Below are some questions asked to us via the website form, and also via the text form and via video on the app on the buses. We have done our best to reply to them in full! 🙂

What is dark energy?
– Emily, 20

Objects in the universe move through space according to the laws described in Einstein’s General Theory of Relativity. This theory states that the matter in the universe moves according to the Einstein equation $G_{\mu\nu} = 8\pi GT_{\mu\nu}$, where $G_{\mu\nu}$ describes the curvature of spacetime (a four-dimensional quantity composed of the three spatial dimensions and the dimension of time) and $T_{\mu\nu}$ describes the matter in the universe. Effectively, this equation shows that the matter content of the universe changes its curvature, which in turn affects how the matter moves through space. This is described succinctly by the John Archibald Wheeler quote “Spacetime tells matter how to move; matter tells spacetime how to curve.

There is a possible term in the equation which depends on a constant value $\Lambda$. This is the “cosmological constant” (what we now think of as being dark energy). Applying the equations to the entire universe with this dark energy term included produces an acceleration in the expansion of the universe, of the sort that has been observed from the velocity of galaxies moving away from us. Thus, dark energy means that the universe is not only expanding, but is accelerating outwards.

If the dark energy term is sufficiently large, it can overcome the gravitational force of all the matter in the universe to such an extent that the universe will expand faster and faster until matter itself starts to break apart due to the tremendous force from dark energy. This is called the “big rip” and is a possible end of the universe. Don’t worry though, it won’t happen for about 22 billion years!
– Andrew

Are there new states of matter at ultra high temperatures and densities?
– Harriet, 20

Most people know of three states of matter: solid, liquid, and gas. At high temperatures, there is an additional state called plasma.

This occurs when the electrons are separated from the nuclei. Under the right conditions, long-range electromagnetic fields dominate and the system becomes very electrically conductive. This is a plasma. Plasmas can be found throughout the universe in stars and interstellar material, as well as on Earth, both naturally (in lightning) and artificially (in plasma TVs).

Additionally, there is a theorised second type of plasma that would occur at about 2,029,000,000,000 oC, in which the nuclei of the atoms break apart and the sub-nuclear particles quarks and gluons are free to move around individually (something that is forbidden at lower temperatures according to the laws of physics!).
– Andrew

Will the increase in integrated luminosity improve our statistical likelihood for confirming the mass of the lightest neutralino?
– Tia, 21

We’re finding a physicist to answer this question for you!
– A. Physicist

What planet are we on?
– Joe, 22

Planet Earth – the only celestial object known to harbour life.
– Annie

What is the meaning to life, the universe, and everything?
– Alex, 20

42!
– Annie