The ‘Muon g-2’ experiment conducted at the Fermi National Accelerator Laboratory (also known as Fermilab) in the United States has provided strong evidence for the existence of a new fundamental force of nature.
We currently know of four fundamental forces, the strong and weak nuclear forces, the electromagnetic force and the force of gravity. This latest experimental evidence could be a step on the way to adding a fifth force to this list.
The experiment has been studying the behaviour of muons – particles similar to electrons but around 200 times more massive – as they wobble in response to a magnetic field.
A muon’s behaviour in these magnetic fields is determined by a quantity known as its ‘g-factor’, which is a measure of the strength of the particle’s own internal magnetic field. However, the muon’s wobble should also be influenced by the existence of what’s know as ‘quantum foam’. This is a host of virtual particles, predicted by quantum field theory to instantaneously pop in and out of existence in the vacuum of empty space.
The results of the Fermilab experiments show that the size of the effect of this quantum foam on the muon’s wobble is greater than predicted by the ‘Standard Model’ of particle physics – the theory describing the known fundamental forces in the universe (not counting gravity which doesn’t yet fit in with our understanding of quantum mechanics) and classifying all known elementary particles. This could mean that a new fundamental force or particle is affecting the muons’ behaviour.
So far the evidence for a new force is strong – around the ‘4.1-sigma’ level, meaning that there is around a one in a 40,000 chance that the result could be a statistical fluke. However more research will be needed to reach the 5-sigma level – a one in 3.5 million chance of the observation being a coincidence – that is required by the scientific community to claim a new discovery.
If it turns out that a new fundamental force needs to be added to the list, this could revolutionise our understanding of the universe, perhaps providing an explanation for problems with our current cosmological models such as the unknown nature of dark energy and dark matter.
A global network of radio telescopes known as the Event Horizon Telescope (EHT) has produced the first ever image of the silhouette of a black hole.
The image shows hot luminous gas surrounding the black hole’s event horizon – the sphere beyond which light cannot escape the black hole’s gravitational influence.
The team responsible has worked for over a decade to improve upon the technique of Very Long Baseline Interferometry in order to capture the image. The resolution of a telescope is usually dependent upon the size of the dish, or aperture – usually equivalent to the width of the mirror or lens in an optical telescope or the the width of the dish in the case of a radio telescope. The technique of interferometry creates a much larger ‘synthetic aperture’ by linking the images from two or more telescopes together. The further apart the telescopes, the larger the synthetic aperture. The EHT’s synthetic aperture has a resolution equivalent to a dish with a diameter equal to the distance between Spain and the South Pole – where the two furthest apart telescopes in the array are located.
Five petabytes of data were used to construct the image. Because current internet speeds are not sufficient to handle this amount of data, it had to be physically transported to a central location from all eight sites in the EHT array.
The black hole is located at the center of the M87 galaxy – a supergiant elliptical galaxy in the constellation of Virgo. Estimates for the mass of this black hole range from around 3.5 to 6.6 billion times the mass of the Sun.
The supermassive black hole is surrounded by a rotating accretion disk of ionized gas. The disk rotates at a velocity of roughly 1,000 km per second and has a maximum radius of around 0.2 light years, or around 12,000 Astronomical Units (where 1 Astronomical Unit (AU) is the equivalent to the average distance between the Earth and the Sun). The radius of the black hole’s event horizon – or Schwarzschild radius – is around 120 AU.
The black hole’s powerful magnetic field causes it to emit a narrow jet of ionised material from the accretion disk aligned with its axis of rotation. The material in this jet travels at relativistic speeds and reaches a distance of at least 5,000 light years from the black hole.
Water ice deposits have been found in cliff-like structures known as ‘scarps’ at eight different sites on Mars, using the HiRISE camera on NASA’s Mars Reconnaissance Orbiter.
It has previously been shown that there is shallow ground ice under roughly a third of the Martian surface, detected with spectrometers and ground-penetrating radar from orbiting spacecraft. The exposed faces of these scarps provide us with a cross-sectional view though this ice, which is over 100 metres thick in some places. Continue reading →
On 19 October 2017, an astronomer at the Haleakala Observatory, Hawaii, spotted an object passing through our solar system on an unusual hyperbolic trajectory. The strange cigar-like shape of the object lead some to speculate that it could be the product of an extraterrestrial civilization. Continue reading →
On 22 February 2017, astronomers announced that the faint Jupiter-sized ultra-cool red dwarf star TRAPPIST-1, in the constellation of Aquarius, is host to seven Earth-sized planets, all of which are within the stars’ ‘habitable zone’, where it is possible that liquid water could be present.
The exoplanets have not yet been imaged directly but were detectable due to the dimming of the light from TRAPPIST-1, as the planets transited across the face of the star. Continue reading →
The IceCube neutrino telescope in Antarctica, the Fermi gamma ray telescope in low earth orbit and an array of radio telescopes across the Southern Hemisphere, have been used collaboratively to pinpoint a neutrino source in deep space for the first time. Continue reading →
The first ever confirmed detection of gravitational waves has been announced by the Laser Interferometer Gravitational-wave Observatory (LIGO) at a press conference held in Washington DC at 10:30 EST on Thurday, 11 February 2016 .
LIGO’s detection of ripples in the fabric of spacetime has been heralded as one of the scientific breakthroughs of the century and promises to mark the dawn of a new science of gravitational-wave astronomy. Continue reading →