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Dark Matter and Dark Energy: What We Currently Know

Updated on March 22, 2012
Dark matter cannot be photographed but can be observed by its gravitational effects on galaxies and galaxy clusters. The blue overlay is used to show dark matter distribution which is then used to understand dark energy.
Dark matter cannot be photographed but can be observed by its gravitational effects on galaxies and galaxy clusters. The blue overlay is used to show dark matter distribution which is then used to understand dark energy. | Source

The expansion of the Universe, contrary to previous beliefs, is accelerating. The Hubble Space Telescope in the late 90s provided observations to reveal this information. The focus then turned to why. Why is the Universe expanding at a faster and faster rate than it was in the beginning? Are our theories incorrect? Or do we simply need to revisit other versions of our current theories? Is there something new in the Universe? In attempts to find an answer, several theories developed but dark matter and dark energy took center stage.

Dark matter is thought to be forming a ring around this galaxy cluster named CL0024+17.
Dark matter is thought to be forming a ring around this galaxy cluster named CL0024+17. | Source

Dark Matter

The idea of dark matter became popular because it offered a possible explanation to how gravity was playing a role in accelerating astral bodies. The concept of dark matter was first introduced by Zwicky in 1934 to explain the movement of galaxy clusters. We know that dark matter exists because observations reveal that approximately 26% of the Universe is made up of matter. However, only about 4% of that matter can readily be seen and is composed of atoms. Observations support that the remaining 22% of matter must be dark matter.

Despite knowing that dark matter exists and that it makes up about 22% of the Universe, we still know next to nothing about what dark matter actually is. Researchers have ruled out the possibilities that dark matter is dark clouds of normal matter, antimatter, or galaxy-sized black holes. What we know of these three possibilities does not apply to dark matter. Current thoughts are that dark matter may actually be normal matter, but is condensed into brown dwarfs, MACHOs (dense chunks of heavy elements), or made up of exotic particles such as axions and WIMPs. Although vast amounts of data have been collected and interpreted, the data is still inconclusive at this point.

Dark Energy

Dark energy makes up the remaining 74% of the universe. This energy exists throughout space and is increasing the rate at which the Universe expands. No one knows why there is so much more dark energy than dark matter as the Universe ages. From what we can tell, there was less of it (or possibly even none at all) in the earlier stages of the Universe's evolution. Some believe this may simply be a matter of coincidence. Dark energy, according to current knowledge, remains a mystery.

One of the concerns regarding dark energy and the accelerated expansion of the Universe is that our current theories my be wrong or in need of adjustment. There is a possibility that Einstein's theory of gravity is incorrect, leaving us to have to start over on explaining how normal matter behaves in galaxies and galaxy clusters. However, none of the new proposals to date have proven anywhere near as accurate as Einstein's theory.

Another idea is that we simply need to revisit an earlier version of Einstein's theory. He suggested that empty space is not nothing. The earlier version included a concept called a "cosmological constant." Empty space possibly has an energy of its own and more space can come into existence. Rather than becoming diluted as space expands, new space comes into existence to accelerate the expansion. Other ideas include the quantum theory of matter explanation and Quintessence, but none to date have provided an answer we can readily justify with current data.

Image highlights newly formed galaxies and galaxy clusters at the far ends of the Universe.
Image highlights newly formed galaxies and galaxy clusters at the far ends of the Universe. | Source

So What's Going On?

We know the Universe is expanding. We also know that the Universe is expanding at a faster rate than it was previously. We know that dark matter exists. Unfortunately, we do not know what the relationship between dark matter and dark energy is or if there even is one. We do not know exactly what dark matter is and we cannot explain dark energy with our current theories and suggested ideas. Although we have collected vast amounts of data in these areas, we do not have many answers. Our current explanations for the expansion of the Universe lies in dark matter and dark energy, but we know so little about them that we cannot guarantee future research will not lead us to a different conclusion. We have ruled out some possibilities, but far more data will be required to provided more detailed explanations.

Hub #18/30 for March Challenge

© 2012 Evylyn Rose


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      Giuseppe Rullo 5 years ago

      Dear Evylyn Rose, while reading your topic on "Dark matter and dark energy" I felt an urge to step out of my confort zone and put in my two cents worth. My humble opinion is that while scientists look for "dark matter" they will not find it! I believe that what they are looking for is not dark at all, but something so clear it is invisible. It may be a form of energy that makes up the unaccounted-for matter in the universe. This matter may decay in time, and show up in the visible universe were it accumulates to form new stars, and possibly cause the universe to expand. (Personal opinion only - no offence intended)

    • one2get2no profile image

      Philip Cooper 5 years ago from Olney

      Excellent hub Evylyn. There is still much we don't know about the universe and I suspect that although what we know is awesome...what we don't know is more awesome. Voted up!

    • Rhiannon Schaefer profile image

      Rhiannon Schaefer 5 years ago from Fort Wayne

      Very interesting. I've always found dark matter and dark energy to be an exciting thing to think about. You did a good job realaying the layman's terms.

    • profile image

      liam 5 years ago

      thank you =)

    • Evylyn Rose profile image

      Evylyn Rose 5 years ago from Colorado, USA

      hawkdad, thanks for the comment! :) I'll have to see if I can find a copy of that article. It sounds like it would be a fascinating read!

    • hawkdad73 profile image

      hawkdad73 5 years ago from Riverside, Iowa

      Great Hub.

      I read an article in the March issue of Discover magazine about Physicist Julian Barber "rewriting [Einstein's]rules of space, time, and gravity."

      Like your Hub, it's worth a read.

    • Evylyn Rose profile image

      Evylyn Rose 5 years ago from Colorado, USA

      Thanks for the comment and vote, one2get2no! :)

    • one2get2no profile image

      Philip Cooper 5 years ago from Olney

      Wow! Great stuff. Difficult to get my brain around it but I love anything to do with dark matter/energy. Voted up!

    • ib radmasters profile image

      ib radmasters 5 years ago from Southern California


      Thank you for the interesting hub and subject matter to stimulate my thoughts.

      On another thought, I have always had a problem with e=mcc

      As the definition for energy, and matter is illusive.

      Looking forward to reading more of your hubs.


    • Evylyn Rose profile image

      Evylyn Rose 5 years ago from Colorado, USA

      Kieran, I don't know that we have ruled out the possibility that something can travel faster than light; we just have yet to find anything that can! Einstein was genius for what we knew during his time. If he were alive today, I suspect he would be sitting back and laughing that we are still using some of his theories in light of data we have now. ;) Thanks for the comment!

    • Evylyn Rose profile image

      Evylyn Rose 5 years ago from Colorado, USA

      Vegas, thanks for the comment. :) I generally avoid writing on this topic area because it is so hard to talk about it in layman's terms. Not that I am an expert and some of the terminology as you go deeper into the research can make my head spin at first, but when you've studied it for years, it's hard to remember which terms made no sense in the beginning. I'm glad I was able to make it understandable. ;)

      ib, great comment! I agree with many of your points and many physicists will readily admit there is so much we don't know. I personally believe we are wrong about the BBT, or, at the very least, it is flawed. The problem is we have yet to find a suitable alternative that will cover what we can explain, much in the same way we are hesitant to completely throw out Einstein's theory of gravity in light of what we know about dark matter and dark energy. As more data and research continues, we will see many of our current theories become outdated or revised to incorporate the new observations. Considering how far we have come so quickly in just this last century (and subsequently the last 30 years) alone, it won't take as long into future decades to make even bigger leaps.

      Great point in using statistics! We can survey 1,000 individuals of varying background to provide a representative statistic for a whole society, but the data is truly only representative of those 1,000 individuals. Likewise, we have tons of data from observing the Universe, but it is still only representative of what has been observed thus far. All we can do is continue to update and expand our understanding of the Universe as we continue to collect more data.

      Thanks for the thought-provoking comment! :)

      scott, thanks for the comment and compliment. I agree. I love cosmology and other astronomy subjects!

    • profile image

      Kieran Gracie 5 years ago

      Thank you, Evylyn Rose, for this interesting glimpse into dark matter and dark energy. Surely these are the most exciting 'finds' in recent astronomical observations, and I find it intriguing that they might lead to revisions in relativity and quantum theory. Now, if Einstein can be wrong about that, perhaps it might be possible to travel faster than light after all?

    • scottcgruber profile image

      scottcgruber 5 years ago from USA

      Good hub! Very nice introduction to a fascinating subject. Cosmology is fun!

    • ib radmasters profile image

      ib radmasters 5 years ago from Southern California

      Nice hub and a lot of information.

      My personal opinion is that we don't have a clue, and the Big Bang Theory limits are ability to see other explanations of the universe.

      The Big Bang Theory doesn't account for a single event that had to precede it before it came into being.

      So based on the BBT we pigeon hole the rest of the theories in support of the BBT.

      Using the Doppler Effect to judge whether a fourteen billion plus universe is expanding is not really fact.

      We still don't have a Grand Unification Theory and that may be because we have already wrongly configured the basic units. So we cannot but these units together because we didn't have accurate plans in our universe kit.

      Entropy and Chaos is our universe, but is that the truth, or just our version of the truth.

      Making judgements about a universe that is suspected to be over 14 billion years, while we have only been looking at the universe for a few thousand years, is like looking at our moon for a few seconds and trying to make sense of what we see.

      What if the BB was merely a huge black hole that was still propelling energy into the universe, or that another black hole or some kind of pulling force was attracting our universe to it.

      I also think that because our Solar System has the results of objects colliding into the planet and moons in it, and that an Asteroid Belt still exists begs the question why does it exist?

      It would seem that the explanation given for the formation of the planets and their moons should have also covered the Asteroids. It is like there are unexplained Eddy Currents in our Soar System them are independent.

      While the BBT answers some questions, it generates other unsolvable questions. Maybe it is time to have the geniuses scrap it and start from scratch, and focusing on what may have caused a singularity. If there truly was a singularity as offered by the BBT, then we need to know whether that was the beginning of a new process, or the end result of another process.

      The multiverse theory also exists, but there is not much proof to support it. Again, I think that we have to redo our building blocks of the universe.

      I am not a fan of String Theory and its multiple dimensions. To me it is a black box theory where we try to surmise what we see, with what might be missing but unseen to get the same result.

      Math is great and it has done wonders for technology, but math also confuses what we see, and how we see it. Statistics is a great example, we put billions of pieces of information into computers, that we have a program, or programs to represent what it looks like, and try to make sense of it. Mathematically it is a correct representation, but it doesn't equate to reality. Just because you can represent this huge data doesn't mean that that representation is meaningful or accurate.


    • Vegas Elias profile image

      Vegas Elias 5 years ago from Mumbai

      I find this very informative and interesting. Well presented for the lay person to understand.