Neil deGrasse Tyson's Dark Matter Movie Notes from Hayden Planetarium

December 28, 2015

Saw Neil deGrasse Tyson's Dark Matter Movie at  Hayden Planetarium yesterday.  Here are some notes I jotted down while watching the film to save you a trip.  You're welcome.

13.8 billion years ago, the Big Bang (derisively named by its detractors) started emitting energy and matter. 

Mount Wilson in the 1920s was the largest telescope in the world at the time.  Andromeda was a pulsating star.  By studying it carefully, Edwin Hubble was able to figure out that it was much brighter than our sun and much farther away than the edge of our galaxy.  By studying its red shift and that of thousands of other galaxies, he was able to determine that the galaxy was expanding.  

Andromeda is over 2 million light years away, so we see it now as it was 2 million years ago, long before humans walked the earth. 

Light from the farthest galaxies started out billions of years ago. 

No matter where you are in the universe, you seem to be the center of it with everything expanding out away from you at an ever increasing rate (things farthest away are moving away from you faster than things that are closer).

The universe used to expand at a greater rate than it does today, the opposite of what was once thought theoretically before it was carefully measured empirically.    Its rate of expansion seems to have been accelerating for at least the last 5 billion years or so. 

The universe is cool (only 3 degrees Kelvin on average) and getting cooler as it expands.  At the time of the Big Bang it was hotter than the sun is today. 

In 1964 at Bell laboratory in New Jersey, microwave radiation from the Big Bang was first recognized as cosmic background radiation.  Mapping it allows us to know the distribution of matter and energy.  Blue areas are more dense and where galaxies form.  Red areas are enormous voids.   The cosmic background radiation marks the visible edge of the known universe. 

In 1995, the Galileo space shot released a probe that parachuted down into the atmosphere of Jupiter to measure the amount of heavy hydrogen in this enormous "cold storage locker" that trapped and preserved elements from a time much closer to the Big Bang, 4 billion years ago.   The amount found was consistent with predictions made by those positing a Big Bang. 

Most matter is not made of matter at all but of dark matter which must account for the additional mass necessary to hold galaxies together (the observed matter doesn't suffice).  It's thought that galaxy clusters are held together by a network of dark matter. 

Trillions of stars in a galaxy distort the gravity around it, but the distortion is greater than the observed matter. 

Supernovas massive explosions resulting from two colliding ghosts of old stars.  They occur at a rate of about 2 per century per galaxy. 

Matter and energy are the same, interchangeable per Einstein's e = mc². 

The universe appears to be about 70% dark energy with dark matter making up the bulk of everything else. 

Normal matter is only 5% of the universe. 

The universe must be bigger than the part we can see (the part whose light has reached us already).  Some believe it's infinitely large, others that it is perhaps 4 or 5 times as large as the visible universe (the part we can see).