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I got into a debate with a friend about the meaning of physics and its purpose, he is the sort who will test you and if you get it wrong it somehow gratifies his own self-reflection and self-worth. That aside, I have loved physics since I got into it when I was at school, I had a great teacher who fostered that love and helped grow my appreciation for physics and ever since I have said to myself that I would one day go do my degree in physics. At the moment I have just finished my degree in computer security and forensics, I plan to study physics part-time hopefully in the next 5 years after I settle into permanent work in the software engineering field.

Anyway the conversation started with a question from him asking what temperature water boils at and what temperature does water freeze at. For the life of me I couldn’t remember, even as a general question most would know the answer, well that’s what we thought. For him this was a big disgrace and he continued to laugh and "then" call a friend to verify that I am being moronic. Of course he phoned our friend and pitched the same question, of which he neither knew the boiling point nor the freezing point of water. Regardless, for him he classed this as "true physics", but to me it could have been any random number for all I cared.

What he was trying to prelude to and was expecting as an answer was "it depends" and the dependency was altitude (from a documentary he watched). Of course I never got past that stage and all it became was a ridicule session. For me it didn’t matter I thought the true physics was understanding why water boiled in the first place. How exciting molecules or increasing the energy within water gradually increases its temperature and when the molecules become extremely excited water gets to its boiling temperature. Understanding this allows us to understand all the states of water (phases), from a solid (ice) to a liquid or to a gas (vapour, altho vapour is essentially two phases) in one, the phase change occurs via nucleation and growth - small liquid drops spontaneously form and evaporate, but if a drop is larger than some critical radius, it will continue to grow ('nucleates'). This is the most common phenomenon of a gas-liquid (or liquid-solid) phase transition. Of course I discussed this with him but he argued blind that "knowing" the boiling point of water was "physics" but to me that was essentially just a factoid. That the boiling point of water did not matter but understanding the process behind it did.

So I ask those of you in the community who was wrong or what physics trully is.

If we take the standard definition of Physics it is a natural science that involves the study of matter and its motion through space and time, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.

For me knowing the boiling temperature of water does not equate to understanding how water as a liquid, boils. Or the transfer of energy to change a liquids state occurs. It is simply just a consequence of the action or a "factoid" of the means in which we can reliably get the same testable results.

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closed as not constructive by dmckee Sep 13 '12 at 17:49

As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance.If this question can be reworded to fit the rules in the help center, please edit the question.

That's an interesting question. I'm not a physicist, but I would tend to agree with you. Specific knowledge is important if you are presenting academic work or engineering something, otherwise your level of knowledge on a subject is your business. If you're more satisfied knowing the process rather than having memorized facts, then you'll likely spend less time memorizing. Anyway, you're not alone. I'm the same. –  jakev Sep 13 '12 at 16:16
The question seems to be tailor made to violate the FAQ's stricture 'If your motivation for asking the question is “I would like to participate in a discussion about ______”, then you should not be asking here' and I am going to close it as such. That is not to say that it is not a good question, just not a good one for this site. Oh, and you can tell your friend that I said he's being a jerk. –  dmckee Sep 13 '12 at 17:49
I'm inclined to agree with what @dmckee said –  David Z Sep 13 '12 at 17:53

2 Answers 2

up vote 2 down vote accepted

I suspect this question is excessive philosophical and will be closed. However, while it's still open, I'd say Physics is the construction of mathematical models to make predictions about the real world.

The term "mathematical model" sounds complicated, but a mathematical model is just a set of one or more equations, into which you can feed measurements and from which you get predictions. An example most of us will have learned at school is Newtons Laws of Motion. This is a set of three simple equations. If you feed in initial positions and velocities Newton's laws allow to to predict the behaviour of (non-relativistic) systems into the future and indeed tell you what the behaviour was in the past.

Even the most abstruse Physics like M-theory is just the construction (and interpretation) of a mathematical model, though in the case of M-theory it isn't clear yet what the mathematical model is.

For info on a mathematical model to predict the boiling point of water see http://www.lsbu.ac.uk/water/models.html.

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I take it that you don't believe the question should be closed, though? –  David Z Sep 13 '12 at 17:19
Thats exactly how I look at it, and why I was so fascinated with physics when I was younger. Its really funny because I used Newton's 2nd law of motion after we had the debate and showed him, how using a mathematical model you could work out the weight of an object (force) or mass or gravitational acceleration (gravity), f=mg or in lamens terms W=mg. –  Garrith Graham Sep 13 '12 at 17:24
I think we have finally stumbled across an example of a question that is too philosophical and should be closed :-) I say this because the question can't be given a definitive answer. My answer is just an expression of my opinion and other contradictory answers could be equally valid. –  John Rennie Sep 13 '12 at 17:25
Can there be "other contradictory answers"? I think you answered with the real meaning of what physics truly is, at least the globally accepted meaning of what it is. –  Garrith Graham Sep 13 '12 at 17:33
@John in such cases it would be much appreciated if you vote to close the question. (It also helps if you don't post an answer to a question that you think should be closed, but that's less important) –  David Z Sep 13 '12 at 17:55

Your friend is simply anal and probably is one of those types that take pleasure in the attention they get by getting you all charged up by picking at your insides. Memorizing numbers isn't true physics, its knowing the process behind it. The number is simply a way of recording the result after you've understood the true physics. To put it another way, simply stating the number doesn't mean you understand the true physics. Understanding how that number was produced is.

In the end, who the f**k cares at what number water boils? Unless you're doing an experiment, then sure, okay. But you would think that you'd look it up before you do the experiment right? What's the big deal? The time it took for you to write this post is at least 50 times longer than it would have took to look up the number online!

If your friend is so practical in his everyday life, then just put the pot of water on a stove and put it on high heat, and simply wait. Then your water will boil, why does knowing the number even matter?

Final part of answer: Water boils at 100 degrees Celsius and freezes at 0 degrees Celsius. Covert them into Fahrenheit or to Kelvins if you will, but who cares? You can look up how to do that as well, that is if your not too lazy to, ...like your friend. You can look up how water boiling temperature changes with altitude online as well. I'm not gonna waste anymore time doing that for your friend.

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Lol QEntanglement, although I have to agree I think he was more preluding to the fact that the boiling point changed due to altitude and ofcourse he was very much correct. But he classed himself knowing that as "physics" when really the answer given by John Rennie sums up what physics trully is. –  Garrith Graham Sep 13 '12 at 16:50

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