The Week in Space and Physics
The Week in Space and Physics
On the future of particle physics, sudden galactic death, the moon rocket and an odd pattern in the Earth's crust
The days when a lone genius could revolutionise physics are long gone. Modern physics is a team sport; one with little patience for solo stars like Einstein or Newton. In their place are teams of dozens, even hundreds, of researchers, operating vastly expensive machinery. This transition rings especially true in particle physics: a field that sometimes sees a thousand names on a single research paper.
Yet particle physics is also a field badly in need of a revolution. At first that might seem slightly odd. Its current fundamental theory – known as the Standard Model – has been wildly successful at explaining the known subatomic world. It predicted the Higgs Boson; accounted for all known particles, from the W-boson to the Tau Neutrino; and neatly explained three of the four known forces of nature.
But the Standard Model does not explain other mysteries. It gives no clue to the nature of dark matter, or to the mysterious force behind dark energy. It cannot explain the nature of gravity, nor resolve the question of why our universe has a surplus of matter over antimatter. These lingering problems, most physicists think, imply the existence of a deeper theory that neatly resolves such loose ends.
Where will that revolution come from, if not from a modern Einstein? For a long time physicists looked to ever more powerful colliders, the Large Hadron Collider (LHC), in Switzerland, chief among them. Yet, despite exploring energies far higher than ever before, these colliders have spectacularly failed to find the evidence needed for a new theory of nature.
That leaves particle physics in a tight spot. Some call for even more powerful - and expensive - colliders, arguing that new physics lies just beyond the range of the LHC. Yet a growing chorus is arguing for a new approach; one that shifts the focus to new experiments and new particles.
At the heart of the problem may be the nature of modern physics itself. In a field dominated by huge consortiums of researchers, it can be hard be radical ideas to be heard. Groupthink seems to prevail – with unproven and often untestable ideas like supersymmetry and string theory swinging in and out of fashion. Particle physicists often seem stuck, repeating the same tired ideas over and over in the hope of uncovering something new.
Whether this will change anytime soon is unclear. A recent conference discussing the future of particle physics, Snowmass, ended without any clear path forward being identified. Hints of flaws in the standard model – found at CERN and Fermilab – remain unproven and unclear. New theories, reaching beyond supersymmetry and string theory, are only slowly emerging, and have little experimental data to support them.
Fixing this will take more than new experiments and colliders. Physicists need to rethink the way physics is done, and examine why the last few decades have seen so few breakthroughs. The age of the lone genius may indeed be over, but its replacement is still far from ready.
The Galaxies Are Dying. Why?
Years ago, when I was on the verge of postgraduate study, a professor told me something shocking. The universe, she said, is dying. The rate of star birth is falling drastically; and as it does the cosmos is slowly losing its splendour. New stars are being born at an ever slower rate, and more and more galaxies are “quenching” – that is, suddenly putting an end to the creation of new stars.
This tragedy is playing out on a vast scale, all across the known universe and over a timescale of billions of years. To illustrate this story, my professor drew a simple graph. On the left, representing the distant past, its line soared to a majestic peak. Yet as the curve moved to the right it fell away, gradually decreasing to nothing. This line, she told me, represented the number of new stars being born in the universe over time.
The question, which would lie at the heart of her proposed research topic, was to explain why this was happening. The contours of the problem are fairly clear: to form stars you need gas, and over time galaxies gradually use up the gas they were born with. Yet on closer examination things are more complex: rather than a gradual decline, most galaxies seem to suddenly stop making new stars at some point.
That implies that most galaxies encounter an event that rapidly strips them of usable gas. Many theories have been proposed as to what this can be: perhaps sudden flurries of erupting supernova violently throw much of the gas out of a galaxy, or a black hole expels what is left in an energetic jet of debris. Now, however, astronomers have spotted a clear sign of a galaxy losing its gas.
Using the Hubble Space Telescope, they examined a galaxy lying some seven billion light years away. Evidence shows it has recently collided with another galaxy, and this event, it seems, has stripped its gas away. That gas now lies in a long tail stretching away from the galaxy and, shorn of this fuel, the galaxy has ceased creating new stars.
It is not yet clear if this observation can explain why so many galaxies have ceased star formation. Many of those closest to the Milky Way appear in this dead state; can they all have been the victim of such collisions? Fortunately our own galaxy has, for now at least, been spared such a fate.
Yet things may not stay this way for long: the Milky Way is on a collision course with Andromeda. When they met the collision is likely to shred both galaxies and, sadly, expel the vital gas that feds baby stars.
A September Launch for the SLS?
The end of September promises to be a busy period for NASA. Two launches were already planned. One, carrying a new crew to the International Space Station, is scheduled for October 3rd. Another, the launch of asteroid probe DART, is planned for September 26th. Now, NASA also hopes to squeeze in another launch attempt for Artemis I, the first flight of the new SLS rocket.
After efforts to launch the SLS failed earlier this month, NASA must make some repairs and changes before trying again. Replacing damaged seals – from which dangerous hydrogen was leaking – is the most crucial task. NASA currently plans to have the new seals ready for a test on the 17th, following which the rocket should be cleared for lift-off.
A second problem concerns a set of batteries inside the rocket. These power the “flight termination system”, a module that controllers will use to safely destroy the rocket in case it veers off course after lift-off. Normally the batteries are supposed to be replaced after three weeks, but doing so is a complicated task, and would likely require the rocket to be taken back into the hanger.
This three week deadline, however, is somewhat artificial, and NASA believes the rocket will be safe even if the batteries stay a few weeks longer. That theory will need to be officially certified before launch can take place.
If the tests and certification can be completed in time, NASA has identified two dates for the attempt. The first is on the morning of September 23rd, the other is on September 27. Should these efforts fail, NASA will have to wait until the end of October for the next opportunity to fly.
The Continents and the Galaxy
Researchers have found an odd pattern in the Earth’s crust. Every two hundred million years, they say, the growth of the crust seems to accelerate: boosting the rate at which the continents are formed. This seems to correlate well with another pattern: the movement of the Earth in and out of the galaxy’s spiral arms.
The team behind the study suggest that when the solar system moves into one of the galactic arms, the cloud of ice and dust lying far beyond Pluto is disturbed. This sends a rain of comets inwards, bringing rock and water to the Earth and other planets.
A sudden burst of impacts could also melt part of the crust – an event that should allow material to well up from the Earth’s core to its surface. That, in turn, aids the formation of the thick crust that makes up the continents; as opposed to the thinner crust lying under the oceans. The arms of the galaxy, then, may have sculpted the continents on Earth.