Monday, June 18, 2018
NASA's Chandra Observatory explains the science behind black holes
Ripples in spacetime detected by physicists could one day reveal the presence of wormholes that could transport people into another universe.
Gravitational waves, long theorised and first detected in 2016, have already shed light on what some experts say are colliding black holes.
Now a new study claims that colliding wormholes may instead have been responsible for readings picked up on by various teams of scientists in recent years.
Experts have proposed a method of differentiating between the two - monitoring for the presence of echoes they say are characteristic of wormholes.
Although current technology isn't sensitive enough to pick up on these variations in readings of gravitational waves, that may change in the near future.
Researchers from KU Leuven University and the University of Madrid created a model that predicts how gravitational waves caused by the collision of two rotating wormholes could be detected.
So far, gravitational wave signals that have been observed are completely extinguished after a few moments.
This is believed to be a consequence of the presence of the event horizon on the black holes they emanate from.
But if this event horizon did not exist, as is believed to be the case in wormholes, these oscillations would not disappear altogether.
Instead, there would be echoes in the signal that would continue for some time, which may have gone unnoticed until now.
In a written statement, researcher Pablo Bueno said: 'Wormholes do not have an event horizon, but act as a space-time shortcut that can be traversed, a kind of very long throat that takes us to another universe.
'And the fact that they also have rotation changes the gravitational waves they produce.'
Scientists have long theorised the existence of black holes, backed up by a multitude of experiments, theoretical models and indirect observations.
That includes recent detections of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (Ligo) and its partner Virgo observatory.
They are believed to originate from the collision of two of these dark cosmic monsters.
There is a problem with black holes, however. Their edges, called event horizons, mean matter, radiation or anything that enters them can no longer escape.
This is in conflict with the laws of quantum mechanics, which state that information will always be preserved, not destroyed.
One of the theoretical ways to deal with this conflict is to explore the possibility that the alleged black holes we observe in nature are no such thing.
Instead, they may be some kind of exotic compact object (ECOs), a category which includes wormholes and other strange phenomena known as fuzzballs, gravastars and boson stars.
As wormholes do not have an event horizon, this would leave its mark on the gravitational waves recorded by the Ligo experiment and its partner Virgo observatory.
'The final part of the gravitational signal detected by these two detectors - what is known as ringdown - corresponds to the last stage of the collision of two black holes, added Pablo Cano from KU Leuven University in Belgium.
'This has the property of completely extinguishing after a short period of time due to the presence of the event horizon.
'However, if there were no horizon, those oscillations would not disappear completely.
'Instead, after a certain time, they would produce a series of "echoes", similar to what happens with the sound in a well.'
Astronomers believe wormholes could some day allow interstellar travel.
The problem with using wormholes to travel in space or time is that they are inherently unstable.
When a particle enters a wormhole, it also creates fluctuations that cause the structure to collapse in on it.
However, some studies have claimed that travelling through these theoretical shortcuts might be possible - in spite of the extreme forces at play.
They could be used to traverse distances from a few metres, across lightyears or even to entirely new universes, some say.
The full findings of the study were published in the journal Physical Review D.
Posted by ASC at 10:42 PM