Our universe started with an incredibly rapid phase of expansion, growing exponentially before that expansion eventually slowed down. This idea is called “inflation,” but physicists are still unsure what caused the rapid expansion and why it stopped. In a new paper, researchers say they’ve come up with an elegant new explanation for that inflation. Let’s take a look.

According to a growing body of physics research, the dark energy in our universe is weakening over time. This indicates that our current standard cosmological model does not fit reality. Recently, a team of researchers came up with a theory which they claim does fit the new observations – they say that dark energy is caused by black holes. Let’s take a look.

According to Einstein’s theories, the universe started with a Big Bang singularity and is slowly expanding until it disperses into nothingness. But physicists have also come up with theories claiming that the Big Bang was non-singular and can repeat, restarting the cycle over again. These are called “cyclic models,” and they’ve re-emerged into the spotlight now that there’s mounting evidence that dark energy is weakening over time. However, a physicist from UC Berkeley recently published a paper which he claims “categorically rules out” cyclic models. Let’s take a look.

According to a growing body of data, dark energy is not constant. Instead, physicists claim, it’s slowly getting weaker. This has understandably shaken our understanding of the universe – this week, physicists show that the new data is compatible with string theory, and that the universe will eventually collapse. Let’s take a look.

Gravitational memory” is the idea that gravity’s ability to duplicate information from other forces should somehow store that information in certain masses. A group of physicists has now published a series of papers claiming that this idea might solve the black hole information loss problem and explain dark matter. Really? Let’s take a look.

We’ve already discussed the crisis in cosmology multiple times on this channel. Recently, that crisis was only made worse thanks to new data from the South Pole Telescope. Their numbers again show that dark energy – which drives the expansion of the universe – weakens over time, which could mean that the universe is destined to collapse one day. I find this very surprising because honestly I thought I would have to tell you that this crisis disappeared, but not so. Let’s take a look.

Soon after Stephen Hawking died in 2018, his collaborator Thomas Hertog published his posthumous “final theory.” Basically, the theory builds on the idea of eternal inflation, which says that new universes are constantly being created from an even-larger sea of quantum fluctuations. Hawking’s theory sought to explain that these births happened more gradually and less disruptively, bringing the theory closer to what we observe in our universe. How groundbreaking is this theory really? Let’s take a look.

A new study has found that the universe might be spinning. What does that even mean? Let’s have a look.



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Cosmology, the branch of physics that deals with the universe, is facing a bit of a crisis right now. Four crises, actually. Let’s take a look at the biggest problems with our current understanding of the universe and how we got here to begin with.



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Physicists have come up with a new idea for how our universe began, and it could also explain dark matter. They say that if our universe has small extra dimensions, then these can temporarily store energy, causing a “cosmological stasis” in which the universe expands but nothing else happens. Then the stasis ends and dark matter remains. Sounds wild. What are we to make of this?

Most physicists believe that our universe began with a Big Bang. But how did the laws of nature – for example, the strength of gravity, the speed of light, and the strength of electromagnetic interaction – come to be the way they are? A group of physicists have just put forth an interesting hypothesis on that question in a new paper. Let’s take a look.

Physicists think that our universe started out as just a lot of quantum fluctuations. That means, if you’re able to calculate wave-function of those quantum fluctuations, you can learn how the universe ended up the way it is now. In a pre-print, a group of physicists around Nima Arkani-Hamed say they’ve worked out a new powerful method to calculate the wave function of the early universe, and they’re calling it the “cosmohedra.” Let’s take a look.



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In my second book, Existential Physics", I wrote about the possibility that the universe might be able to think. You might think I’m joking, or gone off the deep end, or both – but hear me out.

According to our current understanding of astrophysics, the universe is not only expanding, but also growing at an ever-increasing rate. The most-accepted model for this expansion attributes the accelerated expansion to dark energy – but what if it’s wrong? A group of astrophysicists have offered up a different explanation, which they call the “timescape” model. They claim that it fits the data better than dark energy. Let’s take a look.



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The Big Bang is the first moment our universe existed according to calculations within Einstein’s theory of general relativity. But then what is the “Dark Big Bang” that some physicists are talking about? Does this really solve any problems, or is it just another theory that we’ll never be able to test? Let’s find out.



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According to the multiverse theory, we are likely to find ourselves in a universe particularly suited to the emergence of life. According to a new paper, though, that’s not the case given how it’s expanded over time. But does that mean the multiverse theory has also been invalidated? Let’s take a look.

I recently saw a new paper that claims our observations could be better explained if the universe was surrounded by a shell. According to the author, that could do away with dark energy and alleviate the Hubble tension. I had a look at the paper.

Physicists from the University of Queensland in Australia have found evidence that time ran slower in the past. In this video I explain how time-dilation is related to redshift, what that means for light from distant galaxies, and what happens to an observer who falls into a black hole.

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If you google the “worst prediction ever”, you will get hundreds of results that tell you it was the prediction of the cosmological constant that was infamously 120 orders of magnitude wrong. But there has never been any such prediction. Just where does this story come from and what is really the worst prediction ever?

I got quite a few questions about a paper that supposedly revolutionizes our understanding of the universe by throwing out energy conservation. The questions came in two varieties. Can you do that, isn’t energy always conserved? And isn’t energy conservation violated anyway? I thought it would be interesting to clear this up because I think the idea isn’t remotely as crazy as it sounds. Let’s have a look.