This is one of those stories that, if you’re a science buff whose enthusiasm far outstrips your actual knowledge of the subject matter, makes the hairs on the back of your head stand up and goose pimples appear.
Apparently, one of the great mysteries of the universe is being unravelled as I write this – and in spectacular fashion:
One of the greatest mysteries of the universe is about to be unravelled with the first detailed, three-dimensional map of dark matter – the invisible material that makes up most of the cosmos.
Astronomers announced yesterday that they have achieved the apparently impossible task of creating a picture of something that has defied every attempt to detect it since its existence was first postulated in 1933.
Scientists have known for many years that there is more to the universe than can be seen or detected through their telescopes but it is only now that they have been able to capture the first significant 3D-image of this otherwise invisible material.
Unlike the ordinary matter of the planets, stars and galaxies, which can be seen through telescopes or detected by scientific instruments, nobody has seen dark matter or knows what it is made of, though calculations suggest that it is at least six times bigger than the rest of the visible universe combined.
The significance of this is absolutely startling. And like all other scientific discoveries I’ve tried to understand over the years there is a terrific detective story at the heart of it – a story that reveals the best of who we are as a species as individual scientists, struggling to understand what was previously unknowable, shine a light into the darkest places of the mind to illuminate the fundamental mysteries of the universe.
The search for dark matter began in earnest once scientists realized that all the matter in the “visible” universe – including objects and phenomena not only open to study in the range of visible light but also x-rays, gamma rays, radio waves the infrared and ultraviolet spectrums – made up only a small portion of the mass of the universe. Something else was there – something exotic and mysterious. It’s existence was inferred in a variety of way but most importantly, by a phenomena known as “gravitational lensing.” Basically, this effect is achieved as very, very distant light is “bent” when it passes through a large astronomical body like a galaxy or a cluster of galaxies. The image behind these bodies appears much bigger and a variety of observations can be made that led scientists to the belief that the visible matter in the lensed object couldn’t account for all the “bending” in the light. Something else was at work, something unseen.
Using the Hubble Space Telescope and a bit of creative thinking, scientists have actually been able to “map” an area of space and image dark matter:
A team of 70 astronomers from Europe, America and Japan used the Hubble space telescope to build up a picture of dark matter in a vast region of space where some of the galaxies date back to half the age of the universe – nearly 7 billion years.
They used a phenomenon known as gravitational lensing, first predicted by Albert Einstein, to investigate an area of the sky nine times the size of a full moon. Gravitational lensing occurs when light from distant galaxies is bent by the gravitational influence of any matter that it passes on its journey through space.
The scientists were able to exploit the technique by collecting the distorted light from half a million faraway galaxies to reconstruct some of the missing mass of the universe which is otherwise invisible to conventional telescopes.
“We have, for the first time, mapped the large-scale distribution of dark matter in the universe,” said Richard Massey of the California Institute of Technology in Pasadena, one of the lead scientists in the team. “Dark matter is a mysterious and invisible form of matter, about which we know very little, yet it dominates the mass of the universe.”
And in what surely must be considered a moment of triumph for cosmologists, this study’s observations have confirmed the theoretical – a red letter day in any theoretician’s life:
One of the most important discoveries to emerge from the study is that dark matter appears to form an invisible scaffold or skeleton around which the visible universe has formed.
Although cosmologists have theorised that this would be the case, the findings are dramatic proof that their calculations are correct and that, without dark matter, the known universe that we can see would not be able to exist.
“A filamentary web of dark matter is threaded through the entire universe, and acts as scaffolding within which the ordinary matter – including stars, galaxies and planets – can later be built,” Dr Massey said. “The most surprising aspect of our map is how unsurprising it is. Overall, we seem to understand really well what happens during the formation of structure and the evolution of the universe,” he said.
Now the challenge will be to figure out what dark matter is made of. Already, these observations are being put to good use:
“Now that we have begun to map out where dark matter is, the next challenge is to determine what it is, and specifically its relationship to normal matter,” Dr Massey said. “We have answered the first question about where the dark matter it, but the ultimate goal will be to determine what it is.”
Various experiments on Earth are under way to try to find out what dark matter is made of. One theory is that it is composed of mysterious sub-atomic particles that are difficult to detect because they do not interact with ordinary matter and so cannot be picked up and identified by conventional scientific instruments. Comparing the maps of visible matter and dark matter have already pointed to anomalies that could prove critical to the understanding of what constitutes dark matter.
If the past is any guide, what we find will elicit more goose bumps as discovery by discovery, the universe gives up her secrets to the inquisitive minds of scientists.
I have always found it laughable that there exists a school of thought that mankind’s greatest achievements were actually the result of intervention by aliens from another civilization. The pyramids, the Nazca lines, even Stonehenge, according to this “theory,” were all built by aliens because we humans just aren’t clever enough to have done it ourselves.
Discoveries like this prove that the alien hunters consistently sell our species short. We have in the past and will continue in the future, to use our minds and imaginations to the utmost to solve the riddles of our existence – without the help of anyone else.