004 : The Truth About Physics

Einstein Is Wrong

Gripping headlines for the last hundred years have often donned the title “Is Einstein Wrong?”. All the time concluding a firm “no”. There are two major issues with this discussion: Firstly, we all assume that Einstein is correct. We’ve had about a hundred years of experimental evidence to affirm this to be fair. Secondly, that we assume a hypothesis can be “correct”. There is, in fact, no way to “prove” that any physical hypothesis is “correct” or true (although we can falsify them). All we can ever say is whether a particular hypothesis agrees with observations or not. If it doesn’t, the hypothesis can be scrapped (or more often than not, altered by its author). If it does, then we can say with confidence that “this hypothesis agrees with observation”.

A Note On “Just A Theory”

This statement needs some unpacking. Often-times, when a hypothesis, that is a claim about the world, is spoken about in a dismissive manor, it is said that it is “just a theory”, implying that “don’t mind what that theory says, we can’t prove it anyway.” Hypotheses is really the concept being brought into question here. “Theory” in fact means the body of experimental results which corroborate the hypothesis. It’s all the evidence to suggest that the hypothesis is a good one.

We subscribe to these “theories” every day without realising, because we’re implicitly using our inductive reasoning. If you think gravity is “just a theory”, I challenge you to explain to yourself why you feel it necessary to not simply leap out of a four-story window to get where you’re going more quickly?

So What Is Correct?

A not so great scientist would say that “Einstein is correct.” A better scientist would say that “Einstein’s theories best describe what we are currently capable of observing.” It’s good to look at what’s happened historically at this point. Take Newtonian physics for example. At the time, they were ground-breaking; three laws of motion and a law of universal gravitation. In the framework scientists were working in, with the physical processes they could observe, Newton’s theories fit observation almost perfectly. Newton had to be correct. There was one outlier that became well known, however; the orbit of Mercury. It didn’t seem to match the theory, it was close, but not perfect. Einstein’s theories would later encompass and supercede Newton’s. So, what does this mean for Newtonian physics? Is it all wrong? Are we wasting time teaching these ideas?

In certain frameworks - those of low velocity compared with that of light speed - Newton’s physics is perfectly acceptable, and in fact favoured. NASA famously used Newtonian physics to get humanity to the Moon as the calculations are far simpler to work with, without losing accuracy. So what’s going on here? How can they both be correct? Therein lies the problem, our implicit wanting of things to be “correct”. We may never know if a physical theory is “correct”. What we can know, is whether what we observe in nature matches the predictions laid out in the theory in question.

Historical Progress

This has been the historical approach: Great minds would devise an explanation of the world around them in the language of mathematics. This would then be tested using the experiments available at the time. If the results fell within the margin of error then the hypothesis was verified. If the results fell outside this threshold, the hypothesis would be scrapped. Hypotheses would be continually tested, only needing one result to bring it into question and falsify it. The hypothesis would remain at the top until another great mind would come along with a more elegant theory that would not only describe what was known, but would also describe other yet to be explained phenomena. This has been the path of progress for the last several hundred years, and has led us to what we know today about the universe.

Conclusion

So in a somewhat negative sounding way, all physical theories are wrong, in that they do not perfectly describe the universe in totality. A more productive way to talk about physical theories is that they (the good ones) best describe our current observations of the universe. The current trend is that theories get better and better, more and more precise, describing physical reality more respectfully as the years go on. Could we eventually reach a theory that describes nature perfectly, and in totality? That is the current aim of many theoretical physicists in their search for an ambitiously titled “theory of everything”. Even if this was achieved, would it possess a proof? An undeniable truth about the universe? That we may never know. ▢