Sabine Hossenfelder's Blog, page 86

What is Reductionism?

Last week, we spoke about emergence, this week, we will speak about the opposite: Reductionism. Reductionism, loosely speaking, is the idea that you can understand things by taking them apart into smaller things. This definition of reductionism, as we will see, is not quite correct, but it’s not too far off. Before we get to the details, however, a few words about how enormously important

What is emergence? What does “emergent” mean?

The word “emerging” is often used colloquially to mean something like “giving rise to” or “becoming apparent”. But emerging, emergent, and emergence are also technical terms. So, today I want to explain what physicists mean by emergence, which is also the way that the expression is often, but not always, used by philosophers.





Emergent broadly speaking refers to novel types of behavior in

What is emergence? What means emergent?

The word “emerging” is often used colloquially to mean something like “giving rise to” or “becoming apparent”. But emerging, emergent, and emergence are also technical terms. So, today I want to explain what physicists mean by emergence, which is also the way that the expression is often, but not always, used by philosophers.





Emergent broadly speaking refers to novel types of behavior in

It's the end of the world as we know it, coronavirus edition [I've been singing again]

Are dark energy and dark matter scientific?

I have noticed that each time I talk or write about dark energy or dark matter, I get a lot of comments from people saying, oh that stuff doesn’t exist, you can’t just invent something invisible each time there’s an inconvenient measurement. Physicists have totally lost it. This is such a common misunderstanding that I thought I will dedicate a video to sorting this out. Dark energy and dark

Unpredictability, Undecidability, and Uncomputability

There are quite a number of mathematical theorems that prove the power of mathematics has its limits. But how relevant are these theorems for science? In this video I want to briefly summarize an essay that I just submitted to the essay contest of the Foundational Questions Institute. This year the topic is “Unpredictability, undecidability, and uncomputability”.


Take Gödel’s theorem. Gödel’s

Coronavirus? I have nothing to add.

I keep getting requests from people that I comment on the coronavirus pandemic, disease models, or measures taken to contain and mitigate the outbreak. While I appreciate the faith you put into me, it also leaves me somewhat perplexed. I am not an epidemiologist; I’m a physicist. I have nothing original to say about coronavirus. Sure, I could tell you what I have taken away from other people’s

Essays, Elsewhere

Just a brief note that Tim and I have an essay up at Nautilus

How to Make Sense of Quantum Physics
Superdeterminism, a long-abandoned idea, may help us overcome the current crisis in physics.
BY SABINE HOSSENFELDER & TIM PALMER

Quantum mechanics isn’t rocket science. But it’s well on the way to take the place of rocket science as the go-to metaphor for unintelligible math. Quantum mechanics,

Is Gravity a Force?

I was sick last week and lost like 10 pounds in 3 days, which brings up the question, what is weight?


Weight is actually the force that acts on your body due to the pull of gravity. Now, the gravitational force depends on the mass of the object that is generating the force, in this case, planet Earth. So you can lose weight by simply moving to the moon. Technically, therefore, I should have

How good is the evidence for Dark Energy?

I spoke with Professor Subir Sarkar from the University of Oxford about his claim that dark energy might not exist and the so-called Hubble-tension isn't.