Weighing the Sun with five photographs


Hugo Caerols, Felipe A. Asenjo
With only five photographs of the Sun at different dates we show that the mass of Sun can be calculated by using a telescope, a camera, and the third Kepler’s law. With the photographs we are able to calculate the distance from Sun to Earth at different dates along four months. These distances allow us to obtain the correct elliptical orbit of Earth, proving the first Kepler’s law. The analysis of the data extracted from photographs is performed by using an analitical optimization approach that allow us to find the parameters of the elliptical orbit. Also, it is shown that the five data points fit an ellipse using an geometrical scheme. The obtained parameters are in very good agreement with the ones for Earth’s orbit, allowing us to foresee the future positions of Earth along its trajectory. The parameters for the orbit are used to calculate the Sun’s mass by applying the third Kepler’s law. This method gives a result wich is in excellent agreement with the correct value for the Sun’s mass. Thus, in a span of time of four months, any student is capable to calculate the mass of the sun with only five photographs, a telescope and a camera.
Read more https://arxiv.org/pdf/1906.12272.pdf

FCC-ee: Your Questions Answered

This document answers in simple terms many FAQs about FCC-ee, including comparisons with other colliders. It complements the FCC-ee CDR and the FCC Physics CDR by addressing many questions from non-experts and clarifying issues raised during the European Strategy symposium in Granada, with a view to informing discussions in the period between now and the final endorsement by the CERN Council in 2020 of the European Strategy Group recommendations. This document will be regularly updated as more questions appear or new information becomes available.

Baseline FCC tunnel layout with a perimeter of 97.5 km, and ptimized placement in the Geneva basin, showing the main topographical and geological features.

Read more at https://arxiv.org/pdf/1906.02693.pdf

A quick how-to user-guide to debunking pseudoscientific claims

Maxim Sukharev
Have you ever wondered why we have never heard of psychics and palm readers winning millions of dollars in state or local lotteries or becoming Wall Street wolfs? Neither have I. Yet we are constantly bombarded by tabloid news on how vaccines cause autism (hint: they do not), or some unknown firm building a mega-drive that defies the laws of physics (nope, that drive does not work either). And the list continues on and on and on. Sometimes it looks quite legit as, say, various natural vitamin supplements that supposedly increase something that cannot be increased, or enhance something else that is most likely impossible to enhance by simply swallowing a few pills. Or constantly evolving diets that sure work giving a false relieve to those who really need to stop eating too much and actually pay frequent visits to a local gym. It is however understandable that most of us fall for such products and news just because we cannot be experts in everything, and we tend to trust various mass-media sources without even a glimpse of skepticism. So how can we distinguish between baloney statements and real exciting scientific discoveries and breakthroughs? In what follows I will try to do my best to provide a simple how-to user guide to debunking pseudoscientific claims.
Read more at https://arxiv.org/ftp/arxiv/papers/1906/1906.06165.pdf

Exploring Gravitational Lensing

Einstein’s derivation of the lensing equation, solution, and amplification in AEA 62-275 (Albert Einstein Archives, The Hebrew University of Jerusalem, Israel)

Tilman Sauer, Tobias Schütz
In this article, we discuss the idea of gravitational lensing, from a systematic, historical and didactic point of view. We show how the basic lensing equation together with the concepts of geometrical optics opens a space of implications that can be explored along different dimensions. We argue that Einstein explored the idea along different pathways in this space of implication, and that these explorations are documented by different calculational manuscripts. The conceptualization of the idea of gravitational lensing as a space of exploration also shows the feasibility of discussing the idea in the classroom using some of Einstein’s manuscripts.
Read more https://arxiv.org/pdf/1905.07174.pdf

Einstein’s biggest mistake?


Gary J. Ferland
What, if any, was Einstein’s biggest mistake, the one most affecting our physics today? There is a perhaps apocryphal story, recounted by George Gamow, that he counted his cosmological constant as his biggest blunder. We now know his hypothesized cosmological constant to be correct. His lifelong rejection of quantum mechanics, an interesting side-story in the evolution of 20th-century physics, is a candidate. None of these introduced difficulties in how our physics is done today. It can be argued that his biggest actual mistake, one that affects many subfields of physics and chemistry and bewilders students today, occurred in his naming of his A and B coefficients…
Read more at https://arxiv.org/pdf/1905.09276.pdf