• Question: What is dark matter?

    Asked by 522bdta32 to Anna, George, Jodi, Rob, Stefan on 17 Nov 2014.
    • Photo: George Ryall

      George Ryall answered on 17 Nov 2014:

      Dark matter is matter in the universe that we can’t see, but still has an effect on the movement of other objects that we can see, through gravity.

    • Photo: Anna Scaife

      Anna Scaife answered on 17 Nov 2014:

      We don’t know 🙂

      The reason it’s called “dark” is that it doesn’t interact with any radiation directly – so it doesn’t absorb, reflect or emit light, or radio waves, or any other frequency of radiation. The only way we know it’s there is through its gravitational effect on things, which causes their movement to change.

      One possible explanation for dark matter is a hypothetical particle called the “axion”. Axions are particles that only interact very weakly with normal (i.e. non-dark) matter. At the moment they’re only a theory, but if they do exist then they *might* explain a number of open questions in particle physics, including dark matter.

    • Photo: Stefan Lines

      Stefan Lines answered on 18 Nov 2014:

      Matter that we can’t see through EM Waves (such as looking through a telescope). We can see its effect through gravity though. For example, galaxies rotate at an unexpected speed based on their mass – so we need Dark Matter to explain this.

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