Riley Forward

### day 1

Upon arrival at the ICRAR building in UWA, the three other students and I were given a tour of the building and introduced to some of the students and staff in the facility at the time. After this brief tour, we were shown to our room, introduced to Mathew (the astrophysics course coordinator) and quickly put on some mathematical derivations for orbital mechanics. Later, after we got briefly disoriented trying to find food (and the way out), we did some further research on the orbital period and radius of the planets around the sun and substituted those values into our derived equations to solve for tangential velocity and centripetal acceleration (I very much enjoyed the mathematical derivations to find the equations that describe orbital motion). Once we had collated all of our data we plotted the velocity curves (radius on the x, and velocity on the y), acceleration curves and their respective log-log plots (the log-log plots are so we can easily find the proportionality constants between the x- and y-axis). After this, and some time talking among ourselves about our interests, we applied the same equations and plotting methods to the Jupiter and Earth systems, seeing a, seemingly, consistent relationship between both axes (an inverse-square relationship for anyone who is interested). Then we used newtons second law (F=ma) and our previously derived equations to derive Newton’s law of universal gravitation (this was very satisfying watching all the equations fall into place). Now as we approach the end of the day we went outside for some air and covered, well, the history and appropriate applications of Electrodynamic theory and Quantum physics. From Bohr’s model of the atom to the implications of Schrodinger’s equation on the wavelength and frequency of neutral hydrogen, we had a busy walk.

### Day 2

On our second day, we started where we left off- talking about the implications and mathematical derivations of the different orbital states of neutral hydrogen. Using equations like the Plank-Einstein relation and Coulomb’s law, we were able to calculate the energy of the electron at different orbitals, and therefore, the changes in energy from an excited state (higher ‘orbits’) to the ground state. Then we revisited the spin of the subatomic particles in neutral hydrogen (1 proton and 1 electron), and we found out that there is an even lower state than both particles having a spin in the same direction (and on the ground state), where the spin of the electron flips and emits energy in the form of a photon (this emission occurs, on average, every 1 million years). This change in energy, using E=hf (Plank-Einstein relation), can give us the frequency (‘f’) of the light that is emitted by the electron (which happens to be 1420.4 Mhz). Then we had a tiny lunch break (tiny by choice) and went back to work. Now we know what to observe, we need to go out and observe it. So, using the SRT (small radio telescope) in Gingin, we looked at the emission spectrum in and around the range of 1420.4 Mhz. We knew that, because of relative Doppler shifts, not all of the light would be at precisely at that frequency. With this, we can calculate the velocity of the hydrogen relative to LSR (our Local Standard of Rest). Today the calculation was done automatically and graphed for us. Using this data and our equations derived on the first day, we were able to calculate (using some simple trigonometry) the radius of the hydrogen from the centre of the galaxy. Now we have radius and velocity; we can plot a rotation curve, such that the curve observed is the relationship between the radius of an orbiting object and its velocity. We quite quickly noticed that the observed curve was not an inverse square relationship, and we pondered the implications of this (being that either Newton’s equations of gravity are wrong or there is mass we are not seeing- dark matter). As you can see I get a bit excited about science, as you should in such an interesting field.

### Day 3

Today is the day we go to Gingin to look at the SRT and the gravity museum. First, we came to UWA so that we could write a script for the SRT to run (it was a wideband observation at different longitude values). Then we got into the car and took the long drive to Gingin. After the hour drive there, we stretched out our legs and went to go sit inside for some lunch. Being given some tokens, we went up the rather high, and rather windy, leaning tower; for some sightseeing and dodgy selfie attempts. Then after coming back down, we explored the Gravity Discovery Center, some of us spinning themselves up to 2.5 G in the higher gravity simulator (I am pleased to say no one was sick), and looked at one of the early models of a gravitational wave detector. Next, we got in the car for a short five-minute drive to the SRT and associated sleeping quarters/ office space for the engineers and staff working on site. Mathew explained some of the components and features of the impressively simple telescope and then we took a photo and got on our way.

### Day 4

Today we, after several attempts, ordered an uber and went to the Pawsey supercomputing centre for a tour and other interesting activities. When we got there, we went inside, sat down, and discussed the features and applications of their supercomputers (including the up-and-coming replacement they are having to all of their computers in the coming 18 months). Then we’re given the opportunity to disassemble some, ex, \$50,000 computer cells they used to use. We removed the RAM sticks and the cores and placed them in some anti-static packaging for them to use as spare parts. Next, we were taken by Ann, the education and training manager at Pawsey, to the CSIRO building and we were given an introduction to Mini-Magnus (named after one of the larger supercomputers) which is a set of 4 Raspberry Pies, all running in parallel. Then we were shown a fluid mechanics simulation and allowed to use the PS4 remote, simulating a mouse and keyboard (it’s a long story), to control a ball inside a fluid Simulator. The purpose of this simulation was to show you visually how adding different threads (pseudo-cores) allows for better processing speeds, and therefore, higher fps (frames per second). With the Simulation running at a standard 60 fps and being able to adjust the constants that run the physics model (elasticity, gravity and other variables), we – obviously- tried to break it. Getting the fps down to 10 (a new record they said) was quite entertaining, but we were unfortunately not able to break it. After this (probably beneficial) failure, we went into a conference room and ate our lunch. In the same conference room, we participated in a zoom call, run by the students at CSIRO and PAWSEY, which was about purpose, problem-solving, fixed and growth mindset (which we had some very interesting conversations about) and the GROW model (Goal, Reality, Options and Way forward). After discussing the applications and implications of both fixed/growth mindset and the GROW model, we were able to talk to some of the Pawsey mentors about their experiences at Pawsey/ university and how they were able to get the opportunities they got, the ups and downs of university life, and some generally helpful advice on how to proceed. Then, after a very busy day, we got in an uber and came back. Inside the uber ride, and at Pawsey, we had some very interesting conversations on education, religion, politics and psychology (as you do).

### Day 5

After a little chat about how upset we all were that today was our final day, we talked to Matthew over Zoom on what we were going to do today. We discussed how we’re going to analyse the data we have been collecting over the past couple days, and what to graph to be able to infer the gravitational composition of our galaxy (assuming the validity of Newton’s laws of course). After working on this for a couple of hours we were invited to the Friday recess all the staff have, being given the opportunity to drink some coffee, eat some food and talk to some of the people who work there. After awkwardly introducing ourselves to the whole staff and eating some food by ourselves over in a corner, we got chatting with Dr Karen and Cass about our experience there and what we were doing. Then, of course, this conversation spiralled into talking about the flaws in modern education systems. After finishing this very interesting conversation and taking some photos, we all went back to work. Working on the data was very fun (frustrating, but fun), especially when all the work just fell into place and you see all your work pay off. As we approach our 4 pm finishing time we start to rap up our data analysis and discuss the general results we are seeing. Then we chat among ourselves for a while, discussing future opportunities and activities in the astrophysics field until it was time to finish up.

Having work experience at ICRAR was genuinely one of the best experiences. Talking to professionals and like-minded individuals on such an interesting topic as dark matter, and space in general, was an experience I won’t forget. It most definitely confirmed my intentions in pursuing a career in astrophysics and expanded my curiosity in the nature of the universe and the tools we use to probe it. Any student looking for some exposure to the ins-and-outs of research/ astrophysics, a work experience program like this is one not to miss out on.