Author: Jonny Lupsha, News Writer
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New images from the Hubble Telescope are inconsistent with dark matter theories, Science Alert reported Friday. For example, there may be much higher concentrations of dark matter throughout the universe than previously thought. What makes dark matter so special?
According to Science Alert, our understanding of dark matter in the universe may soon take one giant leap backwards. “New observations from the Hubble Space Telescope have found much higher concentrations of dark matter than expected in some galaxies, by over an order of magnitude,” the article said. “These concentrations are inconsistent with theoretical models, suggesting that there’s a big gap in our understanding—the simulations could be incorrect, or there could be a property of dark matter we don’t understand.
“Dark matter is one of the biggest thorns in our understanding of the universe—simply put, we don’t know what it is.”
Since dark matter doesn’t absorb, reflect, or emit any kind of electromagnetic radiation, it’s difficult to detect at all. However, it is present in our universe.
What Sets Dark Matter Apart?
“Dark matter and dark energy are different than ordinary matter,” said Dr. Sean Carroll, Senior Research Associate in Physics at the California Institute of Technology. “It’s not just that we’ve missed something—that there are some stars we haven’t seen yet or there is some gas and dust that has spread smoothly throughout the universe, and this is really the dark energy.
“The truth is that all of the particles, all of the ordinary stuff, all the stuff that is made of atoms and molecules is counted in ‘ordinary matter.’ Dark matter and dark energy are something we haven’t detected directly.”
Dr. Carroll said that our belief in dark matter doesn’t come from some kind of mistake in observing the universe. Multiple independent observations have arrived at the conclusion that something otherwise undetectable by modern science is going on in the universe. These observations are made using gravity.
An Extension of the Tangible
If you were to raise your hand and wave it through the air, you could feel the sensation of something reacting to your hand since the air exerts a force against your hand. How do we do something similar to that in outer space?
“We can’t just put our hand into the sky and wave it around, but we can feel the force of gravity,” Dr. Carroll said. “More precisely, we can detect the influence of gravity on other celestial objects. If there is some stuff out there in the universe, some stuff that exists, and there is as much of it or even more of it than there is ordinary matter, that stuff will create a gravitational field, [and] we can detect that gravitational field.
“That’s what provides us the secret to detecting the dark side of the universe.”
To demonstrate this abstract scientific concept, Dr. Carroll said to imagine if the Moon were totally invisible. We could still make approximate measures of the Moon by investigating the oceans’ tides, since the Moon affects them.
“The Moon has a gravitational field; that field pushes around the waters in the oceans and the bays here on Earth and you can therefore detect, just by looking at the waves and at the tides in the oceans, that there must be something exerting a gravitational field,” he said. “You could even figure out where it was and you could weigh it. You could figure out how much gravity it had to be exerting.”
The invisible Moon is an example of how scientists are beginning to understand dark matter. However, owing to recent Hubble images, we may be back to square one in comprehending what it really is.
Dr. Sean Carroll contributed to this article. Dr. Carroll is a Senior Research Associate in Physics at the California Institute of Technology. He earned his undergraduate degree from Villanova University and his PhD in Astrophysics from Harvard in 1993.