Astronomers have discovered what they say is the largest known structure in the universe: an incredibly big hole.
The “supervoid”, as it is known, is a spherical blob 1.8 billion light years across that is distinguished by its unusual emptiness.
István Szapudi, who led the work at the University of Hawaii at Manoa, described the object as possibly “the largest individual structure ever identified by humanity”.
Szapudi’s team was intentionally searching for the void because they believed that it could explain previous observations showing that part of the sky is unusually cool.
The so-called Cold Spot was discovered 10 years ago and has proved a sticking point for the best current models for how the universe evolved following the Big Bang.Cosmological theory allows for a bit of patchiness in the background temperature, due to warmer and cooler spots of various sizes emerging in the infant universe, but areas as large and cold as the Cold Spot are unexpected.
Prof Carlos Frenk, a cosmologist at the University of Durham, said: “The Cold Spot raised a lot of eyebrows. The real question was what was causing it and whether it was a challenge to orthodoxy.”
The latest study suggests that the Cold Spot can be partly explained by a gigantic region of emptiness at its centre, which drains energy from light travelling through it.
The supervoid is not an actual vacuum, as its name suggests, but has about 20% less stuff in it than our part of the universe – or any typical region. “Supervoids are not entirely empty, they’re under-dense,” said András Kovács, a co-author at the Eötvös Loránd University in Budapest.
The structure may sound unremarkable – hardly a standalone object even – but scientists say it is unprecedented given how evenly distributed the universe normally is at this spatial scale. “This is the greatest supervoid ever discovered,” Kovács said. “In combination of size and emptiness, our supervoid is still a very rare event. We can only expect a few supervoids this big in the observable universe.”
Previously, astronomers observing in the direction of the Cold Spot had established that there was no distant void in that part of the sky, but until now the nearer sky had not been surveyed.
The latest study used the Hawaii’s Pan-STARRS1 (PS1) telescope located on Haleakala, Maui, and Nasa’s Wide Field Survey Explorer (WISE) satellite to count the number of galaxies in a patch of sky around 3 billion light years away – relatively close in the cosmic scheme of things.
The survey, described in Monthly Notices of the Royal Astronomical Society, confirmed that there was a roughly spherical region that was far less densely populated by galaxies than the surrounding sky and that it was centred on the Cold Spot.
However, rather than solving the puzzle the latest discovery has only served to deepen the mystery. “It just pushed the explanation one layer deeper,” said Dr Roberto Trotta, a cosmologist at Imperial College London. “Now we have to figure out how does the void itself form. It’s still a rare event.”
Even more perplexing, according to Frenk, is the fact that the supervoid can only account for about 10% of the Cold Spot’s temperature dip.
“The void itself I’m not so unhappy about. It’s like the Everest of voids – there has to be one that’s bigger than the rest,” he said. “But it doesn’t explain the whole Cold Spot, which we’re still in the dark about.”
This partial explanation could point to the existence of “exotic physics”: new weird effects that scientists don’t yet know about.
The existence of an empty patch helps explain the Cold Spot because assuming the universe is expanding at an accelerating rate, photons of light would be expected to lose energy (cool) as they cross a void.
This is because the photons convert kinetic energy to gravitational potential as they travel to the heart of the void and get further from denser surrounding patches of universe – think of it as climbing a hill. In a stationary universe, the situation would be symmetrical and so the photons would regain the lost energy on the way out of the void (down the hill). In an accelerated expansion of the universe, however, everything is effectively becoming less dense as space is stretched out, so voids become relatively shallower over time. This means by the time the light descends the virtual hill, the hill has become flatter and the light cannot pick up all the energy it lost on the way in. This means the light exits with a longer wavelength, corresponding to a cooler temperature.
The observation that the Cold Spot and supervoid coincide would fit with the idea that the universe is indeed expanding at an accelerating rate, which scientists put down to forces linked to dark energy. “This is independent evidence, in case anyone doubts it, for the existence of dark energy,” said Frenk.
This article was amended on the 21st of April to make it clear that light travels at a constant speed, but changes wavelength.
WHAT IS A ‘SUPERVOID’?
- A supervoid is not empty, but rather a region of space that has less matter than other parts of the universe.
- For this reason it can ‘sap’ the energy of light that is passing through it.
- To explain how that works, imagine the void to be a hill. As light enters the void and travels towards its middle, it can be said to be climbing the hill, using up energy.
- Once it passes the centre, it would begin ‘descending’ the hill and regain the energy it expended to get there.
- But as the universe is expanding, by the time the light gets to the centre, its route out has become ‘shallower’ – or less dense.
- This means it cannot regain as much energy as it lost initially and leaves the void with less energy, therefore a longer wavelength, which corresponds to a colder temperature.
- The different is marginal – typically about 70 nano-Kelvins – but it is enough to stand out when the entire cosmic microwave background radiation (CMB) of the universe is measured.
Source: Daily Mail and NASA
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And I will shew wonders in heaven above, and signs in the earth beneath; blood, and fire, and vapour of smoke (Acts 2:19 KJV).
”..keep that which is avoiding profane and vain babblings, and oppositions of science falsely so called: Which some professing have erred concerning the faith…” (1 Timothy 6:20-21 KJV).
For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made,even his eternal power and Godhead; so that they are without excuse – Romans 1:20 (KJV).
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Of old hast thou laid the foundation of the earth: and the heavens are the work of thy hands. They shall perish, but thou shalt endure: yea, all of them shall wax old like a garment; as a vesture shalt thou change them, and they shall be changed:-Psalm 102:25-26 (KJV).
For this they willingly are ignorant of, that by the word of God the heavens were of old, and the earth standing out of the water and in the water:- 2 Peter 3:5 (KJV).
Who is the image of the invisible God, the firstborn of every creature: For by him were all things created, that are in heaven, and that are in earth, visible and invisible, whether they be thrones, or dominions, or principalities, or powers: all things were created by him, and for him: And he is before all things, and by him all things consist – Colossians 1:15-17 (KJV).
Seek him that maketh the seven stars and Orion, and turneth the shadow of death into the morning, and maketh the day dark with night: that calleth for the waters of the sea, and poureth them out upon the face of the earth: The LORD is his name:- Amos 5:8 (KJV).
Lift up your eyes on high, and behold who hath created these things, that bringeth out their host by number: he calleth them all by names by the greatness of his might, for that he is strong in power; not one faileth – Isaiah 40:26 (KJV).
Which commandeth the sun, and it riseth not; and sealeth up the stars. Which alone spreadeth out the heavens, and treadeth upon the waves of the sea. Which maketh Arcturus, Orion, and Pleiades, and the chambers of the south. Which doeth great things past finding out; yea, and wonders without number – Job 9:9-10 (KJV).
…”Can you bind the chains of the Pleiades, Or loose the cords of Orion?” Can you lead forth a constellation in its season, And guide the Bear with her satellites? “Do you know the ordinances of the heavens, Or fix their rule over the earth?…- Job 38:31-33