Science ebook recommendations

[WT Sharpe]

I'm certainly no expert on quantum mechanics, but I know enough to know that there are even interpretations in which the wave function never collapses; such as the many worlds hypothesis, in which all possible outcomes are actually experienced.

[HarryT]

Originally Posted by Rizla

Lanza dedicates a chapter to the experiment and addresses your point and gives a physical example that rebuts your statement. I read this part several times because I needed to be sure. If I get a chance later, I will give you details of his example, but maybe you should just read the book yourself. He spends a chapter referencing the double-split experiment and it's very early in the book.

Rizla, as a (former) professional physicist myself, I have to say that this guy sounds like a kook. Quantum mechanics works according to the laws of probability; consciousness ain't a part of "the rules". I really have no wish to read crackpot books about things that I already understand.

[HarryT]

Originally Posted by WT Sharpe

I'm certainly no expert on quantum mechanics, but I know enough to know that there are even interpretations in which the wave function never collapses; such as the many worlds hypothesis, in which all possible outcomes are actually experienced.

There are indeed, but given that the observable results of the Copenhagen interpretation and the "many worlds" hypothesis are identical, it's rather like arguing about how many angels can dance on the head of a pin. It simply doesn't matter.

[jbjb]

Originally Posted by WT Sharpe

I'm certainly no expert on quantum mechanics, but I know enough to know that there are even interpretations in which the wave function never collapses; such as the many worlds hypothesis, in which all possible outcomes are actually experienced.

But from within one of the worlds there's no way of telling whether the other worlds exist - i.e. whether the wave function collapsed or reality forked in such a way as to provide a separate universe for each possible outcome. From our point of view within our reality, the observable effect in either case is that the wave function collapsed.

In terms of making useful, measurable predictions about reality, the many worlds hypothesis adds nothing to the Copenhagen interpretation.

/JB

[HarryT]

Originally Posted by jbjb

But from within one of the worlds there's no way of telling whether the other worlds exist - i.e. whether the wave function collapsed or reality forked in such a way as to provide a separate universe for each possible outcome. From our point of view within our reality, the observable effect in either case is that the wave function collapsed.

In terms of making useful, measurable predictions about reality, the many worlds hypothesis adds nothing to the Copenhagen interpretation.

/JB

Which is what I've just said in the post immediately above yours .

[jbjb]

Originally Posted by HarryT

Which is what I've just said in the post immediately above yours .

Indeed - I didn't see your response until after posting mine! :-)

In any case - it appears we agree.

/JB

[HarryT]

We certainly do!

[WT Sharpe]

As a layperson, my understanding of the Copenhagen interpretation is that it's not there to help people understand QM, it's there to provide a way for people to do QM, to run the numbers and get repeatable, usable results; a "shut up and run the numbers" kind of deal. As far as understanding QM, I'm reminded of what Richard Feynman said in his book, The Character of Physical Law: "I think I can safely say that nobody understands quantum mechanics."

[HarryT]

Originally Posted by WT Sharpe

As a layperson, my understanding of the Copenhagen interpretation is that it's not there to help people understand QM, it's there to provide a way for people to do QM, to run the numbers and get repeatable, usable results; a "shut up and run the numbers" kind of deal.

Yes, exactly. You can assign a probability to each outcome.

As far as understanding QM, I'm reminded of what Richard Feynman said in his book, The Character of Physical Law: "I think I can safely say that nobody understands quantum mechanics."

I always knew that I was smarter than Mr Feynman .

[WT Sharpe]

Originally Posted by HarryT

...I always knew that I was smarter than Mr Feynman .

What did he know? He even scribbled on a perfectly good van!

[HarryT]

It's actually an interesting point: that there's a whole lot of physics that we know isn't "correct", but it produces good enough results to get the job done. Newton's law of gravity, for example, assuredly isn't "correct", but you can use it perfectly satisfactorily to get a spacecraft safely from Earth to Mars. It's only in extreme conditions that you need to switch to General Relativity (and even General Relativity we know is not "right").

[WT Sharpe]

Originally Posted by HarryT

It's actually an interesting point: that there's a whole lot of physics that we know isn't "correct", but it produces good enough results to get the job done. Newton's law of gravity, for example, assuredly isn't "correct", but you can use it perfectly satisfactorily to get a spacecraft safely from Earth to Mars. It's only in extreme conditions that you need to switch to General Relativity (and even General Relativity we know is not "right").

And sometimes the conditions under which General Relativity comes into play aren't even so extreme as to be outside of things that impact our lives, such as adjusting the clocks on GPS satellites.

[HarryT]

Originally Posted by WT Sharpe

And sometimes the conditions under which General Relativity comes into play aren't even so extreme as to be outside of things that impact our lives, such as adjusting the clocks on GPS satellites.

True.

[jbjb]

Originally Posted by HarryT

It's actually an interesting point: that there's a whole lot of physics that we know isn't "correct", but it produces good enough results to get the job done. Newton's law of gravity, for example, assuredly isn't "correct", but you can use it perfectly satisfactorily to get a spacecraft safely from Earth to Mars. It's only in extreme conditions that you need to switch to General Relativity (and even General Relativity we know is not "right").

Absolutely, and that's in many ways a good indication about what science is all about. It's about building useful models which can make good predictions in certain circumstances, and knowing what the boundaries of those circumstances are. It's about improving the models, pushing back the boundaries within which they are accurate, or finding other models whose boundaries cover other areas.

What it's not about is some sort of metaphysical "truth". There are constant efforts to unify our theories as much as possible, with the eventual goal of having one which covers everything, but it's still "just" a model.

Going back to the point about understanding QM - it's not really clear to me what "understanding" means in this case. Does it mean "knows the equations and can do the maths"; does it mean "has a feel for the *consequences* of QM"; does it mean "has an intuitive understanding about how a QM system will behave"?

/JB

[HarryT]

Originally Posted by jbjb

Going back to the point about understanding QM - it's not really clear to me what "understanding" means in this case. Does it mean "knows the equations and can do the maths"; does it mean "has a feel for the *consequences* of QM"; does it mean "has an intuitive understanding about how a QM system will behave"?

Perhaps even "understanding what a wave function really is"? At a level "beyond" simply a mathematical construct? I'm not sure that I do, but equally, I'm not sure that it's necessary to do so.