Physics is inaccurate!

ISAW · 20-06-2005 11:26pm

planck2 wrote:

To everyone on this thread bar Son Goku. Physics is about explaining the universe with mathemathical models which are elegant but computationally useful. Sometimes we get the models correct experiments back us up and some times we get it wrong that's why experiments are there to put us on the right track. If physics was wrong,you wouldn't have for example: a mobile phone, a fridge, a car radio, aeroplanes. The list is endless.

But one could claim it is more than that. Natural Philosophy (physics) is a way of explaining the world and producing useful models of it but "blue skies" research is not about application at all! Scientists do not have to produce products for the market or "solutions" to problems. Sometimes scientists can find new knowledge and not know what "usefull" new product this knowledge might be used to produce. To suggest that science is about producing goods is bad enough but to suggest that the justification for how "right" it is as a model, based on the fact that without it being right one would not have new products, is, I would suggest, ludicrous!

Sapien · 21-06-2005 1:02am

nesf wrote:

Well, what would it appear to be?

...

nesf wrote:

What I'm arguing is the percieved notion of physical fact in the public mind.

I recognise, of course, that you may be affecting this voice for the purposes of illustration. If so - bravo, you are entirely believable as one with no scientific training.

But you go on to say:

nesf wrote:

My point was that physicists talk about the "correctness" of their theories...

To clarify - is the above observation still in the voice of the "public mind", is it an actual contention of yours, or is it both?

Son Goku · 21-06-2005 1:51pm

When you say inaccurate are you leaning more towards the numerically inaccurate side or the descriptively inaccurate side.

nesf · 21-06-2005 3:24pm

Son Goku wrote:

When you say inaccurate are you leaning more towards the numerically inaccurate side or the descriptively inaccurate side.

Descriptively.

The numerical side is self contained and seperate from reality if you want to look at it that way.

The point is, are you describing reality, or are you describing a description of reality?

Son Goku · 21-06-2005 4:37pm

Well I think you are describing reality as most of the models do allow exact solutions.

For instance, in General Relativity, the Field Equation does allow exact solutions for arbitrary mass configurations. One can thereby use the metric to calculate geodesics which are the trajectories of free falling particles.
These correspond exactly with experiment, which would lead me to believe that you are modelling reality.
(Although this usually the domain of Numerical Relativity.)

Even if the validity of the Field Equation becomes questionable in the quantum realm, I don't think that affects it as a descriptive model.

nesf · 21-06-2005 4:51pm

Son Goku wrote:

Well I think you are describing reality as most of the models do allow exact solutions.

For instance, in General Relativity, the Field Equation does allow exact solutions for arbitrary mass configurations. One can thereby use the metric to calculate geodesics which are the trajectories of free falling particles.
These correspond exactly with experiment, which would lead me to believe that you are modelling reality.
(Although this usually the domain of Numerical Relativity.)

Even if the validity of the Field Equation becomes questionable in the quantum realm, I don't think that affects it as a descriptive model.

Agreed. But the point is that you need to grasp what said models actually represent.

Arguing that quantum and GR are reconciliable because the universe is reconcileable misses the point. People confuse models and reality. Physics isn't so much a description of reality but a seperate logical construction that we can use to predict it. But it doesn't ever claim to be or shouldn't ever be considered as anything but a logical construct. Science is the study of reality. But it isn't reality.

The whole purpose of this thread was to get people to see this. I've dropped the argument at this point because, well, i'm bored

I should probably add that this is a philosophy of science topic rather than a purely scienitific one. But I personally feel that anyone who studies science and skips the philosphy is ignoring the most important part.

That's just my opinion though.

Son Goku · 21-06-2005 5:10pm

Well I'll end my arguement with this post.

I would say that even though it is a model of reality, physics does tell you about reality.

An electron does exist, there are electrons. Even though they are fundamental items in our mathematical descriptions, I would say they still exist. Simply as the large scale flow of more fundamental constructions.
There is a physical entity that is the "electron" from our theories.

An example would be velocity. Even though velocity is, in special relativity, the unitless Mikowskian angle between two coordinate systems, it can still be thought of as displacement with respect to time.

Of course "dx/dt" is only a model of what is occuring it is essentially true. Your position is changing over time. In that sense the model does describe reality, it tells you about reality.

Similarly when two cars collide their collision depends on momentum. The cars do posses a momentum. "mv" would be the mathematical representation of this concept, it does describe a property of the cars resultant from two other properties.
Even though this changes in the Special Relativistic and Quantum Mechanical range, I don't think it changes the fact that within the Newtonian range collisions mainly depend on the rest mass and change in Euclidean position over time.

MrAbc · 21-06-2005 9:11pm

Perhaps it would have been more conventional to debate the thread in terms of, "the general public has been misled into believing current physics as absolute truth"... is that what you were getting at, nesf? Whether or not you would eventally fully agree with such a proposition is entirely a different matter.

The general topic seemed to get confused between things asserted in a devil's advocate manner being intermingled with your own thoughts, if I understand the situation correctly

On a final note: you've mentioned "reality" and "describing a description" etc... well [apart from whether one thinks that using a model or description as a fair way of ever considering your reality], you'd have to point out that a particular conflict, in physics, between descriptive beauty versus numerical power is a significant factor in muddying people's understanding of what's more real... the problem may be that for many, outside of everyone learning enough physics, it's difficult to see what the conflict entails or that it ever exists... to perhaps focus a thread more explicitly on that point is helpful.

To reiterate a point made somewhat earlier, neither the numerical side NOR the descriptive side could ever claim to be the more truthful or more farsighted or, indeed, then more 'real'.

For my take on it, there will be times[in a historical and ongoing sense] when the numerical models are easy to describe in terms of everyday understanding but, as a practical necessity, there will be times when the required numerical complexity defies an easy explanation. It's a cyclical process.... an overwhelming complexity drives a need to bring some order with key descriptive insights... the insights then attract incorporation of other complications breeding complexity... and so on, round and round.
We might say it's frustrating for non-physicists/general public/etc during those times when a satisfying (or indeed, 'beautiful', might be a preferred term) description isn't available but thems the breaks.

Son Goku · 21-06-2005 10:04pm

MrAbc wrote:

To reiterate a point made somewhat earlier, neither the numerical side NOR the descriptive side could ever claim to be the more truthful or more farsighted or, indeed, then more 'real'.

I don't really understand what you mean by the numerical and descriptive sides. A mathematical equation relates mathematical objects which represent physical quantities.
I don't see how there is a conflict between the numerical and descriptive side of a physical relation or equation.

MrAbc · 21-06-2005 11:45pm

Sorry for any vagueness... for the numerical side v's descriptive side I was meaning to refer to situations where, on one hand, one might favour numerical accommodations which may seem rather inglorious but are highly successful v's on the other hand favouring more satisfying conceptual "pictures" that agree more with how you want the solution to feel but prove harder to find.
Obviously, it's all mathematical in working terms and the numerical accuracy is the last word in judgement, but there are, for example, always bound to be times where unwieldy mathematical complexity is resolved by the bigger implications of a new picture/description. Those choices might only arise at times of turbulent change, and it's more a matter of personal outlook, but some might not flinch at the most perverse mathematical directions while others might refuse to contemplate those same directions on the grounds of good taste :-) lol

nesf · 22-06-2005 2:01am

MrAbc wrote:

Sorry for any vagueness... for the numerical side v's descriptive side I was meaning to refer to situations where, on one hand, one might favour numerical accommodations which may seem rather inglorious but are highly successful v's on the other hand favouring more satisfying conceptual "pictures" that agree more with how you want the solution to feel but prove harder to find.

Ehm. They are the same thing basically. Just two different ways of expressing it

Oh and as to the devil's advocate thing. Hmmm. I didn't post "my thinking" much on this thread tbh. I was throwing about arguments i'd heard on physics for people to rip apart etc.

My own thinking, is, well, not something i feel a need to share tbh. I'm still not happy with it atm and want to think about it some more before I inflict it on others

Sapien · 22-06-2005 12:09pm

MrAbc wrote:

Sorry for any vagueness... for the numerical side v's descriptive side I was meaning to refer to situations where, on one hand, one might favour numerical accommodations which may seem rather inglorious but are highly successful v's on the other hand favouring more satisfying conceptual "pictures" that agree more with how you want the solution to feel but prove harder to find.
Obviously, it's all mathematical in working terms and the numerical accuracy is the last word in judgement, but there are, for example, always bound to be times where unwieldy mathematical complexity is resolved by the bigger implications of a new picture/description. Those choices might only arise at times of turbulent change, and it's more a matter of personal outlook, but some might not flinch at the most perverse mathematical directions while others might refuse to contemplate those same directions on the grounds of good taste :-) lol

I believe you refer to the distinction between theoretical modelling and heuristic modelling. The former is conceptual, where the mathematics involved correspond to real physical quantities, whereas in the latter the discrete mathematical terms generally have no relation to the real system. Theoretical models lend insight into the nature and causes of physical phenomena and have predictive power, while heuristic models only work over established ranges and tested parameters and are merey ad hoc mathematical constructs designed to replicate the appropriate input response. If this is what you mean then the answer is that one is Physics and the other is Engineering.

sean_0 · 23-06-2005 6:38pm

I'm not going to get into the whole philosophical thing but to give some straight answers to straight questions:

nesf wrote:

Does a person need to understand quantum to build a device using microprocessors?

The answer is yes and no. With the shrinking of gate dielectrics on MOSFETs, tunneling (a purely quantum effect) has become an issue in semiconductor devices. A little more shrinkage and classical effects like diffusion will be overtaken by quantum effects in ICs.

This means that to build a microprocessor knowledge of quantum effects is essential, to build a device that uses microprocessors maybe not, but it couldn't hurt right?

nesf wrote:

My point was that physicists talk about the "correctness" of their theories

To the best of my knowledge, physicist's never formally discuss the correctness of there theories, just the lack of contradiction. This is the essence of the scientific method. No good journal will publish claims like that, which are bound to be subjective since physical theories can never be absolutely proven correct (in the mathematical sense) as someone else here has already said.

That's my 2 cents anyway

Billy Kovachy · 05-07-2005 3:33pm

I remember reading before about how this lecturer used to get these letters from so-called physicists after he published a few papers on quantum physics. He developed a great way of cutting out crap like is mentioned in this forum from taking up his time. If there wasnt an equation or formula in the first page of the letter he would just throw it away.

planck2 · 05-07-2005 5:32pm

Somehow I agree

nesf · 05-07-2005 8:19pm

Billy Kovachy wrote:

I remember reading before about how this lecturer used to get these letters from so-called physicists after he published a few papers on quantum physics. He developed a great way of cutting out crap like is mentioned in this forum from taking up his time. If there wasnt an equation or formula in the first page of the letter he would just throw it away.

Crap? Please point me towards it....

Bear in mind that this thread isn't "normal" for this forum.

Please give examples and quotes when making nice big generalising comments like the above.

Plus, there is a huge, huge difference between letters being written for the attention of a scientific academic and a (as good as) anonymous bulletin board online.

Especially one that is open to lay people. If this was a closed academic board it would be extremely different.

Also, please bear in mind that mathematical forumlae are not easily expressed on here (in legible format). Yes, there are ways of doing it, but they are time consuming.

Strictly, this is trolling, but personally I think a little bit of trolling is good and I would be interested in hearing your opinion on this and for you to point out to me what you are unhappy with on this board. Not that I can make people post in a certain way but I might be able to nudge them in a certain direction if you present a good case.

Bear in mind that while I'm the moderator for here I will protect the right for lay people to post their queries on here. I will not stop them from doing so just to lend this board more academic kudos. I think that interaction with lay people is a responsibility and a requirement of scientists (in general terms here) and that it should be encouraged.

(Not that I'd give myself the label of "scientist". I'm not a labels kind of guy)

murphaph · 05-07-2005 10:36pm

kasintahan wrote:

As with all sciences - a law is merely something that we cannot currently disprove.

Remember, you cannot prove anything in science, only disprove.

Except in the one true science, mathematics. A theorem once proven, can never be disproved. Theories are just ideas.

I'm an engineer, not a scientist but we use the science of maths in so many places because it's the only truly reliable tool we have. Sure, we approximate things all the time because ideal conditions never exist in reality.

Errant11235 · 05-07-2005 10:56pm

murphaph wrote:

Except in the one true science, mathematics. A theorem once proven, can never be disproved. Theories are just ideas.

Of course a therom can be disproved! When ever a proof is created it can never be considered truly 100% right, because assumptions have been made by other theroms which act as the foundations of mathematics. It can be proved that (cosx)^2=1-(sinx)^2 ( just the first proof that came into my head!), but if for example, you could not prove 1+1=2 then that proof or any other for that matter would be fundamentally flawed. I think I read something which covered that topic in Fermats Last Therom but maybe I completely interpretted it the wrong way.

nesf · 05-07-2005 11:50pm

murphaph wrote:

Except in the one true science, mathematics. A theorem once proven, can never be disproved. Theories are just ideas.

I'm an engineer, not a scientist but we use the science of maths in so many places because it's the only truly reliable tool we have. Sure, we approximate things all the time because ideal conditions never exist in reality.

Maths is not a science per sae. It has nothing to do with the study of nature (ie what science is).

I'm not trying to diminish it here at all, I have a great deal of respect for maths and have many friends who are doing under/postgrads in it or who are lecturing it.

It's just, it's the study of logic. It's a lot closer to philosophy than it is to the sciences. Same as Engineering and the Sciences.

I'm about to fall asleep right now, long long day, little sleep, so I may have come across badly. I'll elabourate maybe after work tomorrow. Maybe.

murphaph · 06-07-2005 12:20am

Errant11235 wrote:

Of course a therom can be disproved! When ever a proof is created it can never be considered truly 100% right, because assumptions have been made by other theroms which act as the foundations of mathematics. It can be proved that (cosx)^2=1-(sinx)^2 ( just the first proof that came into my head!), but if for example, you could not prove 1+1=2 then that proof or any other for that matter would be fundamentally flawed. I think I read something which covered that topic in Fermats Last Therom but maybe I completely interpretted it the wrong way.

Can you name one theorem which was later disproved? They're called theorems because they're set in stone, derived from first principles. If they weren't set in stone they'd be just theories.

From wiki;

A theory is different from a theorem. The former is a model of physical events and cannot be proved from basic axioms. The latter is a statement of mathematical fact which logically follows from a set of axioms

And also

In mathematics, an axiom is not necessarily a self-evident truth but rather, a formal logical expression used in a deduction to yield further results.

So, the axiom you used above (1+1=2) is a good example of a self evident truth. If I have 1 apple and I am given another apple, I have two apples.

Here it is from Simon Singh (the Author of Fermat's Last Theorem!)

Part of the attraction for Wiles, Germain and the others was that mathematics, more than any other subject, is timeless. The Cambridge professor Godfrey Harold Hardy wrote in 1940: “Archimedes will be remembered when Aeschylus is forgotten, because languages die and mathematical ideas do not. Immortality may be a silly word, but probably a mathematician has the best chance of whatever it may mean.” Hardy was referring to the fact that mathematics relies solely on absolute, undeniable, logical proof, and therefore theorems, once proved, remain true forever.

On the other hand, scientific theories rely on fallible experiments, and as such are only probably true at best. For centuries the scientific establishment accepted Isaac Newton’s theory of gravity, but in the twentieth century the work of Albert Einstein showed that it was only an approximation to the truth - General Relativity has since become the dominant theory. Although Einstein’s theories appear to be true today, there is no guarantee that they will be considered true a century from now. However, Wiles’ proof of Fermat’s Last Theorem is valid today, and it will remain so until the end of time. Pythagoras’ theories about medicine and astronomy are no longer taken seriously, whereas Pythagoras’ Theorem regarding right-angled triangles is still considered a basic mathematical truth.

nesf · 06-07-2005 8:16am

Ahem.

Guys, interesting discussion etc, but if you really want to discuss the validity of maths and it's implications, at lenght with each other then go to the maths forum.

And axioms aren't self evident truths. They are unproveable foundations upon what the rest of the logical system is built. I can't remember the philosopher in question, but iirc it's impossible for a self contained logical system to prove itself.

If you wish to continue this debate, I'll split the thread and move it to maths so others will notice it and participate.

It's not that I don't think this is worthy discussion, I just don't think it should be in this thread or on this forum.

ecksor · 06-07-2005 3:03pm

You're thinking of Godel. "Self-evident truth" is a common, if nebulous, definition of axiom in the mathematical sense of the word. I think it's only relatively recently that people would start to see an axiom as being anything else requiring a more strict definition.

Billy Kovachy · 06-07-2005 3:17pm

Sorry forgot which issue of physics world i saw it. You label yourself a scientist thats nice. So what was you thesis on for your Phd. I really dont know what your looking for in this forum.A definition for science

"a human endeavor consciously aimed at acquiring knowledge about the world in a systematic and logically consistent manner, based on factual evidence obtained by observation and experimentation."

Or sorry how wrong approximations are in physics.Here is an example of how the got the speed of light through approximation and observation.

http://en.wikipedia.org/wiki/Light

Plus, our two main modern theories, namely quantum mechanics and general relativity disagree with each other over reality. They don't like each other and such.

They dont like each other. I can see it now General Relativity and Quantum Mechanics in Big Brother Reality not getting along. Poor Maxwell Equations stuck between them.Who is going to get evicted.

Now practically this is fine, GR is for big big things, QM is for very small things. So it's not that big a deal.

You should tell them that at CERN they will die laughing.

Physics spends all it's time playing catch up, and trying to alter and fix it's theories so they can explain the latest observed phenomena.

Physics is about observation to prove their theories. Physics is not against observations, which observed phenomena could you give me an example of the latest phenomena that you feel physics brakes down.

How can physics be wrong when it is deisgned to tell you what you already know?

So you know you will now ban me and you know ill be back.But you dont know how or when or why.

Here are crank mail concerning physicists.

http://www.nap.edu/openbook/0309084105/html/271.html

For some years he had been receiving “crank mail,” a drawback of the job and experienced by many other famous scientists throughout the world, especially physicists. However, by the late eighties Hawking was beginning to receive an inordinate quantity of bizarre letters spanning the entire spectrum of eccentricity. Correspondents ranged from amateur physicists in country villages proposing ridiculous solutions to cosmological questions, to religious extremists criticizing what they saw as the intrusion of science into sacred areas. Before long, a “cranks file” was set up at the DAMTP where the best examples of the genre

http://www.grisda.org/origins/22008.htm

In the 1950s while a graduate student at Stanford University, I was impressed by some guest lectures by William Pollard. He was both a practicing physicist (research and teaching) and a practicing Christian clergyman. His thesis was that to be a true physicist, one had to "enter the community" of physicists. Sometimes he would receive crank letters (for example, proposing a new perpetual motion machine) from people who obviously had not entered the community.

Ok some of them kept them

http://www.library.jhu.edu/collections/specialcollections/archives/inventories/rg04-030.html

13 Crank Letters, 1953-1959

http://www.talkreason.org/articles/magisteria.cfm#1

nesf · 06-07-2005 6:23pm

ecksor wrote:

You're thinking of Godel. "Self-evident truth" is a common, if nebulous, definition of axiom in the mathematical sense of the word. I think it's only relatively recently that people would start to see an axiom as being anything else requiring a more strict definition.

Sorry, wasn't quite awake this morning. Head wasn't working quite right and such.

I think there was a philosopher that proved it for "philosophical logic systems" before Godel did it for maths. But I might be just remembering it wrong.

nesf · 06-07-2005 6:44pm

Billy Kovachy wrote:

Sorry forgot which issue of physics world i saw it. You label yourself a scientist thats nice. So what was you thesis on for your Phd. I really dont know what your looking for in this forum.

Eh, I said I don't label myself as a scientist. Also that I'm not a labels kind of guy. I think they are far too subjective in interpretation. For example: Is a qualified physicist someone with a degree or a PhD? Both are equally valid choices (in some views), personally I wouldn't use the phrase at all. A physicist in my mind is anyone who studies and contributes to the subject (ie been involved in publishing academic papers).

I have not recieved a PhD and have never claimed to have done so. So please don't try and say that I have.

I could claim the "label" scientist because I've done experimental research in UCC under one of the senior lecturers there and published papers with him. I still don't claim that label though.

As for the rest, I think you've misread this thread.

This thread was me acting as a "devil's advocate". I stated quite clearly here and elsewhere that the posts I made in this thread were not my own views but simple things off the top of my head that people were supposed to argue against sucessfully. ie I went into this thread looking to lose this argument. I wanted people to use their heads and to rip my poorly stated and inaccurate posts to pieces. Constructive trolling if you will. I wanted to "open people's minds" by getting them to refute simple bad arguments against physics. I wish I could say that I could come up with good ones, but I'm not that talented.

I apologise if this wasn't clear to you.

Physics is about observation to prove their theories. Physics is not against observations, which observed phenomena could you give me an example of the latest phenomena that you feel physics brakes down.

Quite a lot of physics research is all about explaining that which doesn't fit into our present models.

Our models are good but they are not perfect. Anyone who has studied the subject at third level and above should know this.

So you know you will now ban me and you know ill be back.But you dont know how or when or why.

Why would I do that? The only people I ban from here are troublesome muppets. I've no issues with people disagreeing with me, especially when it's a case of them misreading a thread (as the case is here). Please, continue to contribute to here, and cheers for playing a valuable part in this thread. Just don't fall into the easy mistake of believing everything you read.

Or fall into the habit of judging posters on individual posts rather than their posting in general. Or that of judging a forum on the basis of a single thread.

Do you honestly think the admins here would allow me to mod this board if I held views like those I posted on this thread? Actually, don't answer that one...

Physics is inaccurate!

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