• Question: What is dark matter and dark energy?

    Asked by Noivette to Stu, Rob, Maheen, Euan, Deborah on 16 Jun 2016.
    • Photo: Deborah Prunty

      Deborah Prunty answered on 16 Jun 2016:

      Dark matter and dark energy are concepts made up by scientists to make their maths work. They know how the universe should work, but the maths just doesn’t seem to add up right. The universe should be heavier and contain more energy than we can find. Dark matter and dark energy are the missing bits that we haven’t been able to measure or find yet.

    • Photo: Euan Allen

      Euan Allen answered on 19 Jun 2016:

      Fantastic question Noivette!

      By looking at how galaxies rotate, and how planets and stars are being attracted to them, we can make a pretty good estimate of how much matter (mass) there should be present in the galaxy. The problem is, is that when we actually look at most galaxies, then we find that they don’t appear to have nearly enough matter that we can see. We therefore predict something called dark matter, which we know probably exists because of our observations of how the galaxy moves, but we can’t directly observe yet (although we’re looking).

      Dark energy is a similar thing, but now we are talking about the universe as a whole. We know the universe is expanding, and the rate at which it expands depends on how much energy there is in the universe. When we look to see how much energy there is, we end up counting less again. Dark energy is the chunk of energy left that we can’t see to find/see where it is.

      The crazy thing is that dark matter and dark energy make up the majority of the universe (92% is dark energy, 6% is dark matter, leaving only 2% for EVERYTHING we can see – suns, stars, galaxies, planets…). We have lots of theories as to what this dark energy or matter might be, and experiments like the Large Hadron Collider are working hard to see if these theories are true or not.

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