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Andrew Zimmerman Jones

Is Physics Real? - Part 1

By December 29, 2010

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Does physics actually describe reality or is it just a useful way of talking about how things happen?

This question often comes up when I speak about my recent book. People want to know if these curious properties of the universe proposed by theoretical physics - whether the experimentally-verified ones such as quarks and antimatter or the speculative ones such as strings and wormholes - are physical objects or just mathematical abstractions that happen to work out.

Unfortunately, the answer is unsatisfying to me as well as those who ask the question:

No one knows for sure.

Or, to put it more precisely, in many cases the physicists really don't care. The mathematical models which make up physics are such that physical objects such as particles are described as a mathematical entity. The mathematics make certain predictions, which is consistent with the existence of the particle, and those predictions are then tested.

In a sense, to theoretical physicists, the quark is the same thing as the mathematical model that represents the quark and to talk about whether or not the quark is "real" is kind of missing the point - that the model which uses quarks works to describe the physical system in question each and every time. (This is somewhat akin to the model-dependent realism discussed in Stephen Hawking's latest book.)

Physics is able to state what will happen in pretty much any situation that you come across in day-to-day life with an astounding degree of accuracy. (A point well illuminated a few months back by Sean Carroll at Cosmic Variance.) But in the realm of theoretical physics, things get much murkier. Predictions are made that are consistent with the known properties of the universe, but which often cannot actually be experimentally verified in any meaningful way.

Oddly, as I was contemplating these very issues, John Horgan tackled this subject over at the Scientific American blog with an intriguing comparison between anthropology and theoretical physics. He brings into question whether the work being done in theoretical physics is more akin to literary criticism (or even literature) than to traditional "hard" science.

Even those who embrace theoretical physics call the reality of some physical theories into question. In his 2007 book The Trouble with Physics, theoretical physicist Lee Smolin discusses two different types of theories:

  • Effective theories are useful at describing behaviors in reality, but do not describe the actual physical reality itself.
  • Fundamental theories not only describe the behaviors of objects, but also describe the actual physical reality of the situation.

In his book, Smolin uses these two descriptions to argue that string theory may be an effective theory, but that physicists should look elsewhere for a fundamental theory of nature.

One major problem with this tactic is that it's incredibly hard to determine whether a theory is effective or fundamental. About the only way to know for sure is to rule out its fundamental nature by showing that it's flawed. If it's flawed, then it can, by definition, just be a useful model of reality and not describe the real thing ... and therefore must only be an effective theory.

But I don't think it's wrong for science to embrace a theory which may only be effective, because really it's the efficacy of a theory that we care about. What does the theory tell us? What does it predict? What tangible components of reality does it allow us to understand or manipulate? This is really the point where science is most compelling, rather than just some abstract musings about how the universe "really" works.

Is physics real, then? I'll let that question be answered, in part, by the father of quantum mechanics, Niels Bohr:

It is wrong to think that the task of physics is to find out how Nature is. Physics concerns what we say about Nature.

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Comments

December 30, 2010 at 12:19 am
(1) 10dolphins says:

Is physics real?

When physics starts talking about strings vibrating in more than 3 dimensions and forming the basis of matter, we can safely say that physics is no longer real.

When math equations are used as models instead of mechanical models, we can say physics is no longer real.

When scientists think that if you shoot enough bowling balls at at a wall that one day the bowling ball will act as a wave and go right on through, we can say physics is no longer real.

I could go on, but I think you get the message.

December 30, 2010 at 12:24 am
(2) 10dolphins says:

One more thing:

To all you aspiring physicists out there, here is the solution to the physics puzzle.

The biggest flaw in current physics is the assumption that the electric charge is always conserved. Eg. An electron will always have the same charge.

In reality, a moving electron will gain a magnetic field at the expense of the electrostatic field as it speeds up. Vice versa as it slows down.

Once this theory is accepted, relativity can be thrown in the trash heap as well as quantum “theory” and scientists can move onto some really big discoveries.

December 30, 2010 at 1:06 am
(3) Nick says:

Plato has already dealt with this question, and Niels Bohr did homage to it in his statement. Physics is an inspired mathematical-lingusitic model using what has been described by experimenters to produce a description of what they will experience and describe in the future. Physics is a symbolic communication between sentient beings, in which the symbols relate past to future experience, the symbols bearing a loose correspondence to elements of experience. Reality, as experienced in total by the individual, is impossible to to communicate from one being to another, and in any case is only that individual’s experience, hardly REALITY IN ITSELF.

December 30, 2010 at 1:52 am
(4) Michael Donahue says:

When books on physics tell me that by compressing a jack-in-the-box I can increase its mass (through conserved energy) but the weight of my fingerprint (or the residue left by anything else used to do the compression) will be millions of times greater than the increase in mass resulting from the compression, we can say physics is no longer real.

When a popular theory (string theory) has, after nearly 40 years, generated no data and is in principle nonfalsifiable, we can safely say physics is no longer real.

When all we can say about dark matter and dark energy is that there is enough of it to balance all our equations, we can safely say physics is no longer real.

Physicists tell us that all objects fall at the same rate. Would a ping-pong ball and a piano it the ground at the same time? When physicists make generalizations that only apply under the most extreme conditions (e.g., a vacuum), we can safely say physics is no longer real.

December 30, 2010 at 3:18 am
(5) Jim says:

Unfortunately there appears to be a very large lack of understanding of what Physics even says or is. So people just make up things to fit their own world view and say that is what Physics says.

For the most part though, Physics is mostly about putting names on things. Most of those names are really just mathematical equivalents but they are still just names. Even the fundamental symmetries and their associated conservation laws are more about naming than anything else.

So, in a very large hand waving way, Physics is as real to ‘reality’ as your name is to you. It isn’t who you really are, but to almost everybody else in the world, it is who you are and it is what the rest of the rational world will call you.

December 30, 2010 at 6:07 am
(6) Steven Colyer says:

I sincerely hope Physics is real otherwise my television, cell phone, and my brother-in-law’s iPad wouldn’t work.

The knocks against it by some posters that precede my comment refer to speculative Physics at the cutting edge of Theory, that use more mathematics than they are or were familiar with in High School. Granted, not all Physics theories at the cutting edge will be correct, but pause and consider how far Humanity has come in so short a period of time. Each answer seems to breed four or more new questions, so Physicists shouldn’t worry about being out of a job anytime soon.

Excellent question, Andrew, thanks for raising it.

The quick answer is that Physicists use mathematical models to describe reality, so the more detailed question may be “Does Mathematics describe Reality”? The answer to that would be some does, some does not.

At the end of the day, Experiment will prove or disprove that which is currently cutting edge. We live in wonderful times, adventurous times, in this the most basic of Sciences.

December 30, 2010 at 7:45 am
(7) Oldman says:

It’s very heartening to find your comments, Andrew, and thanks for the Niels Bohr quote. I’ve said much the same in Physics Forums; see Post 20 in Marcus’s thread http://www.physicsforums.com/showthread.php?t=459520&page=2.

December 31, 2010 at 8:10 am
(8) Dr. Wiggly says:

Observations are bits of information about the physical universe. Theories are explanations of those observations.
One is not superior to the other nor are they interchangeable. I have X dollars in my bank account: that’s an observation. I theorize that the money is there because someone deposited a Christmas gift for me. If I ask around my friends, I may be able to discover whether the theory is true or not.
Simple, powerful, and very amazing to me.

January 3, 2011 at 11:57 am
(9) Ken Koskinen says:

The confusion arises due to the misunderstanding between two different parts of the process of science/physics. Science begins with what I call Speculative science i.e. theoretical physics and its aim is to get to what I call Solid Science i.e. experimentally/observationally confirmed theories.

Science needs the speculative process and some theories can even be perceived as being unreal or wild. Most theories or many will fall of the charts but some will make it into the confirmed or sold phase. Still some part of even the those that are highly respected can also remain unconfirmed or even be found to be flawed.

Those who would like to read an in depth discussion of the process of science can download my free essay “The Three “S’s” of Science & the Physics of Humpty Dumpty” at my website http://antspub.com . Simply dick on any “Downloads” button & chose the essay from the menu. It’s in the pdf format.

Ken

January 4, 2011 at 4:56 am
(10) yogendra chaturvedi says:

I think physics is the reality, because of it we r able to express , when it is expressed in mahematical language it is away of expressing , it is the technology tha can CHANGE THE THEORIES IN REALITY.

January 4, 2011 at 12:33 pm
(11) Norwin says:

Physics is our way of describing and explaining the physical world, and mathematics has proven to be the most effective (precise and easily manipulated) language in which to express the developed theories. Thus the question of reality is somewhat misplaced here. May be the question should be: Is Physics effective in describing and explaining the physical world?

February 12, 2011 at 4:09 pm
(12) Darrel says:

Firstly, at least to me, the main difference between the referenced so called effective theories and fundamental theories is 4D line of sight–or time. Many theories that were originally “effective” apparently became “fundamental” over time as more and more of its predictions and/or observations became confirmed. Math is real; math is a universal language; and, as far as I’m concerned, math IS fact. These now purely mathematical theories are definitely on to something as real as you or I… our technology that lets us define what our “observable” universe is simply needs to catch up. As the scope of our perception changes and expands over time (if we make it as a species), the line between “effective” and “fundamental” referencing currently more esoteric theories will certainly fade… of course, new “effective” theories will most certainly replace these!

Secondly, I thought Max Planck was the father of quantum mechanics?!

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