Sabine Hossenfelder: Backreaction

When you try to combine quantum physics with Einstein’s theories, you quickly run into some pretty serious problems. The biggest is that causality – the order in which events occur – becomes uncertain as the rest of quantum physics. A group of physicists have leveraged that uncertainty, and are now claiming that they can send messages to the past using quantum mechanics. It’s not as crazy as it

Life on Earth has a peculiar property – many biological molecules have a handedness, or a “chirality.” DNA twists one way and not the other, and all the rest of life must fit to this reality. In a new paper, researchers say they know why: It all comes down to physics! The answer could change our understanding of life across the universe. Let’s take a look.

Current AI technology seems to be making decent progress despite concerns about it slowing over time. But while AI is slowly becoming more “intelligent”, the industry is running into another problem: energy supply. Let’s take a look at why energy is quickly becoming a major problem for progress in AI.

According to predictions from weather organizations across the planet, a super El Niño weather event is likely to begin over the next few weeks. It’s predicted to drive up temperatures across the globe, bringing increased chances of heatwaves, drought, wildfires, and even famines – plus, this year’s El Niño is likely to be stronger than usual, making those effects worse. Let’s take a look.

Scientists say that they’ve just detected a massive cloud of gas some 3 billion lightyears in diameter, floating in space roughly 7 billion light years away from us. This is pretty cool, but the problem is that our current models of the universe say that it (and other massive structures like it) just shouldn’t exist. Let’s take a look.

Investors across the globe are putting record amounts of money into cold fusion technology, which promises to bring us nuclear fusion without the need to create miniature stars on Earth. But are these companies actually delivering, or is this just another speculative tech bubble? Let’s take a look.

Physicists have been trying to reconcile the differences between Einstein’s theory of spacetime and our observations of quantum mechanics for almost a century. One way that they’ve attempted to do this involves theories that treat space as one-dimensional at very short distances. In a recent paper, physicists claim that they’ve solved a major problem that’s plagued these theories for decades.

The company Casimir Inc promises "unlimited power" from the vacuum by using the Casimir effect. Here is why you shouldn't believe what they say.

Generating electricity via nuclear fission is a great idea, at least in principle. But the risk of nuclear meltdowns causing mass destruction and long-lasting contamination isn’t appealing. Luckily, a crop of companies are looking to solve this problem by creating subcritical nuclear reactors, which generate power without ever making runaway nuclear reactions possible. Let’s take a look.

That life might have come to earth traveling through outer space used to be a fringe theory called ‘panspermia’. But in the past decade or so, we have seen an interesting shift in how scientists regard the idea. Let’s take at one new study that might support ‘panspermia,’ as well as other facts that support the theory.

I looked at the cases of vanishing scientists in the US and have to admit... it's very odd. Here are my thoughts.

Over the past few years, China has invested heavily in its renewable energy sector. In 2025, the country built enough energy capacity to power Germany twice over, with the vast majority of that capacity coming from solar and wind power. But while it’s invested in green energy, Beijing has also continued building coal and nuclear power plants – this dichotomy has led to some people hailing China

To this day, researchers don’t fully understand quantum physics. But in a new paper, physicists from MIT say that that’s okay – because the phenomena we use quantum physics to explain can actually be understood using classical physics. Really? Let’s take a look.

The biggest open problem in the foundations of physics is that Einstein’s theory of gravity, General Relativity, does not cooperate with quantum mechanics. Physicists have tried to solve this issue by coming up with a theory of quantum gravity, but those theories fall apart when you need them most – inside of black holes and at the Big Bang. Recently, though, physicists published a new

Natural selection allows animals – including humans – to slowly adapt to their environments over tens of thousands of years. Unfortunately for us humans, we’re quickly changing our environments and lifestyles, building sprawling cities and working at desks for 10 hours a day. According to a new paper, we now have good evidence that humans are no longer fit to live in the world we’ve created.

According to the New York Post, the U.S. used a “long-range quantum magnetometer” that can “find the electromagnetic fingerprint of a human heartbeat” in its Easter weekend operation to rescue an F-15 weapons systems officer. But does the U.S. actually have the crazy quantum surveillance capabilities that the Post claims it does? Let's find out.

Mathematical functions are built from operations, which are used to perform the calculations that make science and technology run. But what if we could do away with multiplication, addition, subtraction, and division? That’s what one mathematician has done in a new paper – he claims that everything in mathematics can be done with just one operation, which he’s calling “eml”. Let’s take a look.

MOND (Modified Newtonian Dynamics) is a theory of gravity that explains the physical phenomena we observe in galaxies with surprising accuracy, but it falls apart when it’s applied to galaxy clusters. The widely accepted dark matter theory, meanwhile, can apply to both. But according to new research by astrophysicists, observational data shows that our universe is full of more dead stars than we

Virtual particles, depending on who you ask, are either a yet-unsolved quirk of the mathematics that we use to calculate physics, or a type of real particle that’s constantly popping into existence before quickly disappearing. In a recent paper, physicists claim that they’ve done an experiment that proves that virtual particles are, indeed, real things. Let’s take a look.