The Week in Space and Physics
The Week in Space and Physics
On the first galaxies, ice volcanoes on Pluto, Jupiter's rings and quantum-proof codes
The James Webb certainly opened in style. Its first official image showed us the deepest ever view of the universe: revealing objects billions of light years distant and of unimaginable age. Then, to further show off its impressive abilities, it turned to closer targets; capturing star clusters and galaxies in unprecedented clarity.
These first pictures were intended to impress the public, to congratulate engineers and scientists and to justify, in part, the cost of the telescope. Yet they also offer something more: for astronomers these images are the first glimpse of a rarely seen era. They represent, as such, an early chance to explore an ancient cosmos.
Among the thousands of galaxies seen in the Webb’s first image were a handful that formed extraordinarily early. Astronomers quickly picked out one that formed less than half a billion years after the Big Bang. More careful examination has found some older – apparently forming when the universe was just one or two hundred million years old.
These galaxies look different to the Milky Way. They are very pure – composed almost entirely of hydrogen, the lightest element. Modern galaxies, by contrast, contain many heavier elements such as helium, lithium, oxygen and carbon. Those are the elements that allow planets and moons to form, permit life to evolve and civilization to take root. Yet they also took time to emerge: their atoms were forged in the hearts of burning stars and spectacular supernova.
Those early galaxies are instead made of primordial hydrogen, created in the first few moments of the universe and scattered across the cosmos. When the first galaxies formed – likely clustering around clumps and filaments of dark matter – they should have appeared as dense clouds of this hydrogen. As they collapsed, under the force of gravity, stars would have ignited, and the galaxies we are now beginning to see should have lit up like beacons in the sky.
This process takes time, and astronomers thought that the first galaxies would take several hundred million years to emerge. Yet the early data from the James Webb seems to suggest otherwise: researchers are finding galaxies forming much earlier than should be possible. Astronomers, it seems, may need to rethink the early universe.
Still, caution is advised. Many universities are keen to claim that their astronomers have found the “first” galaxy; the oldest one ever seen by humanity. As they rush to do this, they may overlook inconvenient details, or spruce up evidence that isn’t quite as tantalising as it may look.
The James Webb will surely revolutionise our understanding of the earliest galaxies. But that - properly done - takes time and care. Extraordinary claims, after all, require extraordinary evidence. And the James Webb - however spectacular its images - has not yet provided that.
Ice Volcanoes on Pluto
Before New Horizons flew past Pluto, in 2015, we had only the vaguest sense of the distant world. Astronomers knew it was small and cold, and accompanied by a relatively large moon. But more details were elusive, obscured by the vast distance between it and Earth. Indeed, even in the best images we had, it appeared as little more than a blurry blob.
New Horizons then, passing Pluto at a distance of just eight thousand miles, revealed a largely unknown place. It was, as researchers had expected, frighteningly cold – just a few tens of degrees above absolute zero. But it also proved surprisingly complex, with a rugged surface and evidence of volcanic activity.
These volcanoes, however, are like none seen on Earth. Pluto’s volcanoes seem, as highlighted by a recent paper, to be based around liquid water. On a world as cold as Pluto, this water is normally frozen solid, forming a hard rock-like surface. Yet due to some residual internal heat, Pluto may also have a reservoir of liquid water buried deep beneath its surface.
From time to time, images of the surface suggest, this water erupts upwards; bursting out in enormous “cryovolcanic” eruptions. When it does, it acts rather like lava on Earth, flowing, cooling and eventually hardening to form mountains of rock - or ice - on the surface. Analysis of New Horizon’s images suggests many such volcanoes have formed, and each must have erupted several times.
Yet how this happens is unclear. Pluto should, according to most models, be frozen solid. Heat from radioactivity – which drives volcanism on Earth and many other worlds – should not be enough to create the landscapes seen. Scientists believe that something big smashed into Pluto long ago, throwing out debris that eventually coalesced into Charon, its moon. This collision should have heated Pluto – but by now, billions of years later, that heat must surely have faded.
Something unexpected, then, seems to be heating the interior of Pluto. Researchers are short of ideas – and, unfortunately, are likely to remain so for some time to come. New Horizons gave astronomers a burst of data about Pluto. But no follow-up missions are planned. Pluto, distant and cold, will probably remain unvisited for another half century or more. Its remaining mysteries are likely to endure for decades longer.
The Rings of Jupiter
Do all giant planets come with rings? Though Saturn’s ring system is by far the most dramatic and well-known example, all the other gas giants in the Solar System have rings of their own. Does this rule hold true for all planets, even those around other suns? And why are some rings – like those of Saturn – more dramatic than others?
In an effort to answer these questions, a pair of researchers at the University of California modelled the evolution of Jupiter’s rings over millions of years. Rings, they found, tend to be unstable and short-lived – either coalescing into small moons or being torn apart by larger passing moons. Without a regular source of new material – probably from passing comets and asteroids – the rings would vanish altogether within a few million years.
That, then, neatly explains why Jupiter has small and thin rings. But what about Saturn, home to enormous rings? The answer probably lies in the differences between the two planet’s moons. Jupiter has four big moons, some of which come close to the planet. Saturn, by contrast, has just one big moon, Titan, and it lies far from the planet. That means Saturn’s rings are less affected by the planet’s moons, and can grow larger before they are disturbed by Titan’s presence.
All this points to the crucial role played by moons in allowing rings to grow. Though most – perhaps all – gas giants will host rings, formed from the debris of shattered moons, comets and asteroids – few will see them grow as large or as beautiful as Saturn’s.
Quantum-Proofing the Future
The era of quantum computing, though decades from reality, is beginning to terrify and excite the world’s spies. The crux of their emotions lies in their secret codes; and the ability of quantum computers to break the most advanced encryption methods used today. That promises excitement – the possibility to easily read hidden messages – and fear, as no secret will be safe.
Though quantum computers are unlikely to be able to do this for years to come, agencies are already collecting vast amounts of encrypted data. When quantum computers do become readily available, then, they are likely to be put to work cracking that collected information open; thus revealing vast amounts of data that might be better off hidden away.
Yet not all codes are easily hacked by quantum computers. NIST, the US National Institute of Standards and Technology, has started looking for techniques that are quantum proof. These, once found, could already be applied today. That would provide security that today’s messages will be keep secret even in the age of quantum computing. Four approaches have been selected - yet one, already, has been broken by researchers.