HEAVENLY BULLETIN
VAST NOTHINGNESS PUSHES MILKY WAY, TIME’S ARROW GOES BACKWARDS, PLUS THE PUZZLE OF PLANET NINE...
COSMIC DEAD ZONE
A new 3-D map of more than 8,000 galaxies indicates that the Milky Way is being pushed by a vast patch of nothingness half a billion light years from Earth, on the far side of the constellation of Lacerta, the Lizard. This cosmic dead zone may account for as much as half the force that propels our home galaxy through the heavens at 2,000,000 km per hour (1,243,0000 mph). It has long been evident that the Milky Way and its neighbouring galaxy, Andromeda, are being pulled by the gravitational attraction of the most massive structure in the observable universe – the Shapley attractor, a dense ‘supercluster’ of galaxies 750 million light years away. Now, it seems, we are not only being pulled, but pushed. Guardian, 31 Jan 2017.
THE JANUS POINT
There’s nothing in the laws of physics that insists time must move forward. In trying to solve the puzzle of why time seems to move in only one direction, many physicists have settled on entropy, the level of molecular disorder in a system, which continually increases (Newton’s Second Law of Thermodynamics). However, two separate groups of prominent physicists have been working on models that examine the initial conditions that might have created the arrow of time, and both seem to show time moving in two different directions. When the (hypothetical) Big Bang created our universe, these physicists believe it also created an inverse mirror universe where time moves in the opposite direction. (We won’t go into the mathematical nittygritty here.) The physicists call the moment before expansion the “Janus point,” after the twoheaded Roman god. “Time is not something that pre-exists,” said Julian Barbour from the University of Oxford. “The direction and flow of time we have to deduce from what’s happening in the universe. When we look at it that way, it’s natural to say that time begins at that central point and flows away in opposite directions.”
Flavio Mercati from the Perimeter Institute for Theoretical Physics commented: “We’re on one side of the Janus point. On one side you get your arrow of time and can never experience the other one. It’s in your past.” He believes we can never have direct experience of the ‘mirror universe’. The theory is based on classical physics and is far from definitive; once questions of quantum physics are introduced, all bets are off. “Instead of having two streams emanating from a river,” said Prof Barbour, “it could be more like a fountain where you have lots of pairs of springs. Or just a whole host of springs flowing out of a fountain in different directions.”
Lord Rees, the Astronomer Royal, adds another complication: “Many people suspect that our Big Bang was not the only one, but there’s a whole archipelago of Big Bangs,” he told the Hay Literary Festival in Wales last May. He added that other universes may exist unconstrained by the laws of Newtonian physics, with different atoms and gravitational fields. The highly controversial theory that there were multiple Big Bangs as part of a wider ‘multiverse’ was first proposed by Prof Andrei Linde, now at Stanford University. qz.com, cnet.com, 18 Jan; D.Telegraph, 1 June 2016.
PLANET NINE
Over the past two decades, astronomers have detected more than 2,000 planets orbiting stars other than our Sun. A year ago, researchers floated the possibility of an undiscovered large planet at the far edge of the Solar System. Today, astronomers are none the wiser about what is being called Planet Nine, or whether it even exists. (‘Planet Nine’ of our Solar System used to be Pluto, but this heavenly body was downgraded from planetary status in 2006.) Most are sceptical, but the mathematical models used to predict the new planet continue to suggest that there is something out there five to 15 times the mass of the Earth. Efforts to spot it continue, but this is a huge challenge given that it supposedly orbits 20 times further from the Sun than does the gas giant Neptune. The latter orbits the Sun every 165 years, but it takes ‘Planet Nine’ about 17,000 years. This makes a direct observation very difficult,
even using the world’s most powerful telescopes.
It comes down to the ability of mathematics to make astronomical predictions – which led, for instance to the discovery of Neptune. William Herschel spotted the latter’s closer twin, Uranus, in 1781, but two decades later it was clear there was a wobble in its orbit, implying there was something else out there. John Couch Adams and Urbain Jean Joseph Le Verrier used maths to pinpoint its location, and Johann Gottfried Galle used their data to observe Neptune in 1846.
Calculations by Konstantin Batygin and Mike Brown of the California Institute of Technology predicted ‘Planet Nine’ after noticing the unusual orbits of a cluster of bodies in the Kuiper Belt, far beyond Neptune. The points of closest approach of these objects to the Sun, known as their perihelia, almost coincide. Moreover, these perihelia all lie near the ecliptic – the plane of Earth’s orbit and also, approximately, that of the other planets – while the objects’ orbits are all angled at 30 degrees below the ecliptic. Something is shepherding them (and it’s not Nibiru, which, according to the late Zecharia Sitchin, is an enormous planet on an eccentric 360,000-year orbit, home to the Anunnaki who created Homo sapiens and the ancient Sumerian culture).
Not all astronomers agree that ‘Planet Nine’ is the solution to the puzzle; maybe a massive body previously ejected from the Solar System is to blame. As we say at Fortean Towers: “For every expert there is an equal and opposite expert”. Ironically, it was the aforementioned Dr Brown as much as anyone who was responsible for Pluto’s downgrading, for he discovered Eris, an object almost as big as Pluto, in 2005. He uses the handle ‘Pluto-killer’ on Twitter. Guardian, D.Telegraph, 21 Jan; Economist, 23 Jan; D.Mail, 21+25 Jan 2016; Irish Times, 12 Jan 2017.