- We first derived equation of motion of circular orbital using trigonometry to be taught the reasoning behind the equations we were using to better understand what we would ultimately be finding, which was whether Newtonian physics is incorrect or whether there is unseen matter that we are detecting in our universe.
- We applied equations that we were able to derive to the planets in our solar system to build a rotation curve in efforts to find the value of G – the gravitational constant in the formula F=GMm/r^2.
- We made these values logarithms to linearise the data and used this log/log plot to get values for rotation curve for gradient and y-intercept.
- We applied this same method to other systems such as the moons of Jupiter and Earth’s moon to check if this value was constant.
- We then approximated value of ‘G’, and got it very close (1st 3 decimal places) to 8*10^-11.
- We then covered a fair amount of electrodynamics while walking around UWA, learning that attraction between electrically charged things is equal to gravitational matter behaving as a wave, like electrons exiting quanta of light. This would become apparently useful on the following day.
Formulas learnt on the 2nd day:
- G= 8*10^-11
- F=GMm/r^2 , law of gravity. From our calculations on day 1, this seemed to work in the solar system. But does it work elsewhere?
- We learnt that internal mass is equal to gravitational mass, and Planck’s constant, h = 6.6*10^-34 J s, E=hf
- We learnt that light must be in packets of energy (photons), called quanta as suggested by Einstein. Energy of each packet is e=hf.
- What if each particle has a wavelength associated with it? p*landa = h/p
- 2*pi*r = n*landa = nh/mv
- We also found that when an electron is spinning, it has an electric charge associated with it, meaning it is magnetised.
- 1) Found radius of hydrogen electron
- 2) Velocity of electron
- 3) Kinetic Energy
- 4) Potential Energy
- 5) TME
- Log Radius, Log Velocity, log KE (to linearise and find equation)
- We used SRT via the internet to observe at different galactic longitudes (theta) the velocity of bodies of hydrogen and calculated the radius. Then found the mass given the radius.
- What we expected to find was the Newtonian model for the universal law of gravity which should demonstrate inverse-square relationship, as we found beforehand with bodies such as the solar system, and Jupiter’s moons. Galactic data from hydrogen emission does not show this curve, but a very different curve either suggesting that Newton’s law of universal gravitation is wrong or that there is unseen matter in our universe.
- The following steps were used to write a program for the SRT to run by over time. It was important to note the SRT stowed itself (shut down) at 8am and 2pm every day.
- Start with a stow, end with a stow.
- Write program for wider bandwidths. Light overlap to stitch all readings together. Equal time intervals are important for recording data at each bandwidth interval.
- Give galactic coordinates
- Recording begin
- Wideband observation
- Recording end
This would record data over a set time frame according to the instructions at different galactic longitudes.
- Travelled up to Gingin to observe radio telescope we had been using the previous day.
- Dusted cobwebs off of the camera.
- Nothing visibly wrong with the telescope.
Travelled up to Pawsey Supercomputing Centre and received a tour of some of the computers in the centre and the sorts of roles the computers were utilised for, one of which was used for multiple purposes for astronomy research. We then helped in removing useful components from disused units valued at $50 000. We then tested a physics simulation on a small pi unit.
On the final day, we observed the data which was recorded by the SRT from day 3. However, there was a large amount of interference and so this data was unusable. We were given some previous data to work with instead. The data was incredibly comprehensive, as this was apparent when we ported it onto an excel spreadsheet. However this was good as it gave us a very defined curve. We graphed a frequency to intensity graph with this data for each of the different frequencies, and then combined these graphs to form a very large graph of the whole curve. Using this we could find the max velocity of mass for that point and then found the radius between the galactic center and that point. This process took all day for the single point, and if we had more time we would have found a few more to test our accuracy of results. This curve that we produced made 2 things apparent: either Newton’s law of universal gravitation was wrong or that we had found evidence for dark matter. I absolutely recommend ICRAR work experience, as it was such an amazing and fascinating few days, and I came out of it learning much more than I though I would, and it has inspired me to possibly take up an occupation in this field in the future. All the staff were extremely friendly and helpful and our teacher, Matthew always offered help and suggestions where needed. The other students were very friendly as well, which made this an all-around fantastic week.