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Dark Energy. We Know. It’s Complicated!

posted: 05/10/16
by: Cody Barr
Dark Energy
Dark Energy
NASA/JPL

It should come as no surprise that the trope "seeing is believing" is not always the case. In the realm of space exploration, it's quite the opposite. The most puzzling facet of the Universe lies in the darkness. Dark matter and dark energy continue to exist without direct evidence, but their presence is very much real. We know it's complicated, so to help explain the currently unexplainable, we turned to Dr. Ian O'Neill from DNews, who holds a Ph.D in Solar Physics and an M.Phys in Astrophysics.

What is the most common misconception people have when it comes to things we can't see in space like dark matter and dark energy?

The biggest misconception is that they don't exist because we only have indirect evidence. People read these articles and expect a quick fix. They think we need to tune up our instruments, that we're looking in the wrong place, that we are missing something. It's not a conspiracy. You always have people that say it's just something that scientists say to get research funding. That's not the case.

There are arguments that we need to look at our understanding of gravity or space time, perhaps. As the years go on and we've studied gravitational waves, Einstein was pretty much spot on when it comes to general relativity. We think it's a problem with matter.


Above: Our friends from Test Tube ponder dark spaces as well!

How do you convince the general public that research into this sector of astrophysics and space exploration is necessary?

People are used to this "Golden Age" of scientific discovery where we have answers for everything. They want us to tie all our theories together into little bows and explain the Universe and move on with our lives. Of course, it doesn't work like that.

I would argue that the endeavor itself is worthy because of all the other things we learn along the way of any scientific discovery. The spinoff technologies from the endeavors will enrich our lives. And it's just nice to know about our place in the Universe. It's like a bottomless ocean. Wouldn't you like to know what's below you on the ocean floor instead of floating around blindly taking it for granted? What's beyond what we can see and understand is what makes humanity tick.

What is the main piece of evidence scientists have found to confirm the presence of dark matter?

We have a good idea that perhaps the majority of our matter is made up of invisible particles that exert a gravitational force collectedly, but are very small and don't interact via electromagnetic force, which means we can't see them directly. You can't look into the sky and see the radiation it exerts because it doesn't emit any. Its presence is known by gravitational force only.

We look at galaxies. We see that galaxies spin like a wheel, not like whirlpool. Whirlpools spin the fastest motion in the center and the slowest on the outside. Galaxies don't act like that. That's what they would do if all of the matter in the Universe was visible. But because most is invisible (85%), the visible material of the galaxy moves virtually as a whole because it's embedded in a massive halo of dark matter that is around it. So we're only seeing the middle of this halo, which is actually visible. It extends very far away. The oval motion of the dark matter is like whirlpool, but we only see the visible hub of visible matter.

Are there any other pieces of evidence?

You can look at galactic clusters, the motion of gasses and stars and motion of light going through galactic clusters. We know it's out there.

What sort of experiments and observations are being done to advance our understanding of dark matter?

Scientists are trying to produce dark matter ourselves by using The Large Hadron Collider and are simultaneously trying to observe it in the galaxies. The most exciting is the LHC (The Large Hadron Collider). It is constantly crashing particles at nearly the speed of light, something that hadn't happened since the Big Bang. These scientists are creating minute quantities of primordial matter and are finding strange bumps in the energy of the particles that come out of such collisions. There's the possibility of finding a new particle found that we have never seen before. It could very well be a dark matter particle because it has a gravitational force.

Meanwhile, the ISS is trying to detect energies from the center of galaxies. WIMPs in certain conditions, may collide and annihilate. When they collide, they erupt with a sudden burst of energy. The hope is to detect that energy, to detect the annihilation of dark matter particles. Everything is inconclusive right now, but there are papers seemingly every six months saying the finger prints of dark matter has been found.

People make associations between dark matter, dark energy and black holes because the color black is dark. Are they actually connected?

They certainly can be connected. Black holes are extremely dense locations and carry a lot of gravitational weight. Are there more than we know of? Possibly. We're realizing that all galaxies have super massive black holes in their cores. We can see our black hole because of its interaction with local matter in our galaxies. We can't actually see our black hole because it's black but we can detect it from radio waves and the heat it emits.

There's a theory that there are many many black holes out there that don't interact with any matter because they're not near any matter. It could be a small black hole at our cosmic doorstep that doesn't produce any radiation. They could be a very large component of dark matter. The connection is very real and logical. Hopefully we can detect more black hole collisions through gravitational waves.

What about dark energy? How do we know it exists?

The main evidence for dark energy comes really comes from Hubble's original mission at the turn of the century. It saw that all the galaxies are essentially moving away from each other at an accelerated rate, which didn't make sense at the time. Now, it's almost like there's this anti-gravity component to the Universe (dark matter) and matter energy is actually held up in this dark energy. It's really hard to explain.

What sort of steps would a young enthusiast need to take to enter this field and be at the forefront of this research?

I went into astrophysics because of science fiction. I had to first understand all the disciplines of physics and then mathematics. You have to have a grasp on mathematics. For me, I loved the mystery of the Universe and wanted to understand it. It comes from excitement and enthusiasm. When you realize how big the Earth is and how tiny we are in relation to the rest of the Universe you feel a little bit scared, like a claustrophobia, but the desire to understand it is undeniable.

For those interested in exploring the concept of dark energy and learning Einstein's and the Hubble's role in proving its existence, you must watch tonight's episode of Space's Deepest Secrets: Dark Energy starting at 10P. Get started with the clip below!

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