Sabine Hossenfelder: Backreaction

tag:blogger.com,1999:blog-229733572026-07-02T11:00:00.212-04:00Sabine Hossenfelder: BackreactionCan we understand the universe? Read my blog to find out what we know, may one day know, and will probably never know.Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger2895125tag:blogger.com,1999:blog-22973357.post-90529499719753322532026-07-02T11:00:00.000-04:002026-07-02T11:00:00.203-04:00The Biggest Argument for Dark Matter Just Died

Physicists have been arguing about dark matter for almost a century, and now, after all this time, their most favourite evidence for dark matter – the Bullet Cluster – disappeared. This isn’t just an interesting development from a scientific perspective, it is also a good illustration for what is going wrong in this research area. I have a brief summary.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-81856563580766426432026-06-30T11:00:00.000-04:002026-06-30T11:00:00.111-04:00Strange Things Are Happening in Quantum Computing

Quantum computing is supposed to be one of the most exciting new technologies that humanity is working on, with companies promising it can be used in chemistry, material science, logistics, and finance. Over the years, those use cases have been slowly eroded, but investment in quantum tech has only increased. Why? Let’s take a look.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-6522579778749902022026-06-27T11:00:00.000-04:002026-06-27T11:00:00.158-04:00Consciousness Comes From Quantum Processes, Physicist Claims

Since the early days of quantum physics, some scientists have believed that there’s a link between quantum mechanics and consciousness. While most researchers don’t think this idea holds water, a few have published papers about how phosphate molecules in the brain could link consciousness to quantum physics. Let’s take a look.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-85136071383656608112026-06-24T11:00:00.000-04:002026-06-24T11:00:00.111-04:00The Future of AI No One Wants to Talk About

In today's video I speculate about the future of AI

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-74964273280877159142026-06-23T11:00:00.000-04:002026-06-23T11:00:00.110-04:00Controversy Erupts over Expansion of Universe: Nobel Prize Awarded in Error?

In 2011, three physicists won the Nobel Prize for showing that the expansion of the universe speeds up, which is usually attributed to aa mysterious type of energy called “dark energy”. But last year, though, a different group published research showing that universal expansion isn’t actually getting faster. Since then, the two groups have engaged in a whole bunch of back-and-forth refuting each

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-71619434933554294822026-06-20T11:00:00.000-04:002026-06-20T11:00:00.161-04:00Nuclear fusion is in trouble

In the past months, several nuclear fusion startup have pivoted to selling other technologies and some have silently shifted their timelines.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-66621424883781376992026-06-17T11:00:00.000-04:002026-06-17T11:00:00.109-04:00Maths is Cooked: AI's Latest Breakthrough -- And What's Next

As AI continues to improve its reasoning abilities, mathematicians are increasingly worried about the computer algorithms replacing them. In late May, those fears got even worse when OpenAI revealed that one of its general-purpose reasoning models had written a proof solving a math problem that’s sat unsolved for more than 80 years. But should they actually be worried? Let’s take a look.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-40170276513582600322026-06-15T11:00:00.000-04:002026-06-15T11:00:00.115-04:00Did Physics Just Lose a Brilliant Idea?

One of the most popular ideas in physics right now is something named “ER = EPR.” This theory has it that entangled particles are actually linked by tiny, tiny wormholes. Recently, a group of physicists tested the idea – let’s take a look at their findings.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-47952209756174003802026-06-13T11:00:00.000-04:002026-06-13T11:00:00.113-04:00 We're Not Ready for Self-Building AI, But it's Happening

Artificial Intelligence is beginning to improve itself. In today's video I have a summary of recent events. Are we ready for the intelligence explosion? I think not.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-66258868974047353592026-06-11T11:00:00.000-04:002026-06-11T11:00:00.112-04:00Physicists Are Rethinking Dark Matter… In The Wrong Way.

Physicists believe that 80% of the matter in the universe is made of ‘dark matter’ that we can’t see. But despite decades of work, they haven’t been able to confirm that this matter really exists. In the past years, physicists have been rethinking the dark matter idea… but not in the way you might expect. Let’s take a look.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-22761900357455149162026-06-09T11:00:00.000-04:002026-06-09T11:00:00.119-04:00Microsoft Announces Breakthrough With Quantum Chip

Last year, Microsoft announced its Majorana quantum computing chip, which supposedly used topological qubits to make calculations. The problem was that the paper published alongside the announcement didn’t show any evidence for those claims. Now they’ve announced a new quantum chip. Is it any better this time?. Let’s take a look.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-77581856759714036732026-06-05T11:00:00.000-04:002026-06-05T11:00:00.110-04:00 America is coming for Europe's most important machine

The Dutch company ASML is the only company that produces a special type of machine used to produce microchips, which are a key component of many modern technologies. Now, companies across the globe are looking to break ASML’s monopoly using a wide variety of new processes. Let’s take a look at this microchip manufacturing melee.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-87816598797763404052026-06-03T11:00:00.000-04:002026-06-03T11:00:00.112-04:00This Giant Ring In Space Poses A Massive Problem For Cosmology

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.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-56770244670786532912026-05-31T11:00:00.000-04:002026-05-31T11:00:00.114-04:00Super El Niño: How Accurate Are These Predictions?

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.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-79024415681167061382026-05-26T11:00:00.000-04:002026-05-26T11:00:00.115-04:00These Physicists Claim They Can Send Messages To The Past

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

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-2193166413969053442026-05-23T11:00:00.000-04:002026-05-23T11:00:00.121-04:00I Looked at the New Cold Fusion Breakthroughs. It's Complicated.

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.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-54989477576354473312026-05-21T11:00:00.000-04:002026-05-21T11:00:00.114-04:00The unbearable blandness of the 2020s

In today's rant I complain that I now sound like every other YouTuber.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-12746656586120430032026-05-19T11:00:00.000-04:002026-05-19T11:00:00.123-04:00Biologists Say They Cracked One of Life’s Biggest Mysteries

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.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-12197482005237994652026-05-17T11:00:00.000-04:002026-05-17T11:00:00.115-04:00This Startup Promises Energy From Nothing—Here's What's Wrong

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.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-14622087943928202412026-05-13T11:00:00.001-04:002026-05-13T11:00:00.156-04:00These new nuclear reactors solve the safety problem

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.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-77527093171917595732026-05-12T11:00:00.001-04:002026-05-12T11:00:00.114-04:00AI Will Hit a Wall in 2026, if nothing changes.

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.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-53803091658052045662026-05-10T11:00:00.002-04:002026-05-10T11:00:00.120-04:00Einstein's Theory Has a Problem -- This Idea Solves It

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.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-40990313729070641362026-05-07T11:00:00.001-04:002026-05-07T11:00:00.116-04:00Quantum physics is an unnecessary complication, researchers say

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.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-46651121525082943072026-05-05T11:00:00.001-04:002026-05-05T11:00:00.119-04:00New Theory Explains How Time Began

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

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0tag:blogger.com,1999:blog-22973357.post-56006102367454937722026-05-02T11:00:00.001-04:002026-05-02T11:00:00.136-04:00Bacteria could survive trip on asteroid, scientists find

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.

Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.com0