• Question: What is Dark Energy and Dark Matter and could there be life made of dark matter?

    Asked by michaelwhu to Adam, Geoff, Rob, Sheila, Suzie on 21 Mar 2011 in Categories: .
    • Photo: Adam Tuff

      Adam Tuff answered on 20 Mar 2011:

      At the moment – no one knows. Dark matter I know more about as I’ve done some research on it – basically there is a lack of observable matter in the universe from the observations of the motion of visable matter in galaxies. The two most popular theories for dark matter are MACHOs (MAssive Compact Halo Objects) – things like dead dwarf stars / neutron stars (maybe even quark stars) of very low visabilities. The other are WIMPs – Weakily Interacting Massive Particles – like the Neutrino. We have not identified the mass of these particles, and these could well make up the missing mass because of the countless numbers permeating the cosmos.

      Dark energy is a little more difficult, as this supposedly makes up ~ 75% of our universe – at the moment it’s believed to be what’s driving cosmological expansion – there are a host of ideas that have been put forward for it’s origin (things like string theory, brane theory) etc…but all are highly theoretical.

      I’m not sure about life existing in dark matter or dark energy form – would make a great idea for a sci-fi novel or film though (I promise not to steal it!)

    • Photo: Suzie Sheehy

      Suzie Sheehy answered on 20 Mar 2011:

      Hi there. This question shoots right at the heart of many physicists: it’s kind of embarrassing. For all our centuries of study of how the world works, we still can only account for a few percent of the mass of the Universe!
      But it’s not because of any failing on our part, the difficulty is not being able to observe it!! Dark energy is thought to make up 73% of the universe and Dark Matter 23%… so we only know what about 4% of the Universe is!
      We currently don’t know what they are made up of, though we have some good candidate particles from theories like Supersymmetry – we’re trying to observe these particles all the time both at the Large Hadron Collider and with other experiments. The problem is that they are thought to only interact with matter very weakly, which makes them really hard to spot!

      I personally don’t think there could be life (as we know it) made of dark matter, but until we know what it is and know more about it, my answer is purely speculation!

    • Photo: Sheila Kanani

      Sheila Kanani answered on 20 Mar 2011:

      If there was life made from dark matter we couldn’t see it! 🙂
      Dark matter is exactly that, matter that we can’t see. It must be there though, because it affects the universe.
      I think of dark energy a bit like anti-gravity; instead of pulling things together it pushes them apart!

    • Photo: Robert Simpson

      Robert Simpson answered on 21 Mar 2011:

      The idea of dark matter has come about as a way of explaining the fact that objects in the Universe are more massive they look to be. We can see light bend around distant galaxy clusters in ways that suggest there is X mass in those clusters, but we see less than X when we add up all the stars and dust in those galaxies. Our own galaxy rotates in a way that suggests there is a lot more material in it than we can see.

      So dark matter is just that – its matter than is totally dark. Unless we’ve got huge parts of physics wrong, dark matter is out there even if we can’t see it.

      Dark energy is different. All the galaxies we see in the universe shouldn’t be moving apart in the way that they are. If you take all the forces in the universe that we understand then we ought to see those galaxies moving toward each other or standing roughly still. So we essentially invoke a new, unknown, ‘dark’ energy that is driving all the galaxies apart.

      The crazy part is that dark energy makes up most of the energy of the universe, about 70%. Dark matter, too, is much more common than matter and makes up another 25% of the universe – the bright, normal matter that we are made of, and all the stars in the sky too, is not so ‘normal’ at all – it makes up less than 5% of the whole universe.

      Could there me dark matter aliens out there? Maybe. It depends what dark matter turns out to be.

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