The Week in Space and Physics #5
At first glance magnetism and electricity seem to have little in common. Magnets - from the flutter of a compass needle to the glow of the aurora - seem more tangible, more real than the invisible flow of electrons through a wire. And yet, the two are deeply intertwined; two faces of the same deep and fundamental force of electromagnetism.
This realisation, made in the early nineteenth century, gave humanity mastery over nature. Manipulating magnetism allowed us to produce electricity, to send radio waves across the planet, to drive motors and machinery. Without it, in short, our modern world would barely exist.
Yet there is one crucial difference between magnetism and electricity. All known magnetic particles have two exactly opposite poles – one north and one south. Electric particles, however, can have only one “pole”, carrying an overall negative charge – like electrons - or a positive one, like protons. That means electricity can flow, forming an energy carrying current, while magnetism cannot.
The laws of physics, though, contain no reason why this should be. Indeed, many fundamental laws hint that magnetism should behave more like electricity, with magnetically charged particles free to move. That would imply the existence of a magnetic monopole: a hypothetical particle that carries only one pole: north or south, instead of north and south.
Finding or creating a magnetic monopole would have deep implications for physics. It would – thanks to a theory by the physicist Paul Dirac – explain why electric charge seems to be discrete, rather than continuous. It could resolve an ugly asymmetry in the laws of electromagnetism and – if we could harness magnetic circuits – might allow us to manipulate electricity and magnetism in entirely new ways.
No wonder, then, that physicists have been hunting for one for a long time. But bar a single possible sign in the 1980s, no evidence of their existence has ever been seen. That means – since they are theoretically easy to detect – that they must be rare in the universe, if they exist naturally at all.
Some physicists have instead turned their attention to trying to create one artificially. Particle colliders are, in theory anyway, capable of doing this; though whether we have one powerful enough is not clear. To find out, researchers recently undertook a study of the intense magnetic fields formed inside the Large Hadron Collider, in Switzerland.
They were hoping to spot magnetic particles popping into existence in that field – just as other particles do when enough energy is concentrated in one place. But even looking at the strongest magnetic field ever created – perhaps stronger than any other in the galaxy – they still did not find a single monopole.
Still, absence of proof is not proof of absence. Without an underlying reason why monopoles cannot exist, physicists are likely to keep searching. Plans are already afoot to create more powerful fields in the Large Hadron Collider in the near future. Maybe, just maybe, scientists will then spot the mythical monopole popping briefly into existence.
Musk, Starship and Solar Storms
Elon Musk rarely seems to have relaxing weeks, but the last one may have been stressful even for him. First came news of a disastrous deployment of fifty new Starlink satellites, resulting in the destruction of at least forty of them. Then, standing in front of a four hundred foot high rocket, Musk spoke of the challenges facing Starship – and of a likely long delay before its first orbital launch.
The ill-fated satellites were, like all Starlink satellites, released at a low altitude: just 130 miles above the Earth. Normally onboard propulsion systems would then power on, pushing the satellites up to higher orbits. This time, however, a solar storm had just swept by, heating and expanding the atmosphere.
This effect is well known, often resulting in increased drag on low flying satellites and thus pulling them back down to Earth. The Starlink satellites fell victim to this: falling faster than they could climb and - eventually - burning up in the upper atmosphere.
That may not be too much of a blow to Starlink. With more than two thousand Starlink satellites already in orbit, forty more or less makes little difference. The effect of solar storms, however, may be more of a risk in future. The Sun will become more active over the next few years, heating the upper atmosphere and dragging low satellites down.
Starship, meanwhile, seems trapped in a regulatory quagmire. Musk’s preferred launch site, in the south of Texas, needs governmental approval before it can be used for orbital launches. How long that might take is unclear - in a best case it could be approved within weeks, but it could easily drag on for years. Musk could move launches to Florida, where SpaceX is already cleared for launch. But that too would take several months to prepare.
Still, Musk did get a bit of good news last week. A group of amateur astronomers had earlier predicted an old SpaceX rocket was on a collision course with the Moon. Now, however, that group thinks the rocket in question is actually Chinese – and not from SpaceX at all. That may save Musk another round of sensational headlines.
A Breakthrough in Nuclear Fusion
The era of clean and unlimited energy from nuclear fusion seems, ever so slightly, to be drawing closer. Such statements, of course, should be taken cautiously. Fusion has a long history of expected breakthroughs and – as an old joke goes – has been twenty years away from reality for decades.
Still, the progress this time seems to be real and encouraging. Researchers at a lab in England succeeded in running a fusion reaction for a record five seconds, producing around sixty megajoules of energy. That may not sound impressive – certainly five seconds is not very long, and sixty megajoules not very much – but the result was at the upper limit of the facility’s capabilities.
In a larger reactor - say at ITER, a reactor being built in France - the same approach could yield more impressive results. Researchers are hoping to reach a breakeven point, where the fusion reaction produces more energy than is used to start it. That moment - long sought, but never achieved - would be a true breakthrough in fusion research.
That is probably a decade or more away. ITER is not expected to open until at least 2025, even if all remaining engineering work goes as plan. The first experiments, then, may begin by 2030, with a true demonstration of fusion power possible sometime in the 2030s. Full scale fusion – no matter what anyone says – is still where it always was, two decades in the future.
Another Planet for Proxima Centauri
Astronomers this week reported finding a third planet around Proxima Centauri, the closest star to the Sun. Though the data is still early and unconfirmed, researchers estimate that the planet is smaller than the Earth, perhaps nearer the size of Mars, and orbits far closer to its star.
That means it is a hot and arid world; one with no prospect for supporting life. That would have been unlikely anyway – Proxima Centauri is a “flare star”, prone to violent outbursts of energy. Planets close to it – such as this new one – are bathed in radiation and victim to frequent solar storms.
Still, the discovery of such a small planet is good news for the team behind it. They are using a new instrument – ESPRESSO – mounted on a telescope in Chile to hunt for small planets. Normally such worlds are hard to detect, as they leave only faint traces of their presence. ESPRESSO, however, is sensitive enough to pick out these signs. It will likely discover many more Earthlike - or Marslike - planets in the years ahead.