The Universe Just Got A Bit Older!

by Nicholas Mee on March 25, 2013

The universe just got a little bit older – a mere 80 million years older. More precisely, a much improved estimate of the age of the universe has just been published. Astrophysicists at the European Space Agency (ESA) have released the most accurate map of the cosmic microwave background radiation yet compiled. This is the fruit of data collected by ESA’s probe Planck. From this information it is possible to deduce that 13.82 billion years have elapsed since the origin of the universe in the Big Bang.

The Cosmic Microwave Background

The cosmic microwave background was first detected in 1964 by Arno Penzias and Robert Wilson working at Bell Labs in Holmdel, New Jersey. Penzias and Wilson were testing a sensitive new horn antenna that had been built to receive signals from Echo balloon satellites, but were plagued by interference. They were unable to eradicate or explain this background noise until a friend suggested that they look at some papers by the physicists George Gamow, Ralph Alpher and Robert Herman. In  the late 1940s Gamow and his colleagues had predicted that if the universe really had begun in the Big Bang there would be a tell-tale signal that could be detected – the universe would be filled with leftover microwave radiation that was produced shortly after the Big Bang, and this is what Penzias and Wilson had discovered.

Penzias and Wilson in front of their horn antenna.

Where Did It Come From?

The universe was created as a very hot soup of particles. As the universe expanded the temperature fell, but for the first few hundred thousand years the matter consisted mainly of a plasma of protons and electrons – the temperature was too high for atoms to form. Any electron that found itself bound to a proton in a hydrogen atom would have immediately been knocked out of the atom by violent collisions with other particles. The early universe was also filled with radiation made up of vast quantities of photons. These photons were continually scattering off the protons and electrons.

After around 380,000 years the matter had cooled to a temperature of about 3,000 degrees above absolute zero. It was now cool enough for protons and electrons to combine into hydrogen atoms. During this era the universe became transparent as the photons could no longer interact with the matter. Electrons can only occupy a discrete set of energy levels in an atom. This means that a photon can only interact with an electron in an atom if it has just the right energy to promote the electron into a higher energy level or sufficient energy to knock it out of the atom entirely. With the temperature now below 3,000 degrees the photons swarming through the universe no longer had enough energy to do this. From here on the universe has been filled with vast numbers of photons that are unable to interact with the matter that it contains.

Hot Bodies

We can tell how hot an object is by the radiation it emits. All objects give off photons and as they cool down the energy of these photons is reduced and their wavelengths becomes longer. For instance, at room temperature infra-red radiation is emitted. Infra-red cameras can pick out humans and other living creatures against background objects because they are warmer than the background and therefore emit radiation of a slightly shorter wavelength.

Our Expanding Universe

The background radiation that fills the universe last interacted with matter when the ambient temperature of the universe was around 3,000 degrees, so the radiation had the energy and wavelengths characteristic of a body of this temperature. Since then the universe has continued to expand. But it is not expanding into a pre-existing empty box. Strange as it might seem, space itself has been stretching and this has had a dramatic effect on the radiation that it contains. It means that the source of any radiation is racing away from us and the further away it is the faster it is receding.

Each cosmic microwave background photon that the Planck probe has detected last interacted with matter 13.8 billion years ago. Since this final fling with a proton or an electron the photon has sped across the universe, but throughout its epic journey the universe has grown dramatically until it is now over 1,000 times the size that it was when it was emitted. The result is an enormous stretching of the wavelength of the photon corresponding to a huge Doppler red shift. The photon is detected with a wavelength in the microwave range that is over 1,000 times as long as when it was emitted. For this reason the radiation detected by Planck has the characteristics of radiation that would be emitted by a body whose temperature is around 2.7 degrees above absolute zero, which is less than 1,000th of the original temperature.

The Planck Probe as it was being prepared for tests prior to launch.
Copyright European Space Agency.

Lumpy Cosmic Porridge

The cosmic background radiation contains a lot of information about the early universe and it is this information that cosmologists are now teasing out. For instance, some regions of the universe were slightly warmer than average and these can be detected. These regions are the places where matter had already begun to clump and would later evolve into clusters of galaxies.

The image at the top of this article shows a map of the microwave radiation detected by the Planck probe. The map shows the entire sky projected onto an ellipse. It includes radiation emitted from within our galaxy – the plane of the galaxy can be seen across the centre of the map. This radiation must be subtracted out to leave the full sky map of the cosmic microwave background. The result is the illustration shown below.

The colours in the map indicate the temperature of the cosmic microwave background across the whole sky as indicated by the wavelengths of the radiation detected by Planck. Red corresponds to slightly higher temperature. (Note: the colouring in this map is different to the colouring of the image at the top of the article.) The hotter regions are those that 13.8 billion years ago were in the process of condensing into galactic clusters.

Galactic Clusters

The Hubble Space Telescope has produced some incredible deep sky images of galactic clusters. These clusters are incredibly distant, but still much closer than the clumps detected in the microwave background. Nevertheless they give a good idea of what the clumps would eventually evolve into. In the Hubble image below each dot and smudge is a galaxy around the size of our Milky Way galaxy, home to several hundred thousand million stars and their associated planetary systems.

Distant galaxy cluster as imaged by the Hubble Space Telescope. Copyright NASA.

More Information

More detailed information about the Planck probe and what it is revealing about the universe is available on the European Space Agency website at:
http://sci.esa.int/science-e/www/area/index.cfm?fareaid=17

{ 22 comments… read them below or add one }

Gertruida March 28, 2013 at 9:30 am

as always impressive and interesting

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Alvin J Dougherty March 28, 2013 at 11:21 am

Thanks

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Aditya Thakur March 28, 2013 at 1:53 pm

Sir,
Excellent, you are enriching us.
Thank you,
Yours sincerely,
Aditya Thakur

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Chuck Ivie March 28, 2013 at 4:23 pm

How much of this “lumpiness” is intrinsic to the CBR and how much is due to the presence of intervening matter? A study of Faraday rotation and time dispersion could shed some light on this. (Pun intended)

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Ralph B. March 28, 2013 at 5:14 pm

Thank you. We need more Science. I hope that one look at the Hubble deep space image will inspire our young people to learn more and realize how insignificant our planet really is.

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J.D. Kraus March 29, 2013 at 6:04 am

What is the relationship between dark energy and negative energy?

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Nicholas Mee April 1, 2013 at 10:33 am

At the moment there isn’t even an inkling of an explanation for dark energy. I think that the name ‘dark energy’ is unfortunate because it suggests a connection with dark matter. Although we don’t yet know what dark matter is, it is just matter that is not visible, hence the name ‘dark’. The existence of dark matter is not a problem in principle and there has been no shortage of proposed solutions.
Dark energy is altogether a much deeper problem. Dark energy is ‘dark’ because it was very unexpected and it isn’t understood. It remains a complete mystery. But whatever it is, it is probably best to think of it simply as an additional unexplained force that is causing the rate of expansion of the universe to increase.

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RAC March 29, 2013 at 6:52 pm

The section “Where did it come from?” begs the very question the title asks, but sidesteps the answer, discussing only what allegedly happened AFTER the protouniverse came into existence.

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Nicholas Mee March 30, 2013 at 7:49 am

What I was asking and seeking to answer in the section “Where did it come from?” was where the Cosmic Microwave Background came from, not the much deeper and ultimate question: Where did the universe come from? If you find the answer to this one let me know.

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Wallace Wood April 5, 2013 at 9:40 am

Where the Universe came from is a little too large a question to ask using the scientific method just yet, it seems to me, of collecting and sifting data and evidence. And then coming up with plausible explanations.
You’ve done a great job of explaining the information we do have.
Non-scientifically, the ancient books of India are said to attribute the birth of universes to Brahman, who dreams up worlds beyond worlds. When Brahman awakes, it all collapses–until he sleeps and begins again.
Since we don’t have a complete explanation of our own human consciousness, we also can say we are dreaming of the creation of vast worlds. I say, “Sleep on, Great One.”

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Nicholas Mee April 5, 2013 at 4:41 pm

Very nice comment! I completely agree.

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Angelo Laudisi March 30, 2013 at 1:14 am

Thank you for explaining such a complex subject in an understandable and
interesting manner. I intend to use your presentation in my speaking engagements.

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Chuck Ivie March 30, 2013 at 7:24 pm

“Where did it come from?” is an important question but we don’t even know what it is.

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Ralph B. March 30, 2013 at 7:37 pm

My latest readings indicate that the Universe came from “nothing” through a “quantum fluctuation”. How do you visualize “nothing” and what caused the “quantum fluctuation”. Another mind boggling statement regarding the expanding Universe is that the galaxies are not speeding away on their own but the space between them is expanding. What is everything expanding into? Will we ever find the answers to these questions?

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Nicholas Mee April 1, 2013 at 10:23 am

Cosmologists have a pretty good understanding of the earliest moments of the universe. There are some glaring gaps, such as the nature of dark matter and the origin of dark energy, but overall the early universe is understood very well. However, nobody has an explanation of the birth of the universe from nothing. No-one has proposed a testable theory that explains how the universe could arise from nothing through a quantum fluctuation, and as you suggest it is not even clear what this would mean.
With regard to the expansion of the universe, distant galaxies are receding due to the expansion of space. It is not an explosion of matter within an empty box. We do not have access to any space outside the universe, so it isn’t possible for us to identify what space the universe might be expanding into. Perhaps the universe is like a gigantic balloon that is being inflated in someone’s front room. Perhaps the universe is all there is and we have to accept that in a sense new space is being created as space expands. It might not be possible even in principle to decide between these two options.

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Bob Sullivaan March 31, 2013 at 11:53 pm

Nicholas,

Is the shape displayed as an oval or oblate spheroid, of the universe correct? Why not a sphere? I ask this because, of the idea, of there being, no absolutes, or nothing existing outside of the universe.

Bob

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Nicholas Mee April 1, 2013 at 9:17 am

Dear Bob
The oval images do not represent the shape of the universe, they are maps of the entire sky (which is of course a sphere). The oval shape is due to the map projection of the information that has been gathered over the whole of the sky. It is called Mollweide’s Projection. More information is available here: http://www.progonos.com/furuti/MapProj/Dither/ProjPCyl/projPCyl.html
Best Wishes,
Nick

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Nicholas Mee April 1, 2013 at 9:18 am

Dear Bob
The oval images do not represent the shape of the universe, they are maps of the entire sky (which is of course a sphere). The oval shape is due to the map projection of the information that has been gathered over the whole of the sky. It is called Mollweide’s Projection. More information is available here: http://www.progonos.com/furuti/MapProj/Dither/ProjPCyl/projPCyl.html
Best Wishes,
Nick

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Bob Sullivaan April 3, 2013 at 11:42 pm

Nicholas,

Thanks. I understand map projections. The books I have been reading, display galaxys as disks. Are any sysems that have a spherical shape?

Thanks,
B0b

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Nicholas Mee April 5, 2013 at 4:52 pm

Dear Bob

Some galaxies are shaped like disks, as you say, but they can also be spherical or lens shaped or more irregular in shape. If you would like to find out more, take a look at the Galaxy Zoo website: http://www.galaxyzoo.org/

Best Wishes,
Nick

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Max Henner April 1, 2013 at 6:19 am

1.You are giving the age of universe 13.8 billion years, whilst previous estimate was 13.72 ie. to four valid digits. What has changed?
2.Was temperature higher than 3000K preventing formation of atoms, or just keeping their electrons away? (Plasma)
3.Is total mass of matter and energy constant since the big bang
Above all many thanks for your generous, down to Earth explanation of our complex Universe formation. It makes our life so much more engrossing.

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Nicholas Mee April 1, 2013 at 9:52 am

1. All that has changed is that the Planck probe has made more precise measurements of the wavelength of the Cosmic Microwave Background radiation over the whole sky. By analyzing the way the wavelength of the radiation varies across the sky it is possible to estimate the fundamental parameters that determine the rate at which the universe has expanded, such as the Hubble constant and the rate at which the expansion is changing. From these parameters it is possible to estimate the time that has elapsed since the Big Bang. The previous estimate of the age of the universe was derived from the measurements of NASA’s Wilkinson Microwave Anisotropy Probe (WMAP).
2. Until about 380,000 years after the Big Bang the temperature of the universe was over 3,000 degrees which was too high for atoms to form. At higher temperatures if an electron bound to a proton to form a hydrogen atom it would rapidly be knocked out of the atom by a collision with another particle or by the absorption of a photon.
3. In its earliest moments the universe would have contained equal quantities of matter and antimatter. It is assumed that there was a very small surplus of matter over antimatter (about 1 part in billion). Subsequently almost all the matter and antimatter is thought to have mutually annihilated leaving behind the small surplus of matter. This small excess of matter is what we and the rest of the universe is composed of. As yet we do not have a complete understanding of how the excess of matter came about and this is one of the main areas of research at the Large Hadron Collider. The LHCb detector is looking for matter anti-matter asymmetries in the decay of bottom quarks which are produced in abundance in the LHC. (There is of course also the dark matter whose identity is still unexplained.)

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