An asteroid discovered late last year is continuing to stir public interest as its odds of striking planet Earth less than eight years from now continue to increase.

Two weeks ago, when Ars first wrote about the asteroid, designated 2024 YR4, NASA’s Center for Near Earth Object Studies estimated a 1.9 percent chance of an impact with Earth in 2032. NASA’s most recent estimate has the likelihood of a strike increasing to 3.2 percent. Now that’s not particularly high, but it’s also not zero.

Naturally the prospect of a large ball of rock tens of meters across striking the planet is a little worrisome. This is large enough to cause localized devastation near its impact site, likely on the order of the Tunguska event of 1908, which leveled some 500 square miles (1,295 square kilometers) of forest in remote Siberia.

To understand why the odds from NASA are changing and whether we should be concerned about 2024 YR4, Ars connected with Robin George Andrews, author of the recently published book How to Kill an Asteroid. Good timing with the publication date, eh?

Ars: Why are the impact odds increasing?

Robin George Andrews: The asteroid’s orbit is not known to a great deal of precision right now, as we only have a limited number of telescopic observations of it. However, even as the rock zips farther away from Earth, certain telescopes are still managing to spy it and extend our knowledge of the asteroid’s orbital arc around the sun. The odds have fluctuated in both directions over the last few weeks, but overall, they have risen; that’s because the amount of uncertainty astronomers have as to its true orbit has shrunk, but Earth has yet to completely fall out of that zone of uncertainty. As a proportion of the remaining uncertainty, Earth is taking up more space, so for now, its odds are rising.

Think of it like a beam of light coming out of the front of that asteroid. That beam of light shrinks as we get to know its orbit better, but if Earth is yet to fall out of that beam, it takes up proportionally more space. So, for a while, the asteroid’s impact odds rise. It’s very likely that, with sufficient observations, Earth will fall out of that shrinking beam of light eventually, and the impact odds will suddenly fall to zero. The alternative, of course, is that they’ll rise close to 100 percent.

What are we learning about the asteroid’s destructive potential?

The damage it could cause would be localized to a roughly city-sized area, so if it hits the middle of the ocean or a vast desert, nothing would happen. But it could trash a city, or completely destroy much of one, with a direct hit.

The key factor here (if you had to pick one) is the asteroid’s mass. Each time the asteroid gets twice as long (presuming it’s roughly spherical), it brings with it 8 times more kinetic energy. So if the asteroid is on the smaller end of the estimated size range—40 meters—then it will be as if a small nuclear bomb exploded in the sky. At that size, unless it’s very iron-rich, it wouldn’t survive its atmospheric plunge, so it would explode in mid-air. There would be modest-to-severe structural damage right below the blast, and minor to moderate structural damage over tens of miles. A 90-meter asteroid would, whether it makes it to the ground or not, be more than 10 times more energetic; a large nuclear weapon blast, then. A large city would be severely damaged, and the area below the blast would be annihilated.

Microsoft Claims Quantum-Computing Breakthrough—but Some Physicists Are Skeptical

By Davide Castelvecchi & Nature magazine

Microsoft has announced that it has created the first ‘topological qubits’ — a way of storing quantum information that the firm hopes will underpin a new generation of quantum computers. Machines based on topology are expected to be easier to build at scale than competing technologies, because they should better protect the information from noise. But some researchers are sceptical of the company’s claims.

The announcement came in a 19 February press release containing few technical details — but Microsoft says it has disclosed some of its data to selected specialists in a meeting at its research centre in Santa Barbara, California. “Would I bet my life that they’re seeing what they think they’re seeing? No, but it looks pretty good,” says Steven Simon, a theoretical physicist at the University of Oxford, UK, who was briefed on the results.

At the same time, the company published intermediate results — but not the proof of the existence of topological qubits — on 19 February in Nature.

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Superconducting wire

Topological states are collective states of the electrons in a material that are resistant to noise, much like how two links in a chain can be shifted or rotated around each other while remaining connected.

The Nature paper describes experiments on a superconducting ‘nanowire’ device made of indium arsenide. The ultimate goal is to host two topological states called Majorana quasiparticles, one at each end of the device. Because electrons in a superconductor are paired, an extra, unpaired electron will be introduced, forming an excited state. This electron exists in a ‘delocalized’ state, which is shared between the two Majorana quasiparticles.

The paper reports measurements suggesting that the nanowire does indeed harbour an extra electron. These tests “do not, by themselves” guarantee that the nanowire hosts two Majorana quasiparticles, the authors warn.

According to the press release, the team has carried out follow-up experiments in which they paired two nanowires and put them in a superposition of two states — one with the extra electron in the first nanowire, and the other with the electron in the second nanowire. “We’ve built a qubit and shown that you can not only measure parity in two parallel wires, but a measurement that bridges the two wires,” says Microsoft researcher Chetan Nayak.

“There’s no slam dunk to know immediately from the experiment” that the qubits are made of topological states, says Simon. (A claim of having created Majorana states, made by a Microsoft-funded team based in Delft, the Netherlands, was retracted in 2021.) The ultimate proof will come if the devices perform as expected once they are scaled up, he adds.

Early announcement

Some researchers are critical of the company’s choice to publicly announce the creation of a qubit without releasing detailed evidence. “If you have some new results not connected to this paper, why don’t you wait until you have enough material for a separate publication?" says Daniel Loss, a physicist at the University of Basel, Switzerland. “Without seeing the extra data from the qubit operation, there is not much one can comment,” says Georgios Katsaros, a physicist at the Institute of Science and Technology Austria in Klosterneuburg.

“We are committed to open publication of our research results in a timely manner while also protecting the company’s IP [intellectual property],” says Nayak.

Microsoft has also shared a roadmap for scaling up its topological machines and demonstrating that they can perform quantum calculations². Vincent Mourik, a physicist at the Helmholtz Research Centre in Jülich, Germany, whose concerns helped to lead to the earlier retraction, is sceptical of the whole concept. “At a fundamental level, the approach of building a quantum computer based on topological Majorana qubits as it is pursed by Microsoft is not going to work.”

“As we perform more types of measurements, it will become harder to explain our results with non-topological models,” says Nayak. “There may not be one single moment when everyone will be convinced. But non-topological explanations will require more and more fine-tuning.”

This article is reproduced with permission and was first published on February 19, 2025.