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.
This simulation shows the instant in which two black holes merge. The collision of two rotating wormholes would trigger a similar deformation of space-time, experts say
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.'
WHAT ARE WORMHOLES AND COULD THEY TRANSPORT US ACROSS THE UNIVERSE?
Space-time can be warped and distorted, although It takes an enormous amount of matter or energy to create such distortions.
In the case of the wormhole, a shortcut is made by warping the fabric of space-time.
Imagine folding a piece of paper with two pencil marks drawn on it to represent two points in space-time.
Space-time can be warped and distorted, although It takes an enormous amount of matter or energy to create such distortions. In the case of the wormhole (artist's impression), a shortcut is made by warping the fabric of space-time
The line between them shows the distance from one point to the other in normal space-time.
If the paper is now bent and folded over almost double - the equivalent to warping space-time - then poking the pencil through the paper provides a much shorter way of linking the two points, in the same way a wormhole would create a shortcut.
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
.Wormhole connecting centre of Galaxy with distant point
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.
WHAT ARE BLACK HOLES?
Black holes are so dense and their gravitational pull is so strong that no form of radiation can escape them - not even light.
They act as intense sources of gravity which hoover up dust and gas around them.
Their intense gravitational pull is thought to be what stars in galaxies orbit around.
How they are formed is still poorly understood.
Supermassive black holes are incredibly dense areas in the centre of galaxies with masses that can be billions of times that of the sun. They cause dips in space-time (artist's impression) and even light cannot escape their gravitational pull
Astronomers believe they may form when a large cloud of gas up to 100,000 times bigger than the sun, collapses into a black hole.
Many of these black hole seeds then merge to form much larger supermassive black holes, which are found at the centre of every known massive galaxy.
Alternatively, a supermassive black hole seed could come from a giant star, about 100 times the sun's mass, that ultimately forms into a black hole after it runs out of fuel and collapses.
When these giant stars die, they also go 'supernova', a huge explosion that expels the matter from the outer layers of the star into deep space.
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.
WHAT ARE GRAVITATIONAL WAVES?
Scientists view the the universe as being made up of a 'fabric of space-time'.
This corresponds to Einstein's General Theory of Relativity, published in 1916.
Objects in the universe bend this fabric, and more massive objects bend it more.
Gravitational waves are considered ripples in this fabric.
Gravitational waves are considered ripples in the fabric of spacetime. They can be produced, for instance, when black holes orbit each other or by the merging of galaxies
They can be produced, for instance, when black holes orbit each other or by the merging of galaxies.
Gravitational waves are also thought to have been produced during the Big Bang.
Scientists first detected the shudders in space-time in 2016 and the discovery was hailed the 'biggest scientific breakthrough of the century'.
Experts say gravitational waves open a 'new door' for observing the universe and gaining knowledge about enigmatic objects like black holes and neutron stars.
Gravitational waves DO exist proving Einstein's theory
'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.
HOW DOES THE LIGO DETECTOR WORK?
Ligo is made up of two observatories that detect gravitational waves by splitting a laser beam and sending it down several mile (kilometre) long tunnels before merging the light waves together again.
A passing gravitational wave changes the shape of space by a tiny amount, and the Ligo was built with the ability to measure a change in distance just one-ten-thousandth the width of a proton.
However, this sensitivity means any amount of noise, even people running at the site, or raindrops, can be detected.
The Ligo detectors are interferometers that shine a laser through a vacuum down two arms in the shape of an L that are each 2.5 miles (four kilometres) in length.
The light from the laser bounces back and forth between mirrors on each end of the L, and scientists measure the length of both arms using the light.
If there's a disturbance in space-time, such as a gravitational wave, the time the light takes to travel the distance will be slightly different in each arm making one arm look longer than the other.
Ligo (pictured) is made up of two observatories that detect gravitational waves by splitting a laser beam and sending it down several mile (kilometre) long tunnels before merging the light waves together again
Ligo scientists measure the interference in the two beams of light when they come back to meet, which reveals information on the space-time disturbance.
The ensure the results are accurate, Ligo uses two observatories, 1,870 miles (3,000 kilometres) apart, which operate synchronously, each double-checking the other's observations.
The noise at each detector should be completely uncorrelated, meaning a noise like a storm nearby one detector doesn't show up as noise in the other.
Some of the sources of 'noise' the team say they contend with include: 'a constant 'hiss' from photons arriving like raindrops at our light detectors; rumbles from seismic noise like earthquakes and the oceans pounding on the Earth's crust; strong winds shaking the buildings enough to affect our detectors.'
However, if a gravitational wave is found, it should create a similar signal in both instruments nearly simultaneously.
Supermassive black hole captured 'eating' a star while producing a jet with 125 BILLION times more energy than the sun in world first
- Experts discovered the event in a pair of colliding galaxies called Arp 299
- It was first observed in 2005 when experts found a bright burst of infrared
- Now they have captured a fast-moving jet of material being ejected from it
- Only a small number of such stellar deaths have ever been detected, experts say
An enormous black hole has been captured 'eating' a star 150 million light years away.
Experts have taken images of a fast-moving jet of material being ejected from the cosmic monster, which is 20 million times more massive than the sun.
They claim the superfast jet of particles packed about 125 billion times the amount of energy the sun releases per year.
Only a small number of such stellar deaths, called tidal disruption events (TDEs), have ever been detected.
However, scientists believe that they may have been a more common occurrence in the early days of the universe.
Studying them may help researchers better understand the environment in which galaxies developed billions of years ago.
Scroll down for video
Experts say the superfast jet of particles packed about 125 billion times the amount of energy the sun releases per year. Pictured is an artist's impression
An enormous black hole has been captured 'eating' a star 150 million light years away. Experts have taken images of a fast-moving jet of material being ejected from the cosmic monster (pictured), which is 20 million times more massive than the sun
An international team of scientists, including from the National Radio Astronomy Observatory at the University of Virginia, tracked the event with radio and infrared telescopes in a pair of colliding galaxies called Arp 299.
At the core of one of the galaxies, a supermassive black hole shredded a star more than twice the Sun's mass, setting off a chain of events that revealed important details of the violent encounter.
Experts say that material pulled from the doomed star forms a rotating disk around the black hole, emitting intense X-rays and visible light, as well as launching jets of material outward from the poles of the disk at nearly the speed of light.
'Never before have we been able to directly observe the formation and evolution of a jet from one of these events,' said Miguel Perez-Torres, of the Astrophysical Institute of Andalusia in Granada, Spain, who was involved in the research.
WHAT ARE BLACK HOLES?
Black holes are so dense and their gravitational pull is so strong that no form of radiation can escape them - not even light.
They act as intense sources of gravity which hoover up dust and gas around them.
Their intense gravitational pull is thought to be what stars in galaxies orbit around.
How they are formed is still poorly understood.
Supermassive black holes are incredibly dense areas in the centre of galaxies with masses that can be billions of times that of the sun. They cause dips in space-time (artist's impression) and even light cannot escape their gravitational pull
Astronomers believe they may form when a large cloud of gas up to 100,000 times bigger than the sun, collapses into a black hole.
Many of these black hole seeds then merge to form much larger supermassive black holes, which are found at the centre of every known massive galaxy.
Alternatively, a supermassive black hole seed could come from a giant star, about 100 times the sun's mass, that ultimately forms into a black hole after it runs out of fuel and collapses.
When these giant stars die, they also go 'supernova', a huge explosion that expels the matter from the outer layers of the star into deep space.
A massive black hole has been caught 'snacking' on gases
The first indication of the presence of the black hole came on January 30, 2005, when astronomers using the William Herschel Telescope in the Canary Islands discovered a bright burst of infrared emission coming from the nucleus of one of the colliding galaxies in Arp 299.
On July 17, 2005, the National Science Foundation's Very Long Baseline Array (VLBA) revealed a new, distinct source of radio emission from the same location.
Continued observations with the VLBA, the European VLBI Network (EVN), and other radio telescopes, carried out over nearly a decade, showed the source of radio emission expanding in one direction, just as expected for a jet.
The measured expansion indicated that the material in the jet moved at an average of one-fourth the speed of light.
Fortunately, the radio waves are not absorbed in the core of the galaxy, but find their way through it to reach the Earth.
These observations used multiple radio-telescope antennas, separated by thousands of miles (km), to gain the resolving power, or ability to see fine detail, required to detect the expansion of an object so distant.
The patient, years-long data collection rewarded the scientists with the evidence of a jet.
An international team of scientists tracked the event in a pair of colliding galaxies called Arp 299, depicted in a Hubble telescope image in the background of this composite picture
Most galaxies have supermassive black holes, containing millions to billions of times the mass of the Sun, at their cores.
In a black hole, the mass is so concentrated that its gravitational pull is so strong that not even light can escape.
When those supermassive black holes are actively drawing in material from their surroundings, that material forms a rotating disk around the black hole, and superfast jets of particles are launched outward.
This is the phenomenon seen in radio galaxies and quasars.
'Much of the time, however, supermassive black holes are not actively devouring anything, so they are in a quiet state,' Dr Perez-Torres added.
'Tidal disruption events can provide us with a unique opportunity to advance our understanding of the formation and evolution of jets in the vicinities of these powerful objects.'
The initial infrared burst was discovered as part of a project that sought to detect supernova explosions in such colliding pairs of galaxies.
Arp 299 has seen numerous stellar explosions, and has been dubbed a 'supernova factory.'
This new object originally was considered to be a supernova explosion.
Only in 2011, six years after discovery, the radio-emitting portion began to show an elongation. Subsequent monitoring showed the expansion growing, confirming that what the scientists are seeing is a jet, not a supernova.
Mattila and Perez-Torres led a team of 36 scientists from 26 institutions around the world in the observations of Arp 299.
They published their full findings in the journal Science.
Experts tracked the event with radio and infrared telescopes, including , the National Science Foundation's Very Long Baseline Array (pictured)
No comments:
Post a Comment