This is an extract from the OPIP book. It follows the chapter in which A(lice) and B(obby) discussed why outsiders—as opposed to the experts—are sometimes in a better position to bring the paradigm shifts that are required for progress.
B: Another reason why outsiders may have an edge is that they are not as prone to fall into established thinking traps as those who’ve been working in the field for a long time. It’s much easier to spot and question assumptions if you haven’t based your work of the last 10 years on them.
A: What’s wrong with using assumptions?
B: It’s a funny thing with those assumptions. On one hand, they’re the daily tools of physicists. We can only make progress if we postulate certain assumptions and see where it gets us. On the other hand, they’re traps. Base your work on incorrect assumptions, and you can be as brilliant as you want—demonstrate your intelligence through intricately logical deductions on a higher level, resolve inconsistencies, and present impressive conclusions. But it will all be in vain.
A: It’s like taking a wrong turn at some point and going down a long road you don’t know is a dead end.
B: Right. This challenge applies to any discipline that deals with assumptions. Even in everyday discussions, if you’re arguing based on terms that are not clearly defined, the debates can go on for ages. You can write books about it and dedicate your life to it. And again, it’s all futile (except that you may sell a lot of books). Philosophical discussions are frequently based on this error.
A: So the essence of this is that we spend a lot of time in vain?
B: Yes, and it’s important to appreciate how much of a practical issue this is. Time is limited and precious. I believe the actual reason why we don’t have more progress is because time was wasted in some way. I’m sure there are plenty of potential Einsteins out there. However, they remain untapped potentials because they spend time on the wrong problems, whether in physics or otherwise. I’ll elaborate on identifying the right problems later.
A: How can we avoid incorrect assumptions?
B: First of all, the assumptions should be clear at all times. If you ask physicists for the assumptions they base their work on, and you don’t get an immediate answer, it spells trouble. It means they are not fully aware of them, and they are likely working on shaky grounds.
A: Do you have an example?
B: It applies to any theory, even to those that look straightforward. If you investigate why an apple falls to Earth, it already contains at least three assumptions: that there is an apple, that there is Earth, and that the apple falls to Earth. Who knows, if Newton had looked at it this way, maybe he would have realized that the third assumption isn’t universally true and that it could also be seen as the Earth accelerating up toward the apple?[1] Then we wouldn’t have needed Einstein to tell us that.
A: I’m quite sure Newton would not have come to that conclusion. But I get your point. What else?
B: Assumptions often start very early. Every visualization—which means nothing other than using our old model in which objects move through space while time elapses—already contains several assumptions. I’m not saying you shouldn’t visualize; I’m just saying be aware that it contains assumptions.
A: What about assumptions that are very likely correct? I mean the things we can be quite certain about.
B: Like what?
A: For example, as certain as we’re talking right now.
B: There is no “we,” there is no “talking,” and it’s not “now.” And a lot of what we’re saying isn’t “right.”
A: You’re contradicting yourself. You just also used “we” and “saying.”
B: I just told you that not everything I say is right.
A: I think you’re trying to confuse me. In any case, you know what I mean. I’m referring to the assumptions that are very likely true, as far as we can tell. What about using those?
B: That’s better, but still be skeptical. Not only because they may turn out to be incorrect, but also because just a few “very likely correct” assumptions can still send you down the wrong path. If you rely on three assumptions—most of the time it’s many more—and each of the assumptions is correct with an 80% probability—most assumptions are not anywhere close to that—even then, you’re again on the wrong track with almost a 50% probability (1-0.8*0.8*0.8).
A: Right. Conclusions?
B: Put all your assumptions down on paper. For some theories, if you then take a step back, and look at the pyramid of assumptions, it will dawn on you that this is probably not the best way to spend your time. At that point, the theory that uses those assumptions hasn’t been refuted yet in the slightest. However, it will be obvious that you should prioritize it lower and focus on theories with fewer assumptions. If you want to do foundational physics, then actually do foundational physics, not high-up-in-the-air physics with the likely outcome of the house of cards collapsing due to wrong assumptions.
A: You’re done with your rant against assumptions?
B: No. Another sneaky aspect of assumptions is that they are often hidden, not always standing out as separate units of thought. For instance, you may think that you leave all the assumptions of the macroscopic world behind when analyzing the microscopic world. But in fact, the microscopic world still includes many old assumptions as it’s only a “zoomed-in” or “chopped up” version of the macroscopic world.
A: Okay, so that’s another case where our expressions carry assumptions that are based on our old understanding.
B: Yes. Another example: It’s said that an electron has “mass.” That’s so old world. It sounds like it has to step on a scale to measure its weight.[2] What if the scale shows more than expected—does the electron then have to go on a diet?
A: You’re talking nonsense now.
B: I agree, but only if you stay at the level of the words’ literal interpretation. Try to get the underlying meaning of it. The point is that we’re using expressions and ideas from our everyday world that carry a lot of assumptions.
A: Maybe, but “electrons going on diets”? That’s ridiculous.
B: True, but let’s think about it… what makes the “diet”-comment so ridiculous? It’s because it so obviously doesn’t apply to this situation at all, right? That’s exactly my point; those everyday concepts don’t make any sense if applied to the microscopic world. At least I say it in jest; you are the one—if you believe that electrons have mass in the classical sense of weight—who is exhibiting much more “diet-thinking” than I do.
A: I think current physics is well aware that those concepts stop applying at a certain scale.
B: Yes, but it’s still called “mass.” That may cause confusion and lead people astray. Of course, you can keep calling it “mass,” quickly followed by a clarification such as “it’s not actually mass how we got to know it.” But this approach always carries the risk of misunderstandings.
A: I get what you mean, but I’m struggling to understand what you suggest. We need those concepts to describe our world—and we do so quite successfully, if I may add. If you have a better idea, I’d love to hear it.
B: I don’t have any better proposal, and it’s not about that now. It’s about developing an understanding of where we may go wrong, as we are working with implied assumptions. Whatever the new solutions will be, they will not be described with those terms, as those imply the assumptions of our old world.
A: Maybe we can agree that we should always retain a certain level of healthy skepticism regarding the expressions we use.
B: Right. And it’s not only about those “static” expressions. Assumptions also sneak in unnoticeably when we’re describing the dynamic behavior of our world. For example, you may observe objects moving slowly, then accelerate faster and faster, implying that this pattern can go on forever. You may not even consider the possibility of a limit. Realizing that such an extrapolation is an assumption in itself is easy to overlook.
A: And as you stated earlier, it should also make us skeptical that infinity has never been observed in practice. [Here Alice refers to the earlier discussion where Bobby argued that the concept of infinity is a human invention]
B: Yes, any concept that has never been observed has a smell of having been invented by humans, even if—or especially because—it feels so natural and goes unquestioned. And if, as in the case of infinity, there is no possible way to prove it in practice, it should be the nail in the coffin of such concepts. Instead, those zombies are happily walking through the field of physics, blocking the way for progress.
A: From where did you get the idea that “If it cannot be proven, even not in principle, why assume it’s real?”
B: I didn’t come up with it. I first encountered it when learning about Heisenberg’s uncertainty principle, which asserts that one cannot simultaneously determine both the position and momentum of a particle with absolute precision. If you shoot a photon at an electron to determine its position, you give the electron a kick that will change its momentum in an uncertain way. You could use lower energy photons that will have a lesser effect on the momentum (i.e., it will be clearer what momentum the electron has), but then lose precision in determining the electron’s position. At first, this might appear as a mere experimental limitation. However, Heisenberg deduced that if it’s impossible, even in principle, to determine both the exact position and momentum of a particle, why assume it has those characteristics at all? He inferred that concepts such as position and momentum stop making sense at a certain level. I’ve always been fascinated by this perspective and believe that it may apply to other areas in physics as well.
A: You mean not only to quantum physics?
B: Yes. Relativity theory also touches on similar principles. One example is Einstein’s famous elevator thought experiment. The person in the windowless elevator cannot conduct any experiment that would tell him whether the force he’s experiencing is due to the elevator accelerating or because the elevator is standing on the surface of a planet that exerts gravity. If that is true, then those two scenarios are the same.
A: They’re not the same. In one case he’s in an accelerating elevator, in the other, he’s standing on the ground.
B: That’s the common sense interpretation of it. But we should be skeptical of our common sense, especially as it hasn’t brought us much progress recently. We have to adjust our understanding of those two scenarios, and question fundamental concepts, such as matter, space and time, so that those two cases logically appear as the same to us. This equivalence principle, by the way, is a unification too (of inertial and gravitational mass). [Here Bobby refers to the earlier discussion which gave a logical explanation for why there is unification in physics]
A: We’re getting a bit off-topic. Let’s get back to assumptions. The conclusion is: always know your assumptions?
B: Yes, and don’t be shy to spend significant time understanding your assumptions deeply. Dedicate as much time to understanding them as you do to deriving conclusions based on those assumptions. This is a general principle, not only applying to physics. Some decisions in our lives have the potential to cause major damage, yet they often don’t feel significant and are made hastily, without much thought. For instance, some people work a long time to save money and then make quick decisions on how to invest it, risking losing much of it again. Hence, it’s sometimes suggested to spend as much time in making such investment decisions as it took to earn the money in the first place. While this might be a little too extreme, the basic idea behind this principle is a wise one.
A: Do you have any other suggestions for physicists apart from doing a review of their theories for assumptions?
B: “Doing a review” sounds a bit like it’s a one-time exercise for existing theories. While it’s important to do so, mere reviewing isn’t enough. It should be a guiding principle for how new theories are developed, always striving to take the path of least assumptions. It reminds me of security in the software industry. Web applications should be checked for vulnerabilities by security researchers—yes. However, even more important is that the developers who code websites already have security in mind, so that no issues arise in the first place. A good developer, even if not a security expert, should have security in their DNA. A physicist should have a very good feeling and awareness in their DNA regarding which assumptions their theories are based on.
A: Okay, so physicists should constantly be aware of the assumptions they make.
B: Yes. There should always be a conscious thought process when deciding to bring an assumption on board.
A: That also implies declining a lot of assumptions?
B: Yes, and that’s not always easy. The tantalizing prospects we see on the other side often make us rush across a shaky bridge without checking its stability. It requires a lot of character and self-control to resist that temptation. By the way, this mindset not only prevents us from going down the wrong path, but also fosters humility by vividly reminding us that we can always be wrong. That should be the scientific spirit, no? I sometimes feel that it gets a bit lost when physicists claim that the world is like X or Y.
A: It’s probably good to keep in mind that we can never know for sure.
B: Right. By the way, that’s an aspect I like about Subjectivity Theory [A theory discussed earlier in the book], independent of whether it’s right or not. It takes this principle to the extreme. The basic idea is the following: we’ve observed that humility is important for progress in science. So why not take this to the maximum and see where it leads us? And what is the maximum? It’s good old Socrates again: “I know that I know nothing.” Why not accept that we will never learn “the truth”? I understand it’s not easy, as it implies an ultimate resignation. But perhaps such humility is needed to make progress.
A: And not all physicists exhibit such humility?
B: Many don’t. You can often tell by the way they talk; if they speak with a tone of certainty, it already makes me very skeptical. I assume some do because they learned that they are more convincing this way. That’s probably true. But it goes against the scientific spirit.
A: Where else can we observe a lack of humility?
B: The current scientific process in physics often goes like this: physicists propose a theory A that they consider to be true. Then it gets disproven. So they adjust it to theory B, which they then present as “now this has to be right.” But of course, it gets disproven again. This pattern continues. It’s like getting smacked in the face by nature every day. Some physicists seem to enjoy this.
A: Isn’t that the scientific method? Don’t you also embrace it?
B: Actually, you’re right, I enjoy it too. Getting disproven continuously and adjusting the theories accordingly will always be a core principle to get new insights. Hence, let me adjust a little what I just said…
The book continues by analyzing the importance of embracing refutations. Buy it now.
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[1] For a good video explanation, watch Gravity Is Not a Force.
[2] For the record: mass and weight are distinctly different concepts in physics. Mass is, simply put, a measure of how much “stuff” an object comprises and how it responds to forces (inertia), remaining constant regardless of its location. On the other hand, weight is the gravitational force exerted on that mass. It can vary based on the gravitational field of the location. For example, while an object’s mass remains the same on Earth and the Moon, its weight would be less on the Moon due to the weaker gravitational field.
