Tag Archives: astronomy

The time is out of joint: Chris Impey on the tick-tick-tock of the stately clock

Steven Weinberg wrote a famous book, “The First Three Minutes” on the early stages of the universe.  The same universe became transparent to light some 370,000 years later.  There are other landmarks in post-Big Bang time going down to bewildering fractions of a second.

But the early universe was very hot, very dense, and gravitationally very different from the comfortable-to-us 1 g we experience today on the surface of the earth.  Einstein has convincingly shown that spacetime is accordingly divorced from that human experience.   Clocks, for example, are affected by gravity and satnav constellations have to take this into account.  Did the first three minutes flow the same way three minutes flow in the here and now?  I sent that question to Chris Impey’s online office hour and he kindly answered.  It is a tantalizing response and one that will require substantial further study to fully appreciate – perhaps finally diving into the guts of GR.   It makes me wonder even more intensely why we anthropomorphize those intervals the way we do.

Youtube Channel: Astronomy State of the Art

Composer Toru Takemitsu has set the general idea to music.

Youtube Channel: Orquesta Sinfónica de Xalapa

 

Low-key Relativity: skydivephil on gravitational waves, the Universe, and everything

The mere detection of gravitational waves two years ago was cause for celebration and, for those of us skeptical of LIGO, eating of crow.  Now gravitational wave detections regularly cue electromagnetic observatories on the ground and in space with tighter integration to come.

Youtuber skydivephil puts the camera on several researchers active in developing the next generation GW systems and the ever more ambitious cosmological probing that these observatories will enable.

Youtube channel: skydivephil

Skydivephil and the unnamed narrator are self-effacing providing few details about themselves, not even their names in the nonexistent credits.   They also have enviable access to many leading physicists and institutes, largely on the theoretical side.   The style is simple: Let the speaker speak.  It is a refreshing antidote to the modern space documentary which highlights the doom-and-gloom with an explosion and visual effect every fifteen seconds.   Whatever one may think about string theory, loop quantum gravity, or their alternatives, it is refreshing to hear about them from the purveyors.  Here’s the “Before the Big Bang” playlist with an assortment of views on modern cosmology (note that the episodes are in reverse chronological order.)

 

Theme and Variations: Nahre Sol adapts and explains ‘Happy Birthday’

Pianist Nahre Sol delightfully explains sixteen levels of pianistic complexity in about ten minutes.  That doesn’t mean there are only sixteen but, damn, what a lower bound for the recreational pianist to aspire to!

Youtube Channel: Wired
and the separate Nahre Sol Youtube Channel

Sol is in good company.  Here are Mozart’s Variations on “Ah, vous dirai-je, Maman” which we know as something else.

Youtube Channel: Canacana Family

 

Misnomers: Dr. Srinivasan on Mostly Neutron Stars

It took me a year and an email to understand how merging neutron stars could generate heavy elements.  For this you need protons and from where do these protons come.  The year was for intermittent research and the email due to failing in that research.  As it happens, neutron stars are chock full of particulate goodness, far more than their name implies.   On the one hand it is good to know how it works, on the other hand it shows that my research skills could use some improvement.

Dr. G. Srinivasan, Researcher Emeritus from the Raman Research Institute explains the beaks and gizzards of these dense objects in great detail.   His 12 part lecture series “A Random Walk in Astrophysics” is also available.

Youtube Channel: International Centre for Theoretical Sciences

Horizon Event: The big EHT reveal

The Event Horizon Telescope team announces its major discovery following two intense and quiet years of data analysis on top of a longer period of development.   A nice testament to aperture synthesis and international collaboration as the rest of the world spirals into madness.  Damn!!!

Youtube Channel: National Science Foundation

Context for the interested public:
Youtube Channel: Sixty Symbols

 

Where are they now?: Carol Meier on Voyagers 1 and 2

Narrator Carol Meier has a meticulously researched, splendidly detailed, and wonderfully delivered update on the twin Voyager spacecraft and their epic journey of discovery from Pasadena to the outskirts of the solar system.  It isn’t clear if this is a commissioned piece or one she did on spec.  It is engrossing either way.

Youtube Channel: Carol Meier

Calling the shot: Brian Metzger on kilonovae

Soon after LIGO‘s first detection of a black hole-black hole merger, the astronomical community was hinting about a potentially more scientifically  exciting event within the interferometer’s grasp: The merging of two neutron stars. When two dark objects coalesce, the product is unsurprisingly dark. Colliding neutron stars on the other hand might emit light of some kind and the collision product need not necessarily be a black hole. More intriguingly, so-called kilonovae resulting from neutron star collisions have been proposed as the actual origin in our universe of many elements heavier than iron, challenging the conventional wisdom of these coming from supernovae.

Here’s a prescient talk by Prof. Brian Metzger of Columbia University and coiner of the term ‘kilonova’ on the consequences of neutron star binary mergers. He discusses their signatures in the gravitational wave record and across the electromagnetic spectrum to their ultimate role in nuclear synthesis. Given at Harvard on 16 March 2017, it is quite accessible for a technical colloquium presentation. A mere five months later on 17 August 2017, LIGO and its European counterpart VIRGO indeed detected the merger of two neutron stars and set of a flurry of observational activity across the globe and in space which confirmed at least qualitatively the predictions by Metzger and his group.

The details are still confusing.  For example, we can assume that it takes a long time for two neutron stars to form, presumably from the death as a supernova of each of a large, but not too large, binary pair.  These violent events will eject a lot of material into the interstellar medium.  The neutron stars then spiral slowly and combine, releasing a lot of neutrons to stick to light elements, transmuting them up the periodic table through the r-process.  But, where do these light elements come from if the ejecta from each of the progenitor stars has had a very long time to spread? (*)

Harvard’s Edo Berger has a concise summary of the multimessenger gold rush incited by the event in a special issue of Astrophysical Journal Letters.  Many of the papers are free to download.  As an aside, I was acquainted with Edo when he was an undergraduate physics student at UCLA while I was a researcher in the same department.  I had no idea then he’d become one of the Dukes of Earl of  high energy astrophysics.

(*) Addendum 20 April 2019: After a year of futility in not finding an answer to this question, I emailed Prof. Metzger and asked.  In a prompt and gracious reply he said that the ejecta from the merging neutron stars create the seed nuclei required for the r-process.  There are sufficient protons (10-30%) in the ejecta to form nuclei of mass number ~100 within milliseconds.  These then absorb further neutrons within the constraints of beta decay to create very heavy elements within a few seconds.  So,  it seems that neutron stars aren’t neutrons all the way down!

30 May 2020: New video source; prior channel was deleted.

Youtube Channel: CfA Colloquium

 

Youtube Channel: Kowch737

 

Space Music: Paul Novros accompanies the universe

The documentaries below were made in the 1970s by Lester Novros, then a professor at the USC film school where his students included George Lucas.  The understated elegance of these films is nicely framed by Paul Novros‘s music.  The younger Novros is a professor of jazz at CalArts.  I asked him whether he had any soundtracks available.  He was pleasantly surprised to be reminded of the work but has no separate recordings or scores.

Lester Novros and his Graphic Films studio had a major albeit little-known influence on Stanley Kubrick and 2001: A Space Odyssey. Special effects legend Douglas Trumbull worked with him in Los Angeles but ultimately moved to work directly with Kubrick in England. Barbara Miller’s article “Graphic Films and the Inception of 2001: A Space Odyssey” is good reading.

via the U.S. National Archives Youtube Channel

via the Department of Defense channel at the Internet Archive

via the National Archives and Records Administration at the Internet Archive

(links to videos 2 and 3 updated 3/22/19 following the deletion of Jeff Quitney’s Youtube Channel)