The Universe is thought to consist of three types of substance: normal matter, ‘dark matter’ and ‘dark energy’.
Normal matter consists of the atoms that make up stars, planets, human beings and every other visible object in the Universe.
Normal matter consists of the atoms that make up stars, planets, human beings and every other visible object in the Universe.As humbling as it sounds, normal matter almost certainly accounts for the smallest proportion of the Universe, somewhere between 1% and 10%.
Clusters of galaxies emit lots of X-rays because they contain a large quantity of high-temperature gas. By measuring the quantity of X-rays from a cluster, astronomers can work out both the temperature of the cluster gas and also the mass of the cluster.
Theoretically, in a Universe where the density of matter is high, clusters of galaxies would continue to grow and so, on average, should contain more mass now than in the past.
Most astronomers believe that we live in a low-density Universe in which a mysterious substance known as ‘dark energy’ accounts for 70% of its content, and therefore, pervades everything.
In this scenario, clusters of galaxies should stop growing early in the history of the Universe and look virtually indistinguishable from those of today.
Astronomers using ESA’s XMM-Newton have shown that clusters of galaxies in the distant Universe are not like those of today. They seem to give out more X-rays than expected.
These clusters of galaxies have changed their appearance with time, and calculations also show that in the past there were fewer galaxy clusters.
This indicates that the Universe must be a high-density environment, contradicting current ideas. This conclusion is highly controversial, because to account for these results you have to have a lot of matter in the Universe and that leaves little room for dark energy.
XMM-Newton has given astronomers a new insight into the Universe and a new mystery to puzzle over. These results are being confirmed by other X-ray observations and, if these return the same answer, we might have to rethink our understanding of the Universe.
The universe is filled with billions of galaxies and trillions of stars, along with nearly uncountable numbers of planets, moons, asteroids, comets and clouds of dust and gas – all swirling in the vastness of space.
But if we zoom in, what are the building blocks of these celestial bodies, and where did they come from?
Hydrogen is the most common element found in the universe, followed by helium; together, they make up nearly all ordinary matter. But this accounts for only a tiny slice of the universe — about 5%. All the rest is made of stuff that can't be seen and can only be detected indirectly. [From Big Bang to Present: Snapshots of Our Universe Through Time]
Every bit of matter that makes up all the known elements in the periodic table — and every object in the universe, from black holes to massive stars to specks of space dust — was created during the Big Bang, said Neta Bahcall, a professor of astronomy in the Department of Astrophysical Sciences at Princeton University in New Jersey.
"We don't even know the laws of physics that would have existed in such a hot, dense environment," Bahcall told Live Science.
About 100 seconds after the Big Bang, the temperature dropped to a still-seething 1 billion degrees Kelvin. By roughly 380,000 years later, the universe had cooled enough for protons and neutrons to come together and form lithium, helium and the hydrogen isotope deuterium, while free electrons were trapped to form neutral atoms.
Because there were so many protons zipping around in the early universe, hydrogen — the lightest element, with just one proton and one neutron — became the most abundant element, making up nearly 95% percent of the universe's atoms. Close to 5% of the universe's atoms are helium, according to NASA. Then, about 200 million years after the Big Bang, the first stars formed and produced the rest of the elements, which make up a fraction of the remaining 1% of all ordinary matter in the universe.
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The Universe is thought to consist of three types of substance: normal matter, ‘dark matter’ and ‘dark energy’.
Normal matter consists of the atoms that make up stars, planets, human beings and every other visible object in the Universe.
Normal matter consists of the atoms that make up stars, planets, human beings and every other visible object in the Universe.As humbling as it sounds, normal matter almost certainly accounts for the smallest proportion of the Universe, somewhere between 1% and 10%.
Clusters of galaxies emit lots of X-rays because they contain a large quantity of high-temperature gas. By measuring the quantity of X-rays from a cluster, astronomers can work out both the temperature of the cluster gas and also the mass of the cluster.
Theoretically, in a Universe where the density of matter is high, clusters of galaxies would continue to grow and so, on average, should contain more mass now than in the past.
Most astronomers believe that we live in a low-density Universe in which a mysterious substance known as ‘dark energy’ accounts for 70% of its content, and therefore, pervades everything.
In this scenario, clusters of galaxies should stop growing early in the history of the Universe and look virtually indistinguishable from those of today.
Astronomers using ESA’s XMM-Newton have shown that clusters of galaxies in the distant Universe are not like those of today. They seem to give out more X-rays than expected.
These clusters of galaxies have changed their appearance with time, and calculations also show that in the past there were fewer galaxy clusters.
This indicates that the Universe must be a high-density environment, contradicting current ideas. This conclusion is highly controversial, because to account for these results you have to have a lot of matter in the Universe and that leaves little room for dark energy.
XMM-Newton has given astronomers a new insight into the Universe and a new mystery to puzzle over. These results are being confirmed by other X-ray observations and, if these return the same answer, we might have to rethink our understanding of the Universe.
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The universe is filled with billions of galaxies and trillions of stars, along with nearly uncountable numbers of planets, moons, asteroids, comets and clouds of dust and gas – all swirling in the vastness of space.
But if we zoom in, what are the building blocks of these celestial bodies, and where did they come from?
Hydrogen is the most common element found in the universe, followed by helium; together, they make up nearly all ordinary matter. But this accounts for only a tiny slice of the universe — about 5%. All the rest is made of stuff that can't be seen and can only be detected indirectly. [From Big Bang to Present: Snapshots of Our Universe Through Time]
Every bit of matter that makes up all the known elements in the periodic table — and every object in the universe, from black holes to massive stars to specks of space dust — was created during the Big Bang, said Neta Bahcall, a professor of astronomy in the Department of Astrophysical Sciences at Princeton University in New Jersey.
"We don't even know the laws of physics that would have existed in such a hot, dense environment," Bahcall told Live Science.
About 100 seconds after the Big Bang, the temperature dropped to a still-seething 1 billion degrees Kelvin. By roughly 380,000 years later, the universe had cooled enough for protons and neutrons to come together and form lithium, helium and the hydrogen isotope deuterium, while free electrons were trapped to form neutral atoms.
Because there were so many protons zipping around in the early universe, hydrogen — the lightest element, with just one proton and one neutron — became the most abundant element, making up nearly 95% percent of the universe's atoms. Close to 5% of the universe's atoms are helium, according to NASA. Then, about 200 million years after the Big Bang, the first stars formed and produced the rest of the elements, which make up a fraction of the remaining 1% of all ordinary matter in the universe.
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