This tedious cosmic landscape exists because the universe really was boring once. Shortly after the Big Bang, and for hundreds of thousands of years after that, it was relentlessly dull. All that existed was a thick red-hot haze of particles, stretching for trillions upon trillions of kilometers and filling every point in the universe almost evenly, with minuscule differences in the density of matter between one spot and another.
But as the universe expanded and cooled, gravity amplified those tiny differences. Slowly, over the following millions and billions of years, the places in the universe with slightly more stuff attracted even more stuff. And that’s where we came from—the profusion of things in the universe today eventually arose as more and more material accumulated, making those slightly over-dense regions into radically complicated places packed with enough matter to form stars, galaxies, and us. On the very largest scales, boredom still reigns, as it has since the beginning of time. But down here in the dirt, there’s ample variety.
This story still has some holes. For one thing, it is not clear where the matter came from in the first place. Particle physics demands that anything that creates matter must also create an equal amount of antimatter, carefully conserving the balance between the two. Every kind of matter particle has an antimatter twin that behaves like matter in nearly every way. But when a matter particle comes into contact with its antimatter counterpart, they annihilate each other, disappearing and leaving behind nothing but radiation.
That’s exactly what happened right after the Big Bang. Matter and antimatter annihilated, leaving our universe aglow with radiation—and a small amount of leftover matter, which had slightly exceeded the amount of antimatter at the start. This tiny mismatch made the difference between the universe we have today and an eternity of tedium, and we don’t know why it happened. “Somehow there was this little imbalance and it turned into everything—namely, us. I really care about us,” says Lindley Winslow, an experimental particle physicist at MIT. “We have a lot of questions about the universe and how it evolved. But this is a pretty basic kindergarten sort of question of, okay, why are we here?”
Caught in the act
To answer this question, Winslow and other physicists around the world have constructed several experiments to catch nature in the act of violating the balance between matter and antimatter. They hope to see that violation in the form of neutrinoless double-beta decay, a type of radioactive decay. At the moment, that process is theoretical—it may not happen at all. But if it does, it would provide a possible explanation for the imbalance between matter and antimatter in the early universe.
These robots know when to ask for help
A new training model, dubbed “KnowNo,” aims to address this problem by teaching robots to ask for our help when orders are unclear. At the same time, it ensures they seek clarification only when necessary, minimizing needless back-and-forth. The result is a smart assistant that tries to make sure it understands what you want without bothering you too much.
Andy Zeng, a research scientist at Google DeepMind who helped develop the new technique, says that while robots can be powerful in many specific scenarios, they are often bad at generalized tasks that require common sense.
For example, when asked to bring you a Coke, the robot needs to first understand that it needs to go into the kitchen, look for the refrigerator, and open the fridge door. Conventionally, these smaller substeps had to be manually programmed, because otherwise the robot would not know that people usually keep their drinks in the kitchen.
That’s something large language models (LLMs) could help to fix, because they have a lot of common-sense knowledge baked in, says Zeng.
Now when the robot is asked to bring a Coke, an LLM, which has a generalized understanding of the world, can generate a step-by-step guide for the robot to follow.
The problem with LLMs, though, is that there’s no way to guarantee that their instructions are possible for the robot to execute. Maybe the person doesn’t have a refrigerator in the kitchen, or the fridge door handle is broken. In these situations, robots need to ask humans for help.
KnowNo makes that possible by combining large language models with statistical tools that quantify confidence levels.
When given an ambiguous instruction like “Put the bowl in the microwave,” KnowNo first generates multiple possible next actions using the language model. Then it creates a confidence score predicting the likelihood that each potential choice is the best one.
The Download: inside the first CRISPR treatment, and smarter robots
The news: A new robot training model, dubbed “KnowNo,” aims to teach robots to ask for our help when orders are unclear. At the same time, it ensures they seek clarification only when necessary, minimizing needless back-and-forth. The result is a smart assistant that tries to make sure it understands what you want without bothering you too much.
Why it matters: While robots can be powerful in many specific scenarios, they are often bad at generalized tasks that require common sense. That’s something large language models could help to fix, because they have a lot of common-sense knowledge baked in. Read the full story.
Medical microrobots that travel inside the body are (still) on their way
The human body is a labyrinth of vessels and tubing, full of barriers that are difficult to break through. That poses a serious hurdle for doctors. Illness is often caused by problems that are hard to visualize and difficult to access. But imagine if we could deploy armies of tiny robots into the body to do the job for us. They could break up hard-to-reach clots, deliver drugs to even the most inaccessible tumors, and even help guide embryos toward implantation.
We’ve been hearing about the use of tiny robots in medicine for years, maybe even decades. And they’re still not here. But experts are adamant that medical microbots are finally coming, and that they could be a game changer for a number of serious diseases. Read the full story.
5 things we didn’t put on our 2024 list of 10 Breakthrough Technologies
We haven’t always been right (RIP, Baxter), but we’ve often been early to spot important areas of progress (we put natural-language processing on our very first list in 2001; today this technology underpins large language models and generative AI tools like ChatGPT).
Every year, our reporters and editors nominate technologies that they think deserve a spot, and we spend weeks debating which ones should make the cut. Here are some of the technologies we didn’t pick this time—and why we’ve left them off, for now.
New drugs for Alzheimer’s disease
Alzmeiher’s patients have long lacked treatment options. Several new drugs have now been proved to slow cognitive decline, albeit modestly, by clearing out harmful plaques in the brain. In July, the FDA approved Leqembi by Eisai and Biogen, and Eli Lilly’s donanemab could soon be next. But the drugs come with serious side effects, including brain swelling and bleeding, which can be fatal in some cases. Plus, they’re hard to administer—patients receive doses via an IV and must receive regular MRIs to check for brain swelling. These drawbacks gave us pause.
Sustainable aviation fuel
Alternative jet fuels made from cooking oil, leftover animal fats, or agricultural waste could reduce emissions from flying. They have been in development for years, and scientists are making steady progress, with several recent demonstration flights. But production and use will need to ramp up significantly for these fuels to make a meaningful climate impact. While they do look promising, there wasn’t a key moment or “breakthrough” that merited a spot for sustainable aviation fuels on this year’s list.
One way to counteract global warming could be to release particles into the stratosphere that reflect the sun’s energy and cool the planet. That idea is highly controversial within the scientific community, but a few researchers and companies have begun exploring whether it’s possible by launching a series of small-scale high-flying tests. One such launch prompted Mexico to ban solar geoengineering experiments earlier this year. It’s not really clear where geoengineering will go from here or whether these early efforts will stall out. Amid that uncertainty, we decided to hold off for now.