Saturday afternoon started with Andrew Pontzen of University College London asking Does Dark Matter Exist? and going on to say why he thinks it does. Andrew laid out the main reasons to think that 5/6th of the mass of the Universe is invisible. In no particular order:
- there is not enough visible mass in galaxies to stop them flying apart.
- The gravitational lensing of distant galaxies needs 5 times more mass in the foreground galaxies than we can see.
- Where galaxies collide there is something which passes through without interacting with all the normal matter.
In each of these cases there needs to be 5 times more matter than we can see to explain what is happening and it is this consistency which points to us being on the right track.
The current theory is that Dark Matter is a particle which is invisible and untouchable. Initially this seems strange but if you consider that ordinary matter is only visible and touchable because of electromagnetism it becomes clear that Dark Matter may be a particle which does not feel the force of electromagnetism. We already know of particles which do not feel electromagnetism, for example the neutrino. So if it does not feel electromagnetism which of the other three forces does it feel. The current view is:
- It does feel gravity.
- It may feel the weak force.
- It cannot feel the strong force because if it did pretty much everything would be radioactive.
So far all attempts to find Dark Matter have failed. So are we looking for the wrong thing. Andrew’s view is not. He points to the fact that Einsteins Field equations match exactly what Planck found from the cosmic microwave background. He points to this graph as confirmation, in his view that we are looking in the right place.
The theory matches the observations. All we need to do now is find the stuff!
Following this Hugh Hudson from the University of Glasgow outlined a project to crowd source images from next year’s solar eclipse to produce a mega movie of the solar eclipse which would allow for study of the solar corona in unprecedented detail. Google will contribute the computer grunt whilst work is underway to develop a smartphone app which would help undertake this work. There is a lot yet to be done but it looks like an interesting project . More detail can be found on their website at http://www.eclipsemegamovie.org
The next speaker was Lewis Dartnell from the University of Kent on the subject of What Makes a Habitable Planet. Lewis started by talking about what we mean by life. He pointed out that on Earth extremeophiles live in the most hostile of conditions. In fact extremeophiles can be found living in the conditions that we find on Mars Venus and Europa. So we already know that the conditions on those worlds can support life although whether they do is a different question.
Whilst we do not really know the conditions in which life originally evolved on Earth we now have a very good idea of the conditions in which it can survive. But when we look for worlds which may have life another factor is being able to support that life over very long periods to allow it to evolve. So, for instance, when life was first evolving on Earth, Mars was actually a very similar planet. Although it was on the outer edge of the habitable zone it had a thick atmosphere and flowing water on its surface. However because it was much smaller it lost its magnetic field quite quickly and with that gone the solar wind stripped away it atmosphere and as a result it lost its flowing water. So conditions not only have to be right they also have to stay stable over geological timescales.
Lewis finished by saying he thinks we are on the brink of not only finding one Earth twin but that we will find many over the coming years and that the missions like Twinkle and its successors will be able to tell us if life exists on these planets through the spectroscopic analysis of their atmospheres.
The final talk of the day came from John Spencer on some of the early results from the New Horizons mission to Pluto. We have covered this fairly thoroughly in recent meetings and there was really no new material covered in John’s talk so I will not cover it at any length here although some of the high resolution images he had to show were quite stunning.
With that Astrofest ended for another year.