Monday, February 16, 2015

We live in relative time's slow motion

Colliding galaxies NGC 4038 and 4039
Professionals from several organizations, Subaru, NAOJ, NASA/ESA/Hubble and two experts on astrophotography, Federico Pelliccia and Rolf Wahl Olsen, are behind this spectacular image of two colliding galaxies.

The photo allows us to see cosmic event somse 60 million light years away in the direction of constellation Corvus. Should future astronomers take another photo in the year 5015 that is three thousand years in the future, it would look pretty much the same.

It is possible to simulate the formation and movements of colliding galaxies by writing pretty extensive computer code emulating forces of gravity and accumulation of mass in energy fields. Such simulations can then be run "in the normal speed of galaxies" instead of human experience of time measured in years. By accelerating the running of the collision simulation we can then observe in computer monitors dynamic changes caused by the cosmic accident instead of examining just a single static view, however gorgeous. The validity of the simulation code can be verified by studying other galactic crashes in the Universe showing them in different phases of the processes even each one of them we actually see only in slow motion, very slow to be more accurate.

Time is relative also to the observer. The light reaching us has travelled from the two galaxies about 60 million human years. Our timer clock uses the orbiting of Earth around Sun as basic measuring unit.

Galactic years are measured by the rotation of Milky Way around its center so that a given point, for example Sun, is back more or less where it started. This rotation has been estimated to take about 225-250 terrestrial years (wikipedia). In that time scale NGC 4038 and 4039 are at the distance of about four gyears from us. Even if the simulation runs in galactic years the collision would still be too very slow for us to follow visually as the movie would last for several years.

We live in relative time's extremely slow motion when set in the time scale of galactic years. But seeing things in that speed makes supercomputer simulated Cosmos a challenging and dynamic spectacle for laymen to admire and professionals to study in detail!

Future Milky Way Andromeda collision. Universe Sandbox

Friday, February 6, 2015

New date for earliest stars

History of the Universe
image ESO  BBC Science

Another Space theology bookmark: In an article published in BBC Science&Environment Jonathan Amos explains the background and significance of the re-dating of first stars in early Universe. The text is clear and educational for general reader and a good starting point for understanding the issue. Highly recommended!

The theological relevance of this branch of cosmology is encapsulated in the first light

Genesis 1:3

Data that changed the dating of first stars

Fossil light from early universe. Cosmic Background radiation
image ESO/Planck BBC Science

"Scientists working on Europe's Planck satellite say the first stars in the Universe lit up later than was previously thought.

The team has made the most precise map of the "oldest light" in the cosmos.

Earlier observations of this radiation had suggested that the first generation of stars burst into life about 420 million years after the Big Bang.

The new Planck data now indicates they fired up around 560 million years after the Universe got going."
J. Amos

Earliest stars through re-ionisation

Artist's impression: The first stars would have been unwieldy behemoths that burnt brief but brilliant lives
image Stanford University BBC Science
"One of these would have been imprinted when the infant cosmos underwent a major environmental change known as re-ionisation.

It is when the cooling neutral hydrogen gas that dominated the Universe in the aftermath of the Big Bang was then re-energised by the ignition of the first stars.

These hot giants would have burnt brilliant but brief lives, producing the very first heavy elements. But they would also have "fried" the neutral gas around them - ripping electrons off the hydrogen protons."

To read the entire article click here.

Sunday, February 1, 2015

Zooniverse - citizen science project

Edwin Hubble's original classification of nebulae
image W. Baade Evolution of stars and galaxies

Zooniverse is a brilliant web site representing the true essence of networking - bringing people power together to help solve questions. The site is a tool that has created a new kind of analytic tool by globally connecting thousands and thousands of human brains for observing and classifying massive amounts of scientific data.

The current Zooniverse projects include studies in six important fields of research: Space, Climate, Humanities, Nature, Biology and Physics. Everyone can participate in these real science projects from interested individuals to class rooms of students and highly trained specialists. Everyone both contributing and learning in the process.

One can hardly imagine a more exciting way to learn by doing than this - what and amazing idea!

Galaxy Zoo
Zooniverse space projects include visual examination of astronomic photos of deep space to determine shapes of galaxies in the footsteps of Edwin Hubble. A Galaxy Zoo page tells that the project began in June 2007 "with a data set made up of a million galaxies imaged by the Sloan Digital Sky Survey"
The Sloan Digital Sky Survey or SDSS is a major multi-filter imaging and spectroscopic redshift survey using a dedicated 2.5-m wide-angle optical telescope at Apache Point Observatory in New Mexico, United States. The project was named after the Alfred P. Sloan Foundation, which contributed significant funding.

Data collection began in 2000, and the final imaging data release covers over 35% of the sky, with photometric observations of around 500 million objects and spectra for more than 1 million objects. The main galaxy sample has a median redshift of z = 0.1; there are redshifts for luminous red galaxies as far as z = 0.7, and for quasars as far as z = 5; and the imaging survey has been involved in the detection of quasars beyond a redshift z = 6.
The immediate global success of the Galaxy Zoo project surprised the organizer: 70.000 galaxy classifications arrived an hour! That is significant manpower united in contributing to a single project. In summer 2008 the project had gathered about 50 million classifications from 150.000 contributors around the world. (Galaxy Zoo story).

Dealing with massive data
There is no supercomputer that is smart enough to do what human brain can do when looking at the image of a distant galaxy. There is no institution in the world that could field 200.000 volunteers to examine the Sloan photos - the logistics are overwhelming and paying for the contributions beyond the reach of Fort Knox. So we can call this a new kind of scientific tool for space exploration, analyzing visual data and spotting differences and exceptions in the data. Marvelous!
"The task in that first Galaxy Zoo was slightly simpler than yours; all we asked volunteers to do was to split the galaxies into ellipticals, mergers and spirals and - if the galaxy was spiral - to record the direction of the arms."
With such task definition it is clear that a 12 year girl in school class may see things differently from a 32 years old amateur astronomer familiar with galaxy research. But wisely the project does not filter the data with some algorithm but rather take the massive input as is with basic statistics on disagreements and agreements by various contributors:
"That meant that each galaxy was seen by many different participants. This is deliberate; having multiple independent classifications of the same object is important, as it allows us to assess how reliable our results are. For example, for projects where we may only need a few thousand galaxies but want to be sure they're all spirals before using up valuable telescope time on them, there's no problem - we can just use those that 100% of classifiers agree are spiral. For other projects, we may need to look at the properties of hundreds of thousands of galaxies, and can use those that a majority say are spiral."
Current status of Galaxy Zoo
"The present day Galaxy Zoo combines new imaging from Sloan, giving us our best ever view of the local Universe, with the most distant images yet from Hubble's CANDELS survey. The CANDELS survey makes use of the new Wide Field Camera 3 - installed during the final shuttle mission to Hubble - to take ultra-deep images of the Universe, so who knows what's out there to be found?"
Well done - and this is only one of the Zooniverse projects!