Physics is inaccurate!

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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