What is a good theory in science?

How does science work? And what's all this about quantum mechanics?

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uwot
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Re: What is a good theory in science?

Post by uwot » Mon Apr 30, 2018 12:10 am

Philosophy Explorer wrote:
Sun Apr 29, 2018 11:17 pm
What are your thoughts about QM and gravity?
If you really want to know, read my blog: https://willijbouwman.blogspot.co.uk
Philosophy Explorer wrote:
Sun Apr 29, 2018 11:17 pm
They're two theories to explain our universe.
Neither of them are theories. If you drop your pint, it won't fall to the ground in theory; it will actually do so, because something is causing it to fall. Whatever the cause of that falling, it is called gravity. Quite how you managed to miss the list of theories about gravity, is a mystery.
Quantum Mechanics is similarly a whole raft of theories to explain why mass, energy, momentum and whatnot come in discrete packets, and not smoothly, as classical physics assumes.
Philosophy Explorer wrote:
Sun Apr 29, 2018 11:17 pm
Are they really the same theory or distinct? Why can't they be combined as Einstein and many others have tried to do?
It's General Relativity that can't be combined with QM, because as a classical theory, it assumes that spacetime is smooth. According to QM, nothing is smooth. Most of the alternative theories listed above are inspired by this fact, or at least seek to address it.

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Re: What is a good theory in science?

Post by Necromancer » Mon Apr 30, 2018 12:52 am

Philosophy Explorer wrote:
Sat Apr 28, 2018 6:28 am
What characteristics does it have? Should it account for everything? How do we know that it does account for everything? Or is it perpetually fluid and how do we know that?

Which theory is most reliable in science (and how do we know that?)

PhilX 🇺🇸
This is an awfully hard question for philosophy of science that many people have put many hours, weeks and years into. I'll get back to you.

Either way, for a start, you can read about "significance graphs" by Philip Kitcher in his book Science, Truth and Democracy Oxford UP, 2001, pp. 63 to 82, especially graphs on pp. 79 and 80, one dealing with Dolly, the cloned sheep.

:D

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Re: What is a good theory in science?

Post by Philosophy Explorer » Mon Apr 30, 2018 2:43 am

Uwot said:

"Neither of them are theories." Yet gravity (or the general theory of relativity) is a theory which is confusing. Is general relativity a theory (along with QM)?

PhilX 🇺🇸

uwot
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Re: What is a good theory in science?

Post by uwot » Mon Apr 30, 2018 9:09 am

Philosophy Explorer wrote:
Mon Apr 30, 2018 2:43 am
Uwot said:

"Neither of them are theories." Yet gravity (or the general theory of relativity) is a theory which is confusing. Is general relativity a theory (along with QM)?
It's very simple. As I said above, if you drop something do you:
A. Have a theory that it will fall to the ground?
B. Know for a fact that it will fall to the ground?

(Purists and smartypants please note that for the purposes of discussion I will be ignoring Hume and the problem of induction and assume...)
The answer is B.
Things fall to the ground too regularly for it to be a coincidence, so it is reasonable to infer that something is making things fall to the ground.
Whatever that something is, it is called gravity.
Therefore gravity is not a theory; it is a fact.

So what causes gravity? Well, there are a number of different ideas that account for gravity very well. General Relativity is the best known*, but the philosophical model on which it is based i.e. that matter warps 'spacetime', like the dozen or so ideas listed above, is just a theory.**

With QM, it is similarly not a theory that energy comes in packets of a particular size; it is demonstrably the case-a fact, in other words.
There are a number of theories about why this should be so.


*Newton didn't have any idea what causes gravity, he just did the maths, which is why it's a 'law'. The theoretical part of Newton was that the force that makes things fall to the ground, is the same one which keeps planets going round the Sun.
**So is my idea that gravity is basically refraction, but it's easy to understand and there's no maths involved. p32-37 https://willijbouwman.blogspot.co.uk

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Re: What is a good theory in science?

Post by Philosophy Explorer » Mon Apr 30, 2018 9:46 am

uwot wrote:
Mon Apr 30, 2018 9:09 am
Philosophy Explorer wrote:
Mon Apr 30, 2018 2:43 am
Uwot said:

"Neither of them are theories." Yet gravity (or the general theory of relativity) is a theory which is confusing. Is general relativity a theory (along with QM)?
It's very simple. As I said above, if you drop something do you:
A. Have a theory that it will fall to the ground?
B. Know for a fact that it will fall to the ground?

(Purists and smartypants please note that for the purposes of discussion I will be ignoring Hume and the problem of induction and assume...)
The answer is B.
Things fall to the ground too regularly for it to be a coincidence, so it is reasonable to infer that something is making things fall to the ground.
Whatever that something is, it is called gravity.
Therefore gravity is not a theory; it is a fact.

So what causes gravity? Well, there are a number of different ideas that account for gravity very well. General Relativity is the best known*, but the philosophical model on which it is based i.e. that matter warps 'spacetime', like the dozen or so ideas listed above, is just a theory.**

With QM, it is similarly not a theory that energy comes in packets of a particular size; it is demonstrably the case-a fact, in other words.
There are a number of theories about why this should be so.


*Newton didn't have any idea what causes gravity, he just did the maths, which is why it's a 'law'. The theoretical part of Newton was that the force that makes things fall to the ground, is the same one which keeps planets going round the Sun.
**So is my idea that gravity is basically refraction, but it's easy to understand and there's no maths involved. p32-37 https://willijbouwman.blogspot.co.uk
This is what my online encyclopedia has to say:

"Albert Einstein's general theory of relativity is one of the towering achievements of 20th-century physics. Published in 1916, it explains that what we perceive as the force of gravity in fact arises from the curvature of space and time. Einstein proposed that objects such as the sun and the Earth change this geometry."

Have a good day.

PhilX 🇺🇸
Last edited by Philosophy Explorer on Mon Apr 30, 2018 10:18 am, edited 1 time in total.

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Re: What is a good theory in science?

Post by Necromancer » Mon Apr 30, 2018 9:50 am

Philosophy Explorer wrote:
Mon Apr 30, 2018 2:43 am
Uwot said:

"Neither of them are theories." Yet gravity (or the general theory of relativity) is a theory which is confusing. Is general relativity a theory (along with QM)?

PhilX 🇺🇸
I'd say that theory is (merely) the description or law of some relationship that entails a certain data set. This data set is usually considered facts. One should note though that the description by theory is very important for future scientific work, such as astronomy in case of gravity / theory of relativity.

Note also, as a theory becomes well known and (consensus) accepted, popularly speaking, the theory is disregarded and people talk of the phenomenon as a fact, nothing particularly exciting about it.

8)

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Re: What is a good theory in science?

Post by uwot » Mon Apr 30, 2018 11:09 am

Philosophy Explorer wrote:
Mon Apr 30, 2018 9:46 am
This is what my online encyclopedia has to say:

"Albert Einstein's general theory of relativity is one of the towering achievements of 20th-century physics.
Yes it is. What does your online encyclopaedia say about Brans-Dicke, String Theory or Loop Quantum gravity?
Philosophy Explorer wrote:
Mon Apr 30, 2018 9:46 am
Published in 1916, it explains that what we perceive as the force of gravity in fact arises from the curvature of space and time.
This is a bit misleading. It may be a fact that the force of gravity is due to the curvature of spacetime, but if we knew it was a fact, no one would bother with any other theory.
Philosophy Explorer wrote:
Mon Apr 30, 2018 9:46 am
Einstein proposed that objects such as the sun and the Earth change this geometry."
Indeed, but one of the problems with GR is that there is no known mechanism by which matter changes the geometry. As a result, GR depends on an ad hoc hypothesis for which there is no direct empirical evidence; but that has no bearing on the accuracy of the mathematics based on that hypothesis.
Philosophy Explorer wrote:
Mon Apr 30, 2018 9:46 am
Have a good day.
Thanks. You too.

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Re: What is a good theory in science?

Post by Philosophy Explorer » Mon Apr 30, 2018 11:38 am

uwot wrote:
Mon Apr 30, 2018 11:09 am
Philosophy Explorer wrote:
Mon Apr 30, 2018 9:46 am
This is what my online encyclopedia has to say:

"Albert Einstein's general theory of relativity is one of the towering achievements of 20th-century physics.
Yes it is. What does your online encyclopaedia say about Brans-Dicke, String Theory or Loop Quantum gravity?
Philosophy Explorer wrote:
Mon Apr 30, 2018 9:46 am
Published in 1916, it explains that what we perceive as the force of gravity in fact arises from the curvature of space and time.
This is a bit misleading. It may be a fact that the force of gravity is due to the curvature of spacetime, but if we knew it was a fact, no one would bother with any other theory.
Philosophy Explorer wrote:
Mon Apr 30, 2018 9:46 am
Einstein proposed that objects such as the sun and the Earth change this geometry."
Indeed, but one of the problems with GR is that there is no known mechanism by which matter changes the geometry. As a result, GR depends on an ad hoc hypothesis for which there is no direct empirical evidence; but that has no bearing on the accuracy of the mathematics based on that hypothesis.
Philosophy Explorer wrote:
Mon Apr 30, 2018 9:46 am
Have a good day.
Thanks. You too.
I looked up Brans-Dicke. It's a contender to General Relativity, but the theory is held by a minority of physicists.

No online encyclopedia, but we have Wikipedia which is quite technical:

https://en.m.wikipedia.org/wiki/Brans–Dicke_theory

PhilX 🇺🇸

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Re: What is a good theory in science?

Post by Philosophy Explorer » Mon Apr 30, 2018 11:53 am

Do multiple theories have a place in science? Sometimes they can be useful. I've mentioned the case of using company names which a sales tip suggested which is like a theory and seemed to work, except I've proven the theory was no good when I learned about the electronic greeting and did testing, both with and without the company name and found out it made no difference to sales. Then the sales tip influenced me to further check my proven sales technique and had me adjust it for more sales. So I dropped the company name sales tip as it served its purpose and I developed a better sales model.

However I was lucky in this case. Multiple theories might also confuse and slow things down because you don't know what direction to go in. One must be open to different possibilities.

PhilX 🇺🇸

uwot
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Re: What is a good theory in science?

Post by uwot » Mon Apr 30, 2018 10:58 pm

Philosophy Explorer wrote:
Mon Apr 30, 2018 11:38 am
I looked up Brans-Dicke. It's a contender to General Relativity...
It's one of many.
Philosophy Explorer wrote:
Mon Apr 30, 2018 11:38 am
...but the theory is held by a minority of physicists.
That has been true of every theory at some point.

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Re: What is a good theory in science?

Post by Philosophy Explorer » Tue May 01, 2018 1:01 am

Uwot said:

"That has been true of every theory at some point."

Doesn't sound too believable. How many theories are you
acquainted with?

How about the Theory of Evolution? I've never known it to play second fiddle to any other theory.

PhilX 🇺🇸

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Re: What is a good theory in science?

Post by Philosophy Explorer » Tue May 01, 2018 4:26 am

Here's a good question for you, uwot. If a theory is working 100% effectively, then why more theories?

PhilX 🇺🇸

uwot
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Re: What is a good theory in science?

Post by uwot » Tue May 01, 2018 6:07 am

Philosophy Explorer wrote:
Tue May 01, 2018 1:01 am
How about the Theory of Evolution? I've never known it to play second fiddle to any other theory.
I take it you are not from the Bible Belt.

uwot
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Re: What is a good theory in science?

Post by uwot » Tue May 01, 2018 7:02 am

Philosophy Explorer wrote:
Tue May 01, 2018 4:26 am
Here's a good question for you, uwot. If a theory is working 100% effectively, then why more theories?
Different reasons. You could make any theory work 100% by adding ad hoc hypotheses to explain anomalies. You could add more epicycles and equates to Ptolemy's geocentric model and it would work perfectly, but apart from being extremely complicated the idea that we are stationary and that everything else is moving, to most people, is ridiculous.
GR and QM are both working 100%, but they are based on different ideas. GR is based on the idea that the universe is made of smooth stuff, whereas QM shows quite clearly that it is lumpy. So there is a lot of effort put into reconciling these two views.

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Re: What is a good theory in science?

Post by Philosophy Explorer » Tue May 01, 2018 7:56 am

uwot wrote:
Tue May 01, 2018 6:07 am
Philosophy Explorer wrote:
Tue May 01, 2018 1:01 am
How about the Theory of Evolution? I've never known it to play second fiddle to any other theory.
I take it you are not from the Bible Belt.
On average, TOE predominates.

PhilX 🇺🇸

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