Well Hartlfest is over, and we had a cloud free night to observe the moons of Jupiter, but we should first review the calendar of upcoming events and then do some more review of Hartle's No-Boundary Proposal, which has been a very productive exploration of how to explain the big bang without the usual drawbacks of the singularity predicted by general relativity.
All the meetings and conferences in this calendar update are free and are conducted here locally in southern California. Many of you will attend the free OCA general meeting where we will hear about the search for exoplanets. If you are looking for other scientific meetings check out the other two events in the list below which cover free weeklong conferences, both at Caltech. These are serious scientific conferences but they are free and the website says "all martians are welcome", but you should register if you plan to go. So check out the events. I have been to the international Mars conference before and found it interesting and mostly comprehensible to the non-expert. See you there for at least part of the sessions.
- June 14 -- OCA General Meeting at Chapman University (web: http://ocastronomers.org/)
- July 15-19 -- NASA 2019 Saga Exoplanet Workshop: Astrobiology for Astronomers at Caltech (web: http://nexsci.caltech.edu/workshop/2019/)
- July 22-25 -- Ninth International Conference on Mars at Caltech (web: https://astrobiology.nasa.gov/events/ninth-international-conference-on-mars/)
Finally, the clouds went away last night and having remembered that Radio Amateur Ham and OCA, Marty, had reminded us that Jupiter was in opposition and will appear very bright in the sky. So, this finally was a chance to take out the camera and tripod and get an image of Jupiter and moons. The DSLR image below was taken with 1/30 second, so the moons would all be visible, even though Jupiter is way overexposed. When the shutter speed was decreased to 1/125 seconds, the moon Calisto, was too dim to see. I thought of going to shorter exposure times to see if any details of Jupiter's band structure and possibly the red spot would show up, but the camera battery died.
The dead camera battery was not supposed to happen. I thought I had enough juice left, but I took 10 times as long just to point the camera at Jupiter than what I imagined. Jupiter is very bright now at magnitude about -2.6. Very easy to see with naked eye, but I could not find it or see it in the camera Liveview screen. What was going on. Ok, ok, I did remember to take off the lens dust cover! I checked exposure settings and all sorts of things but I just could not see Jupiter at all. Now for the lesson learned, because I finally discovered, after actually pointing the camera at a nearby house light, that I had forgotten that the solar filter was still in place.
Lesson learned: Don't forget that you might have left the ND 100000 filter on the camera the last time you used it!
Anyway, it was good to see the moons. Thanks for the reminder, Marty!
|Jupiter and moons are easily visible in this 600mm, 1/30 second DSLR overexposed image (Source: Palmia Observatory)|
These four moons, out of 79 total moons, are all in the same orbital plane and the screenshot from the Sky and Telescope iPhone app below shows the names of the moons. The orientation of the orbital plane as seen from the Earth is really aligned about 45 degrees to the horizontal, but the image has been rotated to match up with the screenshot. So, the moons from left to right are: Ganymede, Europa, Io, and Callisto.
|Sky and Telescope iPhone app screenshot shows current location of Jupiter's moons (Source: Palmia Observatory)|
It is interesting to plot the orbits of the moons by taking images, at say daily intervals, for a period of 2-3 weeks. This Resident Astronomer collected dozens of images back in and plotted the angular separation of the moons from Jupiter. Then you can get a sense of the orbital periods of the moons and track each moon during its orbit around Jupiter. The original plots of Jupiter and moons is shown in the March 21, 2016 post. You can search for the post or for convenience, just click on the post reference: http://www.palmiaobservatory.com/2016/03/general-relativity-at-100-celebration.html#more. It is neat to see how soon the motion can be seen and identified as orbits around Jupiter and how the ordinary astronomer can get started in collecting the observations!
Finally, let's return to some more details of the interesting concept of No-Boundary Proposal, developed o solve some aspects of the singularity problem. The following video describes the NBP with interviews with Hartle, Hawking and Hertog. It is one of the best videos I have seen on the topic.
|Very good video explaining the No Boundary Proposal (Source: https://www.youtube.com/watch?v=Ry_pILPr7B8&app=desktop)|
Many of the speakers at Hartlefest, celebrating Hartle's 80th birthday, talked about the influence of the 1981 paper on the wave function of the universe. I didn't quit realize it at the time, but the video here went into more of the details of the No Boundary Proposal (NBP) and its historical significance. From the 1920's onward, after Friedman and Lemaitre developed the expanding universe from the primal atom or singularity, Hawking and Penrose proved that the big bang singularity was a prediction or outcome of general relativity. But no physicist likes singularities. So after Hawking, recognizing as many other physicists did at the time, that quantum mechanics would be necessary to really explain what was going on at the big bang. Hawking then introduced quantum mechanics into the theory of black holes and found that the black holes would eventually evaporate because of emission of Hawking radiation.
Then with the publication of the 1981 paper, Hartle/Hawking showed that there was a possible way out of the singularity problem but still incorporating the big bang. Many physicists, including Thomas Hertog, KU Leuven, in Belgium, who is the third member of the triad in the video, have been working on understanding the NBP ever since. Hertog explained that NBP leads very quickly to the possibility of the multiverse. He goes on to explain that even though these extra universes are not directly observable, this does not mean it is not science because the NBP leads to direct predictions that can in principle be observed in this, our, universe and so the theory does make verifiable predictions.
So, what exactly is the No Boundary Proposal? Hmm, maybe the best answer is to watch the video, but I can try to summarize at least the part that I sort of understand and hope to more fully understand with more study. I am still trying to work my way trough the Hartle/Hawking 1981 paper.
It all goes back to the shuttlecock description of the big bang. So at the big bang there is not central point from which everything expanded and the curved beginning of the shuttlecock removes the singularity. This smooth surface is derived by considering solutions to the wavefunction attached to the whole universe. We need to keep in mind that this wavefunction is not like the ones we study in quantum mechanics, where we as experimenters stand outside the wavefunction being studied, but the wavefunction at the beginning of the big bang includes us and everything else inside the wavefunction. There are no outside observers at the big bang!
So then Hartle/Hawking use the Feynman sum over all pathways and histories approach, not the Copenhagen interpretation of quantum mechanics, to calculate the evolution of the universe. This summation approach then does not include any "boundary" other than the final part where we are observing the universe. So the universe start off with only spatial expansion and it was only "later", whatever that can mean, given that time emerged as part of the shuttlecock illustration. Hmm, at least I think that is what the term means! Ok, ok, so we see right away how and why it is necessary to include both general relativity and quantum mechanics to get some idea about what this is all about. Whew, that is it for me; check out the video for yourselves and see how you interpret the NBP and what I probably missed!
Finally, for all the physicist wannabes out there, who are trying to understand at least the general relativity portion of the NBP, I finally found another great solutions manual that is of great value when trying to learn and understand general relativity. This student's manual follows the problems used as examples in Bernard Schutz's "A First Course in General Relativity", which I also use as a very good introduction to GR. Now, in order to really come to understand GR, not just by reading the texts, but by actually doing some of the calculations, this student's manual really helps one to get over the hurdle of actually doing the math. If you are trying to study GR, especially own your own outside of the regular classroom, get this book!
|Every physicist wannabe can benefit by Robert Scott's Student Manual|