The Joy of Science

Jim Al-Khalili

• Publisher: Princeton University Press
• Year: 2022
• ISBN:
  9780691235660
• Topic: Philosophie
• Subtopic: Philosophie et éthique en sciences

Quantum physicist, New York Times bestselling author, and BBC host Jim Al-Khalili reveals how 8 lessons from the heart of science can help you get the most out of life Today's world is unpredictable and full of contradictions, and navigating its complexities while trying to make the best decisions is far from easy. The Joy of Science presents 8 short lessons on how to unlock the clarity, empowerment, and joy of thinking and living a little more scientifically.In this brief guide to leading a more rational life, acclaimed physicist Jim Al-Khalili invites readers to engage with the world as scientists have been trained to do. The scientific method has served humankind well in its quest to see things as they really are, and underpinning the scientific method are core principles that can help us all navigate modern life more confidently. Discussing the nature of truth and uncertainty, the role of doubt, the pros and cons of simplification, the value of guarding against bias, the importance of evidence-based thinking, and more, Al-Khalili shows how the powerful ideas at the heart of the scientific method are deeply relevant to the complicated times we live in and the difficult choices we make.Read this book and discover the joy of science. It will empower you to think more objectively, see through the fog of your own preexisting beliefs, and lead a more fulfilling life.

1

SOMETHING IS EITHER TRUE, OR IT ISN’T

How many times have you gotten into an argument with a friend, colleague or family member—or, even worse, with a stranger on social media—and stated what you thought was a clear-cut fact, only to hear the response, “Well, that’s your view”, or “That’s one way of looking at it”? These responses—often polite, sometimes aggressive—are examples of the insidious and disturbingly common phenomenon of ‘post-truth’. Defined by the Oxford Dictionary as “relating to or denoting circumstances in which objective facts are less influential in shaping public opinion than appeals to emotion and personal belief,” post-truth has become so prevalent that the term was ‘word of the year’ in 2016. Have we moved too far away from objective truth, to the extent that even proven facts about the world can be conveniently dismissed if we don’t like them?

Even while we find ourselves in a postmodern world of cultural relativism, the internet, and social media in particular, is driving society towards ever-increasing polarisation of opinions on all manner of cultural and political issues, and we are expected to pick sides, with each one making a claim on the ‘truth’. When a blatantly untrue assertion, motivated by a particular ideological belief, holds sway over an undeniable fact or over knowledge supported by reliable evidence, we see the phenomenon of post-truth politics in action. On social media, it is most often seen linked to conspiracy theories or in the pronouncements of populist leaders or demagogues. Sadly, this irrational way of thinking has infected many people’s attitudes more generally, including their views towards science, and we often see claims on social media that opinion is more valid than evidence.

In science, we use different models to describe nature; we have different ways of building up our scientific knowledge, and we regularly create different narratives depending on what aspects of a phenomenon or process we want to understand, but this is not the same as saying that there are alternative truths about the world. A physicist like me tries to uncover ultimate truths about how the world is. Such truths exist independently of human feelings and biases. Gaining scientific knowledge is not easy, but acknowledging that there is a truth out there, towards which we can strive, makes our mission clearer. Following the scientific method, critiquing and testing our theories and repeating our observations and experiments, ensures that we can get closer to that truth. But even in our messy everyday world, we can still adopt a scientific attitude to reach the truth of a matter—to help us see through the fog. We must therefore learn to spot and weed out what are ‘culturally relative’ truths or ideologically motivated truths and examine them rationally. And when we encounter the sorts of falsehoods referred to as ‘alternative facts’, we must remember that those who advocate them are not trying to present a believable narrative to replace an original fact, but merely to create plausible levels of doubt to suit their ideologies.

There are many situations in everyday life in which acknowledging the existence of objective truth and taking steps to seek it out can prove to be of far greater value than convenience, pragmatism or self-interest. How then do we get to this truth—not my truth or your truth, not conservative truth or liberal truth, not Western truth or Eastern truth, but the truth about something—however trivial? And to whom can we turn for help? How can we be sure of a source’s honesty and objectivity?

Sometimes it is easy to see why a person, group or organisation holds a particular view, for they may have a particular motive or vested interest. For example, if a representative of the tobacco industry tells you that smoking is not really harmful and that the health risks are exaggerated, then you should rightly dismiss what they say. After all, they would say that, wouldn’t they? But all too often people mistakenly apply this same reasoning when they don’t need to. For example, if a climatologist says that Earth’s climate is changing rapidly and that we need to modify our lifestyles to prevent catastrophic consequences, a climate change denier will often counter with, “Well, of course they would say that.… They’re in the pay of ‘x’ ” (where ‘x’ could be an environmental group or green energy company, or just perceived liberal academia).

I am not denying that in certain cases this cynicism may be justified, for we can all think of examples of research that is funded for ideologically driven or profit-driven motives. And we must also be wary of so-called data dredging—also known as ‘p-hacking’—whereby analysis of data is misused deliberately in order to find something that can be presented as statistically significant, then only reporting those cherry-picked conclusions.⁶ I will say more about this in chapter 6 when I discuss confirmation bias. But these inevitable biases notwithstanding, a suspicion of science or denial of its findings often occurs because of a misunderstanding of how science works.

In science, an explanation that has survived the scrutiny of the scientific method can become an established fact about the world, adding to our cumulative scientific knowledge … and that fact is not going to change. Let me give you my favourite example from physics. Galileo came up with a formula that allowed him to calculate how quickly an object falls when dropped. But his formula was more than ‘just a theory’. We still use it over four centuries later because we know it to be true. If I drop a ball from a height of five metres, it will fall for one second⁷ before it hits the ground—not two seconds or half a second, but one second. This is an established, absolute truth about the world that is never going to change.

In contrast, when it comes to the complexity of individual human behaviour (psychology) or the way humans interact within society (sociology) we find, inevitably, that there is more nuance and ambiguity. This suggests that there can indeed often be more than one ‘truth’, depending on how we see the world. This is not the case when it comes to the physical world, such as the time it takes for a ball to fall to the ground. When natural scientists, such as physicists, chemists or biologists, state that something is either true or it isn’t, they are not talking about complex moral truths, but about objective truths about the world.

To show you what I mean, I will present a list of randomly selected facts, each of which is either true or false. They are not debatable or subject to opinion, ideological belief or cultural background, and we can use the scientific method to confirm or dismiss each of them. The conclusions we draw about them will also not change over time. Some readers may wish to dispute a few—maybe by saying something like, “But that’s just your opinion”, or “How can you possibly be so certain? I thought the scientific method always left room for doubt”, and so on. However, the items on this list are meant to show that while we must always be open to new ideas and explanations in science and that what we once thought to be true may turn out not to be so once we gain a deeper understanding, we do know some things for sure. We really do. The reason I am being so bullishly confident is because if science is wrong about any one of the items in the list below, then the whole edifice of scientific knowledge would need to be pulled down and rebuilt. Even worse, all the technology that relies on that knowledge would have been impossible to create. And I find that so exceedingly unlikely that I am as near to certain about them as one can be in science. Anyway, here’s the list:

1. Humans have walked on the Moon—True
2. The Earth is flat—Not True
3. Life on Earth evolved through a process of natural selection—True
4. The world was created about six thousand years ago—Not True
5. Earth’s climate is changing rapidly, mainly due to humanity’s actions—True
6. Nothing can travel through space faster than the speed of light in a vacuum—True
7. Give or take, there are roughly seven billion billion billion atoms in the human body—True
8. 5G masts contribute to the spread of viruses—Not True

For each of these examples, I can provide mountains of evidence to support their truth or falsehood. But that would be very boring. On the other hand, what is more interesting to explore is why some people might disagree with me if, I would argue, they are not thinking scientifically. Take the idea of falsifiability. The philosopher Karl Popper stated that we can never prove a scientific theory to be correct since that would require us to test it in every conceivable way, which is impossible. However, a single counterexample can prove a theory false. You’ll remember this from the example of the white swans I mentioned earlier. Popper argued that the idea of falsifiability was a crucial feature of the scientific method. However, a weakness of his argument is that the counterexample offered—for example, an experimental result—might itself be false. Maybe the brown swan that refutes the claim that all swans are white is simply caked in mud. This was the case in the famous faster-than-light neutrinos experiment I mentioned in the introduction. Unfortunately, it is precisely this loophole that conspiracy theorists fall back on in denying the validity of any evidence against their pet theory—whether it is the claim that the Moon landings were a hoax, or that the Earth is flat or that the MMR vaccine causes autism in children. They will forever claim that the evidence against their theory is itself false. This is a classic example of misusing one of the tools of the scientific method—by denying and rejecting any evidence that falsifies one’s theory, never offering a rational scientific reason for that rejection, nor ever stating what form of evidence one would demand as sufficient to falsify one’s theory.

The opposite scenario is even more fascinating: when something factually true is denied in spite of overwhelming evidence. This denial can take several forms: the most basic is called literal denial, and it means just that: a simple refusal to accept or believe the facts. Then there is interpretive denial in which the facts are accepted but interpreted differently to fit in with the person’s ideology, culture, politics or religion. Finally, and most interesting of all, is implicatory denial, coined by the sociologist Stanley Cohen.⁸ This states that if A implies B and I don’t like B, then I will reject A too. For example, the theory of evolution implies that life evolves randomly and without purpose. But this goes against my religious beliefs, so I reject evolution theory. Or: acting to stop climate change requires me to change my lifestyle, which I am not prepared to do, therefore I reject the claims that the climate is changing or that we can do anything about it. Or: to stop the spread of the Covid virus we must follow Government advice, stay at home and lose income, and wear face masks when out in public. These restrict my fundamental freedoms and therefore I reject the scientific evidence that calls for such actions.

Of course, there is a world of difference between hard scientific facts and the sorts of messy, vague truths we encounter in everyday life. When a particular statement about something is embedded within the complex morass of beliefs, feelings, behaviours, social interactions, decision-making or any of the other million issues we encounter and debate, then it can often be more complicated than simple black and white. This does not mean that the statement is untrue, but rather that, by itself, it may not be entirely valid in all situations. Even a simple statement can be both true and false depending on the context; it can be true in one situation, but not another. In some cases, the same can be true in science too. When I stated the fact that a ball dropped from a height of five metres will hit the ground after one second, I failed to mention the context in which it is a true fact: namely that this only applies on Earth. A ball dropped from five metres above the surface of the Moon will take almost two and a half seconds to hit the ground because the Moon is smaller than the Earth and so has a weaker gravitational pull. It’s the same scientific formula that we use—that is an absolute truth—but the numbers we plug in to get the answer are different. Sometimes, even scientific truths have to be put into context.⁹

A simple truth can also be expanded to include more information and give us a deeper understanding, which can take it in a different direction. For example, the scientific fact about how long a ball takes to hit the ground, whether on Earth or on the Moon, is explained by Newton’s law of gravity. But we now have a deeper and more profound picture of the nature of gravity thanks to Einstein’s theory of relativity. While the time taken for a ball to fall is a fact (given the context) that will never change, we now have a better understanding of what is going on. Newton’s picture of gravity as an invisible force pulling the ball to the ground has been replaced with Einstein’s picture of masses bending s...