – not so easy.

eg. beta decay. You can reverse beta decay by arranging for a neutrino to come in on exactly the right vector and energy, but getting a neutrino to do exactly that would be very difficult.

mollwollfumble said:

The Rev Dodgson said:

SCIENCE said:

they don’t follow the laws of physics ¿

Well they follow simplifications of the laws of physics to be sure, but even if they modelled every quark with laws as precise as quantum mechanics allows, the behaviour in reverse would be nothing like a rewind of the behaviour forwards.

Which nonlinear behaviour? Euler buckling is nonlinear but reversible. Ditto nonlinear elasticity. Ditto geometric nonlinearity. So the response would be the same if you run the analysis in reverse (unless you exceed critical load in buckling)

Creep, on the other hand is not, nor work hardening. These are just an examples of the second law of thermodynamics.

> even if they modelled every quark with laws as precise as quantum mechanics allows, the behaviour in reverse would be nothing like a rewind of the behaviour forwards

With properly set boundary conditions, it’s exactly the same forwards as backwards. But setting those boundary conditions correctly – not so easy.

eg. beta decay. You can reverse beta decay by arranging for a neutrino to come in on exactly the right vector and energy, but getting a neutrino to do exactly that would be very difficult.

It seems that the myth of physics having no direction of time is so ingrained that it is accepted without question, even when it is obviously wrong.

Creep is not “just an example of the second law of thermodynamics”, neither is work hardening.

Reinforced concrete does not have elastic behaviour under working loads.
Neither does soil.
The cause of the non-elastic behaviour is not the 2nd law of thermodynamics. It is because once bonds break, or particles slip, that action cannot be undone by applying the same actions in reverse.

The Rev Dodgson said:

mollwollfumble said:

The Rev Dodgson said:

Well they follow simplifications of the laws of physics to be sure, but even if they modelled every quark with laws as precise as quantum mechanics allows, the behaviour in reverse would be nothing like a rewind of the behaviour forwards.

Which nonlinear behaviour? Euler buckling is nonlinear but reversible. Ditto nonlinear elasticity. Ditto geometric nonlinearity. So the response would be the same if you run the analysis in reverse (unless you exceed critical load in buckling)

Creep, on the other hand is not, nor work hardening. These are just an examples of the second law of thermodynamics.

> even if they modelled every quark with laws as precise as quantum mechanics allows, the behaviour in reverse would be nothing like a rewind of the behaviour forwards

With properly set boundary conditions, it’s exactly the same forwards as backwards. But setting those boundary conditions correctly – not so easy.

eg. beta decay. You can reverse beta decay by arranging for a neutrino to come in on exactly the right vector and energy, but getting a neutrino to do exactly that would be very difficult.

It seems that the myth of physics having no direction of time is so ingrained that it is accepted without question, even when it is obviously wrong.

Creep is not “just an example of the second law of thermodynamics”, neither is work hardening.

Reinforced concrete does not have elastic behaviour under working loads.
Neither does soil.
The cause of the non-elastic behaviour is not the 2nd law of thermodynamics. It is because once bonds break, or particles slip, that action cannot be undone by applying the same actions in reverse.

Are we claiming that the preimages of physical states under forward time transforms, are indeterminate ¿

SCIENCE said:

The Rev Dodgson said:

mollwollfumble said:

Which nonlinear behaviour? Euler buckling is nonlinear but reversible. Ditto nonlinear elasticity. Ditto geometric nonlinearity. So the response would be the same if you run the analysis in reverse (unless you exceed critical load in buckling)

Creep, on the other hand is not, nor work hardening. These are just an examples of the second law of thermodynamics.

> even if they modelled every quark with laws as precise as quantum mechanics allows, the behaviour in reverse would be nothing like a rewind of the behaviour forwards

With properly set boundary conditions, it’s exactly the same forwards as backwards. But setting those boundary conditions correctly – not so easy.

eg. beta decay. You can reverse beta decay by arranging for a neutrino to come in on exactly the right vector and energy, but getting a neutrino to do exactly that would be very difficult.

It seems that the myth of physics having no direction of time is so ingrained that it is accepted without question, even when it is obviously wrong.

Creep is not “just an example of the second law of thermodynamics”, neither is work hardening.

Reinforced concrete does not have elastic behaviour under working loads.
Neither does soil.
The cause of the non-elastic behaviour is not the 2nd law of thermodynamics. It is because once bonds break, or particles slip, that action cannot be undone by applying the same actions in reverse.

Are we claiming that the preimages of physical states under forward time transforms, are indeterminate ¿

If you mean that the future outcomes of current conditions are not predictable, even in principle, then yes, I do claim that, although what I actually wrote made a different point.

The Rev Dodgson said:

SCIENCE said:

The Rev Dodgson said:

It seems that the myth of physics having no direction of time is so ingrained that it is accepted without question, even when it is obviously wrong.

Creep is not “just an example of the second law of thermodynamics”, neither is work hardening.

Reinforced concrete does not have elastic behaviour under working loads.
Neither does soil.
The cause of the non-elastic behaviour is not the 2nd law of thermodynamics. It is because once bonds break, or particles slip, that action cannot be undone by applying the same actions in reverse.

Are we claiming that the preimages of physical states under forward time transforms, are indeterminate ¿

If you mean that the future outcomes of current conditions are not predictable, even in principle, then yes, I do claim that, although what I actually wrote made a different point.

(A) Is that claimed to be due to QM derivatives, or is there another physical principle at play ¿

(B) What other point, we thought reversing physics would involve inversing functions.

SCIENCE said:

The Rev Dodgson said:

SCIENCE said:

Are we claiming that the preimages of physical states under forward time transforms, are indeterminate ¿

If you mean that the future outcomes of current conditions are not predictable, even in principle, then yes, I do claim that, although what I actually wrote made a different point.

(A) Is that claimed to be due to QM derivatives, or is there another physical principle at play ¿

(B) What other point, we thought reversing physics would involve inversing functions.

(A) I think that QM makes the conclusion near certain, but I suspect that even without QM chaotic interactions that cannot be defined to infinite precision would have the same effect.

(B) Although you can’t predict how real things will behave exactly, or in the long term even approximately, you can derive a reasonable approximation of how simple systems will behave in the short term. If you do such a simplified analysis it will always work the same going forwards in time, and it will always work the same with time reversed, but my point is these two analyses will not be mirror images of each other. If you start with conditions at the end of the forward analysis, and apply external actions exactly in reverse, you will not end up with the starting conditions.

The Rev Dodgson said:

SCIENCE said:

The Rev Dodgson said:

If you mean that the future outcomes of current conditions are not predictable, even in principle, then yes, I do claim that, although what I actually wrote made a different point.

(A) Is that claimed to be due to QM derivatives, or is there another physical principle at play ¿

(B) What other point, we thought reversing physics would involve inversing functions.

(A) I think that QM makes the conclusion near certain, but I suspect that even without QM chaotic interactions that cannot be defined to infinite precision would have the same effect.

(B) Although you can’t predict how real things will behave exactly, or in the long term even approximately, you can derive a reasonable approximation of how simple systems will behave in the short term. If you do such a simplified analysis it will always work the same going forwards in time, and it will always work the same with time reversed, but my point is these two analyses will not be mirror images of each other. If you start with conditions at the end of the forward analysis, and apply external actions exactly in reverse, you will not end up with the starting conditions.

(A) Fair shot, we accept practical limitation to physical extrapolation.

(B) We agree that a naïve formulation of “reverse” as “reflect” is… naïve.

SCIENCE said:

The Rev Dodgson said:

SCIENCE said:

(A) Is that claimed to be due to QM derivatives, or is there another physical principle at play ¿

(B) What other point, we thought reversing physics would involve inversing functions.

(A) I think that QM makes the conclusion near certain, but I suspect that even without QM chaotic interactions that cannot be defined to infinite precision would have the same effect.

(B) Although you can’t predict how real things will behave exactly, or in the long term even approximately, you can derive a reasonable approximation of how simple systems will behave in the short term. If you do such a simplified analysis it will always work the same going forwards in time, and it will always work the same with time reversed, but my point is these two analyses will not be mirror images of each other. If you start with conditions at the end of the forward analysis, and apply external actions exactly in reverse, you will not end up with the starting conditions.

(A) Fair shot, we accept practical limitation to physical extrapolation.

(B) We agree that a naïve formulation of “reverse” as “reflect” is… naïve.

So do we agree that there is a direction of time implicit in both Newtonian mechanics and QM?

The Rev Dodgson said:

SCIENCE said:

The Rev Dodgson said:

(A) I think that QM makes the conclusion near certain, but I suspect that even without QM chaotic interactions that cannot be defined to infinite precision would have the same effect.

(B) Although you can’t predict how real things will behave exactly, or in the long term even approximately, you can derive a reasonable approximation of how simple systems will behave in the short term. If you do such a simplified analysis it will always work the same going forwards in time, and it will always work the same with time reversed, but my point is these two analyses will not be mirror images of each other. If you start with conditions at the end of the forward analysis, and apply external actions exactly in reverse, you will not end up with the starting conditions.

(A) Fair shot, we accept practical limitation to physical extrapolation.

(B) We agree that a naïve formulation of “reverse” as “reflect” is… naïve.

So do we agree that there is a direction of time implicit in both Newtonian mechanics and QM?

Not quite, we probably agree that

(A) dynamical systems are chaotic, and

(B) there is a “standard” or “conventional” direction of time implicit in our usual formulations of physics.

SCIENCE said:

The Rev Dodgson said:

SCIENCE said:

(A) Fair shot, we accept practical limitation to physical extrapolation.

(B) We agree that a naïve formulation of “reverse” as “reflect” is… naïve.

So do we agree that there is a direction of time implicit in both Newtonian mechanics and QM?

Not quite, we probably agree that

(A) dynamical systems are chaotic, and

(B) there is a “standard” or “conventional” direction of time implicit in our usual formulations of physics.

I’m not sure of the significance of adding ““standard” or “conventional”“

The Rev Dodgson said:

SCIENCE said:

The Rev Dodgson said:

So do we agree that there is a direction of time implicit in both Newtonian mechanics and QM?

Not quite, we probably agree that

(A) dynamical systems are chaotic, and

(B) there is a “standard” or “conventional” direction of time implicit in our usual formulations of physics.

I’m not sure of the significance of adding ““standard” or “conventional”“

It’s a sign.

+t

SCIENCE said:

The Rev Dodgson said:

SCIENCE said:

Not quite, we probably agree that

(A) dynamical systems are chaotic, and

(B) there is a “standard” or “conventional” direction of time implicit in our usual formulations of physics.

I’m not sure of the significance of adding ““standard” or “conventional”“

It’s a sign.

+t

If it helps, within the above we are specially also suggesting something like: Conway life B3/S23 generates a particular pattern of evolution over time; reversal may or may not be deterministic (it isn’t, but that isn’t our point); as far as we are aware reversal is not Conway life B-3/S-2-3*.

*: even if we choose mod 8 if we like, that is, B5/S56