Looking at our Universe: What the Planck Results Really Mean

The Universe seems to be just as queer as we could have supposed, or maybe less queer. The results from PLANCK, which came out in their first ever press conference, 15.5 months after the probe was launched, speaks of a Universe described almost entirely by what is known to be the Standard Model of Cosmology. In other words, there is nothing that should startle us, but a lot that should be enlightening and, frankly, quite exciting.

The progress of the Universe through its ages (Courtesy: nature.com)
The progress of the Universe through its ages (Courtesy: nature.com)

For cosmology virgins, Planck is a space probe launched into an orbit around Earth designed to pick up the radio and microwave radiations from the whole Universe. By charting out the whole sky, it creates a unique map, a map of the Universe, as seen from the microwave frequency regime, and not the optical regime that we are so used to. The Universe is extremely different in these frequencies from the star-filled Universe we know and love. But these frequencies tell a different tale – one of the early universe and what imprints of that we can see today. The story of Cosmology starts right at the beginning of the Universe, or rather, more accurately 10-32 seconds after it. The Universe underwent a sudden expansion phase, called inflation, and then stabilized, while continuing to expand. The radiation from the inflationary era have got both diluted (i.e. reduced in intensity) and ‘stretched’ (i.e. their wavelengths have increased, leading to a decrease in their energy) due to the expansion of the Universe which is continuing to this very day. So ‘cold’ have these radiations become that we need specialized probes to catch them, their temperature being just 3 K (i.e. 3 Kelvin above absolute zero). The redeeming fact about these strange low-energy waves is that they are everywhere – all over the Universe. They form a kind of ‘background’ radiation and are thus called ‘Cosmic Microwave Background Radiation’ (CMBR), the name being self-explanatory.

The Universe as Planck sees it.
The Universe as Planck sees it.

The theory goes that there arose minute quantum fluctuations in the radiation soup right after the inflationary phase. As the Universe expanded, these expanded, then gravity took over and clumped matter in these pockets of disturbed equilibrium. These manifest as galaxies or clusters we see today – the tiny quantum fluctuations have grown to giant scale. The imprint of these early fluctuations will be found in the radiation seen by Planck.

The Age of the Universe

First big observation – the Universe seems to be just a bit older than we thought it to be – about 70 million years older. So the official age of the Universe become 13.82 billion years, raised from the 13.75 (or 13.77) billion it was assigned earlier.

The constituents of the Universe

It seems that the known constitution of the Universe has changed slightly from previous estimates. The matter percentage of the Universe is slightly higher than what we had known. The constitution of the Universe is mostly unknown to us and we can only put in some percentages on the amount we know and the part we are ignorant about. For example, we know that matter forms a very small percentage, followed by dark matter which forms a large chunk and that dark energy – a strange form of energy responsible for the accelerated expansion of the Universe currently – forms the largest chunk of the matter-energy pie. The earlier estimates have been bettered by Planck which quotes 4.9% ordinary matter, 26.8% dark matter and the rest 68.3% as dark energy. This is a decrease in the estimate for dark energy from previous estimates and an increase in the estimate of normal matter and dark matter. This implies that we know a bit more about the Universe (we only know about the ordinary matter part) and that the Universe is expanding at a slightly less accelerated rate than what we thought. Our ignorance about most of the Universe is only slightly abated.

The Cosmic Recipe before and after Planck results (Courtesy: ESA, Planck)
The Cosmic Recipe before and after Planck results (Courtesy: ESA, Planck)

Closely related to this is the value of the Hubble’s Constant which Planck calculates to be 67.3 +/- 1.2 km per second per megaparsec. This is a big surprise from the earlier value of the Hubble’s constant 71.0 +/- 2.5 km per second per megaparsec. The lower value of the Hubble’s constant means that the Universe is expanding slower than earlier thought.

CMB Spectrum: Cosmic Fingerprint

The whole Cosmic Microwave Spectrum as predicted by theory matches that seen by Planck to very high precision. We see the Universe at very high angular width as well as very narrow width. What Planck says is that at high multipoles, corresponding to very narrow angular width, the data matches experiment exactly. At low values of multipoles, the error bars are large, but Planck has seen as much as can be seen.

The power spectrum of the Cosmic Background Radiation and how well data fits with theory (Courtesy: Resonaances blog: http://resonaances.blogspot.in/)
The power spectrum of the Cosmic Background Radiation and how well data fits with theory (Courtesy: Resonaances blog: http://resonaances.blogspot.in/)

No probe in the future will be able to see at finer resolution, since the limit on resolution is not placed by the instrument anymore, rather by the Universe itself as a whole. Our Universe not only seems perfect, it seems good at hiding possible imperfections as well.

Asymmetry and Anisotropy

Planck gives an asymmetry in temperature over the two hemispheres of the Universe. This is a startling find, but nothing absolutely new. It’s just that Planck has confirmed – at high resolution – something that WMAP had already hinted at.

The Anomalies as seen by Planck. Notice the clear blue and red regions on opposite hemispheres. (Courtesy: ESA, Planck)
The Anomalies as seen by Planck. Notice the clear blue and red regions on opposite hemispheres. (Courtesy: ESA, Planck)

An important point to be made here: The distribution of the fluctuations are exactly random, even though we might not feel it to be so. They pass all tests of randomness. Just to emphasize, the angular distribution of the fluctuations is really exactly random. The fluctuations could have been anywhere and they just happen to be where they are! What is important is that the amplitudes of the fluctuations are not random. The amplitudes – i.e. the real temperature of the fluctuations – are not random and one hemisphere seems to be on the whole hotter than the other. This wasn’t expected! Note that a small patch of sky could’ve been warmer than the other, but this is seeing a whole trend in the temperature – one side is colder and the other hotter – and we have nothing to explain that. In fact, our cherished notions of isotropy of space (I.e. cosmological phenomena and features don’t have a preferred direction) contradict this finding. We have to wait for a verdict on this. There is also a cold spot detected in the Universe – a region of space considerably colder than the other parts. No one knows why this is the case – is it just random or is there some forces at play there?

Let’s look at a couple of more topics, both being a bit more technical.

Neutrino masses and the limit on them:

Planck puts a stern limit on the sum of the neutrino masses – a value of 0.23 eV. This is at a 95% Confidence level and this result is completely consistent with the neutrino mass being zero. However, the phenomenon of neutrino oscillation says that neutrino mass cannot be zero, no matter how small. Planck also says that the number of neutrino species is 3 and no more, well almost. This rules out those elusive sterile neutrinos, the possible fourth species of neutrinos which don’t even interact via weak interaction and their effect is felt only through the gravity that they exert.

Spectral Index and Inflationary Theories

Inflation as a theory receives a major boost from these results. The simplest inflationary models predict that knowing the two-point correlation function would be enough since the whole spectrum of the fluctuations right after inflation can be modelled by a Gaussian. Planck reinforces that. The models also say that spectrum is scale invariant (or ‘conformal’) and Planck shows slight deviation from that. A quantity called ‘spectral index’, ns, quantifies the scale invariance. If ns=1, then the scale invariance is perfect, otherwise there is deviation. Planck gives the value of ns = 0.9603 +/- 0.0073. So inflation is also nearly as simple as we can imagine and all ‘complicated’ models of inflation can be ruled out. So Planck reveals our Universe in details we have never seen before. However, even after looking at the Universe this closely, we find that the Universe is indeed plain vanilla, with a couple of chocolate chips thrown in. People are calling it the MBU or Maximally Boring Universe. Is the Universe really less queer than we thought?

[For more technical references, I refer you to the clutch of papers published by the Planck collaboration. They can be found here:
http://www.sciops.esa.int/index.php project=PLANCK&page=Planck_Published_Papers]

Indian Led Team Discovers Giant Black Holes

A team of researchers from the University of Cambridge, led by Dr Manda Banerji, has discovered previously undetected supermassive black holes in the deepest regions of the early universe. The study is published in the Monthly Notices of the Royal Astronomical Society.

Infrared colour image of ULASJ1234+0907 located 11 billion light years from Earth and one of the reddest objects in the sky. (UKIDSS / Wide-Field Infrared Survey Explorer Observatory)

A Royal Astronomical Society press release said the team used “cutting-edge infrared surveys of the sky to discover a new population of enormous, rapidly growing supermassive black holes in the early Universe”. Apparently, these black holes have been hidden from our site due to a thick layer of dust that surrounds them. One of the super massive black holes, labeled ULASJ1234+0907, is 10,000 times the size of our own Milky Way galaxy. It, and other black holes like it, is emitting enormous radiation through violent interactions with its  host galaxy.

Dr Manda Banerji said, “Most black holes of this kind are seen through the matter they drag in. As the neighboring material spirals in towards the black holes, it heats up. Astronomers are able to see this radiation and observe these systems.” He went on to say, “Although these black holes have been studied for some time, the new results indicate that some of the most massive ones may have so far been hidden from our view.”

Most of the massive black holes are located at the center of galaxies. Due to collisions with other galaxies, they are often surrounded by massive clouds of dust. The team from Cambridge used infrared surveys being carried out on the UK Infrared Telescope (UKIRT) to look past the dust and locate the giant black holes for the first time. This research could have significant impact on the way black holes are studied in the future. For more information, visit http://www.ras.org.uk.

Discovered: New Solar System that Looks Like Ours

Our solar system now has a cousin! Astrophysicists at the MIT have discovered another planetary system that resembles ours. This system is around 10000 light years away from earth.

How do you define ‘similar’? Does that mean the presence of an Earth with life? Well, not quite. Our solar system has the unique property that the orbits of its planets are nearly perfectly aligned in a plane, like lanes on a track field. This is quite in contrast with most exoplanetary systems, some of which have quite eccentric orbits. For the first time, another planetary system with perfectly aligned orbits has been discovered.

A cartoon depicting the coplanar orbits of our solar system. [Image Credit: universetoday, NASA/JPL-Caltech/T.Pyle]

Pointing Telescopes at a Star Called Kepler-30

Researchers at MIT trained their telescopes—one particular telescope, in fact, called the Kepler Telescope—on a star called Kepler-30. This star has three planets. Because the star is so far away, the only way to study it is to measure the small amount of light it radiates. They tried to determine the orbits of these planets by observing decreases in light intensity from this planet and its sunspots, which would occur when a planet transited across the observed face of the star. These sunspots themselves are moving with respect to the earth because of the star’s rotation about its axis. Thus, every time a planet transits across the star, it blocks a sunspot at a different position.

Using the timing of this data, the orbits of the 3 planets could be determined, and they were found to lie on a plane, exactly like the solar system. The orbits of the planets were also in a plane perpendicular to the star’s axis of rotation. These results were published in the journal Nature.

It’s telling me that the solar system isn’t some fluke,” says Josh Winn, an associate professor of physics at MIT and a co-author. “The fact that the sun’s rotation is lined up with the planets’ orbits, that’s probably not some freak coincidence.”

How were Systems with Non-Coplanar Orbits Formed?

This finding also backs theories on system of other planets called ‘hot Jupiters’. These are large planets with misaligned orbits around their stars. It is hypothesized that ‘planetary scattering’ led to their misaligned orbits. This theory says that these stars came close to other giant stars in the early stages of planetary system formation, and threw some planets out of the system while bringing others closer to their stars. The existence of another non-hot Jupiter system with planets far away from each other gives further credence to this hypothesis.

“We’ve been hungry for one like this, where it’s not exactly like the solar system, but at least it’s more normal, where the planets and the star are aligned with each other,” Winn says. “It’s the first case where we can say that, besides the solar system.” You can read about this research here.

First Astronomical Observatory of Harrapan Civilization Discovered

Scientists from Tata Institute of Fundamental Research (TIFR) have discovered two large circular structures which they believe were used by the Harrapan Civilization as astronomical observatories. This is a significant find as it is the first evidence of astronomy being used by the ancient people group.

Dholavira is one of the largest ancient cities of the Indus valley civilization. This civilization existed around 2650 BCE and encompassed areas of western India and modern day Pakistan. Pictured below, you can see the location of Dholavira on the map.

Courtesy Google Maps

Dholavira was first discovered in 1967 and according to Wikipedia “has been under excavation almost continuously since 1990 by the Archaeological Survey of India“. Recently, a team led by Dr. Mayank Vahia of TIFR set out to study the  Dholavira site in hopes to discover what structures might have been used as observatories.

According to an Indian Express article:

“It is highly implausible that such an intellectually advanced civilisation did not have any knowledge of positional astronomy. These (structures) would have been useful for calendrical (including time of the day, time of the night, seasons, years and possibly even longer periods) and navigational purposes apart from providing intellectual challenge to understanding the movement of the heavens,”

It is assumed that Dholavira was surrounded by water back in the day and that it was an important center of trade for the region. This idea is what drove the team to search for astro observatories due to the fact that such a cultural center had to have a strong grasp of time. Out of over a thousand structures observed so far it appears they have only been able to identify these two structures with such a purpose. Due to their “celestial orientations”, it is believed that this was their express purpose. They were able to make assumptions based on computer simulations which showed that shadows would align at an entrance on summer and winter solstice.

This study will enable scientists to measure the intelligence of the Harappan people and will give them some idea how they “used the astronomical data to conduct business, farming and other activities”.

For more information about this archaeological site see the Archaeology Survey of India’s page.


Chandra, Spitzer and VLT Find Large Galaxy Cluster From Very Early Universe

A composite image reveals a thing of utter beauty! The Chandra X-Ray Telescope, the Spitzer and the Very Large Telescope (VLT) have stitched together an image of a large Galaxy cluster that dates back right to the Early Universe, when galaxy formation was just starting to happen. The composite image is given below.

Image 1: The El Gordo Galaxy - the composite image. Blue represents the X-Rays, while the red and orange represent infrared and optical. (Courtesy: NASA/CXC/JPL/ESO)

Enter the Fat Man

Named El Gordo, Spanish for ‘fat man’, this structure appears bloated in X-Ray and infrared images. The most interesting structure is the core, which is extremely bright in X-Rays. Chandra has mapped the central part and has come up with two distinct tail-like structures, indicating that two previously large structures have merged to form the El Gordo.

The object is located in the constellation Pheonix, but this is a very difficult constellation to spot, being both very faint and extremely southerly. El Gordo is located 7.17 billion light years from Earth, which is way further than the well-known Bullet Cluster that lies about 4 billion light years away.

Stitching together to form an image

The following two images are the ones obtained by Spitzer and VLT (Image 2) and by Chandra (Image 3).

Image 2: The El Gordo in Optical and Infrared frequencies. The data has been obtained from Spitzer (IR) and VLT (Optical). (Courtesy: Optical - ESO/VLT; IR - NASA/JPL)
Image 3: The El Gordo in X-Ray. Data obtained by the Chandra X-Ray Telescope. Notice the two distinct tails and the very X-Ray hot core. (Courtesy: NASA/CXC/Rutgers/J.Hughes et al)

The composite image (Image 1) is made by combining data from the Chandra X-Ray Telescope, which gives the X-Ray data, the Spitzer telescope, which provides the infra-red (i.e. thermal) data and the Very Large Telescope (VLT), which maps the optical frequencies. The infrared and X-Rays are false coloured, with the X-Rays being represented by blue and the infrared by orange and red. The El Gordo’s central region is blue in the X-Ray, indicating that some violent X-Ray generating processes are afoot.

Dark Matter ripping out hot gases

El Gordo also shows signatures of gas which have been dispersed by dark matter, not unlike the Bullet cluster. Dark matter has not been stopped by collision, due to feeble interactions with the mass outside, but the hot gas has been. Dark matter has then ripped apart the hot gas and this forms the halo, which is incandescent in both Optical and X-ray frequencies, and presumably even in Radio. In fact, the X-Ray emitting hot gas, forming the halo-like structure around El Gordo, account for more than 90% of the visible mass of the galaxy cluster as compared to just about 1-3% contribution from actual stars. The number of stars is, however, massive – there are about 4 quadrillion (a million billion) of them!

Sixty Symbols Educates You Through the Power of YouTube

The good folks at the University of Nottingham have put together sixty videos on a variety of topics, aiming to educate you (the young learner with a rapt internet-induced attention deficit), on some of the most mind boggling facts and facets of our science.

In other words, we live in a very very strange universe filled with squiggly diagrams and improbability that approaches Douglas Adams’ metaphorical science fiction escapades. Everything from Schrödinger’s Cat, infinity, vuvuzelas, quantum tunneling and Feynman’s squiggly diagrams have been put up in a mysterious-looking site.


Each video has an assortment of nerdy scientists explaining each phenomenon in the most non-confusing way possible (which is a paradox in itself, because trust me nothing is crazier than quantum physics. Nothing). The scientists, however, have done quite a marvelous job at explaining these concepts fairly well, and the project page itself is quite friendly:-

Ever been confused by all the letters and squiggles used by scientists?

Hopefully this site will unravel some of those mysteries.

Sixty Symbols is a collection of videos about physics and astronomy presented by experts from The University of Nottingham.

They aren’t lessons or lectures – and this site has never tried to be an online reference book.

The films are just fun chats with men and women who love their subject and know a lot about it!

Head over to SixtySymbols to get your science fix for the day! (via ReadWriteWeb)

Experience Longest Solar Eclipse on 15th January, 2010

A solar eclipse occurs when the Moon comes directly between the Sun and the Earth, producing a shadow on the Earth’s surface where the Sun is completely or partially obscured. Solar eclipses are rare because the moon seldom comes in the direct path between the Earth and the Sun.

The solar eclipse of 15th January, 2010 will be the century’s longest eclipse, having a totality duration of 11 minutes, 8 seconds (visible in India for 10 minutes, 24 seconds). It starts at 10:44 AM IST (5:14 AM GMT) and ends at 2:29 PM IST (8:59 AM GMT). This is an annular eclipse, that is the apparent diameter of the Moon is slightly smaller than the apparent size of the Sun. Thus at totality (when the entire disc of the Moon covers the Sun), the Sun forms a bright ring (or annulus, hence the name) around the Moon.

The eclipse can be best seen in India in the town of Dhanushkodi at the southern tip of Rameshwaram. It is reachable by fish boats or 4×4 SUVs.

Here is how the eclipse will look at totality near Dhanushkodi:


Following this are the scenes of maxima in the major cities of India:






Word of warning: Do NOT stare at the eclipse (or the Sun, for that matter) with naked eyes or through run-of-the-mill sunglasses. Your eyes will be put at risk. An even louder word of warning: do NOT look at the eclipse with unshielded binoculars or telescopes. You will definitely burn your eyes if you do that. Please wear adequate protection. Specially designed solar eclipse goggles are available which will protect your eyes from the brightness of the Sun.