Tag: The Big Bang

Arno A. Penzias, co-discoverer of the Cosmic Microwave Background (CMB), the first evidence for the Big Bang has died at the age of 90.

Most people I suppose have never heard of Arno A. Penzias, but everyone has heard of the Big Bang Theory, the idea that about 14 billion years ago, give or take a couple hundred million, the entire Universe underwent an unimaginable explosion and the expansion caused by that explosion continues today. Well it was Doctor Penzias, along with his colleague Robert W. Wilson who provided the first actual evidence that the Big Bang really happened.

Robert W. Wilson, left, and Arno Penzias, Bell Lab employees who won the 1978 Nobel Prize in physics, are shown standing in front of their microwave antenna at Bell Labs in Holmdel, N.J., Oct. 17, 1978. (AP Photo)

The story of Doctor Penzias contains within it several of the themes that often occur in both science and human history at large. Arno Penzias was born in 1933 in Munich, Germany to Jewish parents. If you can imagine a worse place and time for a Jewish boy to enter the world, well I can’t. Arno was lucky however for he and his brother were part of a British program that brought 10,000 Jewish children out of Nazi Germany just before World War 2 began. Later Arno’s parents also succeeded in escaping Germany and the whole family arrived in America in 1940. Arno was therefore one of the very large number of talented scientists who came to America and who made their discoveries here after fleeing Nazi tyranny.

From Left, Neils Bohr, James Franck, Albert Einstein and Isidor Rabi. Four Nobel Physicists who came to America to escape persecution in Europe. Actually Rabi’s parents fled to America, he was born here but you get the idea! (Credit: Arkiv.org)

Interested in science from an early age Arno first intended to become a chemist but switched majors to Physics while attending the City College of New York. Arno would eventually receive his Ph.D. in 1962. Even before becoming a Doctor however, in 1961 Arno accepted a job on the project that would lead to his greatest discovery.

After WW2 the GI Bill and a booming economy allowed a huge increase in the number of young Americans who attended college. (Credit: Old Magazine Articles)

In the early 1960s Bell Labs in Holmdel, New Jersey was one of the centers for ‘space age’ technology. The transistor had been invented there, as had the Laser. Communications satellites were the next big thing and indeed Telstar; the first communications satellite was built at Bell Labs. The engineers who were designing Telstar needed to know, once their satellite was up in orbit, what kind of radio sources there were in the Universe at large that could cause static interference with Telstar.

Bell Labs in Holmdel N.J. circa 1060 when Arno Penzias would have started working there. (Credit: Reddit)

That was the job that Arno Penzias and his colleague Robert Wilson were assigned, survey the entire sky at microwave frequencies and catalogue all of the radio sources that could cause problems for communications satellites. To accomplish their task Penzias and Wilson used the brand new Holmdel Horn antenna, especially designed for communicating with satellites and at the time one of the largest radio antennas on Earth. With such a powerful instrument in their hands the two physicists were determined to not just survey and catalogue radio sources, but to study them as well.

In the early days of Radio Astronomy measurements were used to develop contour maps of radio sources like this one of the center of the Milky Way. (Credit: ResearchGate)

As the two men carried out their survey they quickly ran up against an annoying, so they thought, little problem. No matter where they pointed their antenna, no matter when, there was always a persistent background hiss that they couldn’t get rid of. The hiss didn’t come from any source, it was everywhere, so they initially thought it had to be man made noise from something nearby. Working methodically the two men eliminated radar from nearby airports as the cause, noise from many sources coming from nearby New York City even the possibility of radiation from nuclear tests. One of their efforts to eliminate the noise has become something of a anecdote in physics departments. Noticing that several pigeons were nesting inside the big horn antenna they wondered if the bird’s droppings could be the cause of the hiss so they gave the entire horn a through clean out. No good, the noise remained.

In our modern world there are all sorts of things, both natural and man-made, that can generate radio noise that will interfere with communications. (Credit: IQS Directory)

Looking through the literature for some idea as to what could be going on they came across a paper written by physicists George Gamow and Ralph Alpher about how the Big Bang, if it had actually happened, should have left behind a measurable amount of heat, the way a frying pan on your stove stays warm for a while after you turn off the burner. After billions of years Gamow and Alpher calculated that residual heat would now be observable in the microwave region, just where Penzias and Wilson’s hiss was. (For more information on George Gamow and the prediction of the CMB see my post of 30 October 2021.)

The first prediction of a Cosmic Microwave Background (CMB) in the November 1948 issue of the journal Nature. (Credit: TheCuriousAstronomer)

Since Gamow and Alpher were teaching in Colorado and Texas respectively Penzias and Wilson decided to contact physicist Robert Dicke at nearby Princeton University. In another of those coincidences that no one could ever imagine Dicke and his students were actually planning on looking for the CMB and were gathering up the equipment they’d need to look for it. As remembered by Nobel Prize winner James Peebles, a graduate student of Dicke’s at that time he was in his mentor’s office when the call came from Wilson. “We’ve been scooped!” Dicke said as he put down the phone.

From right, Robert Dicke, Jim Peebles along with physicist David Wilkinson in their lab at Princeton University. (Credit: Nobel Prize)

That was in 1964 and the news of the discovery of the CMB spread quickly turning the subject of cosmology from a few people working on a few ideas to a major study on which thousands of researchers around the world are working. Penzias and Wilson were awarded with the 1978 Nobel Prize for their discovery. The moral of this story is to keep alert, if some unknown factor is effecting your measurements don’t just ignore it, find out what it is. Like Rontgen and the discovery of X-rays, sometimes that unknown factor is more important than the thing you started out trying to study. In both cases the scientists became famous for discovering something they never even planned on looking for.

Penzias and Wilson saw the CMB as a constant everywhere they looked but today’s measurements, from the Planck satellite, show a very small variation in the temperature. These variations form the seeds out of which today’s galaxies and stars would form. (Credit: New Scientist)

Arno A. Penzias died on the 22nd of January at an assisted living facility in San Francisco. His death was due to complications from Alzheimer’s disease. There were a huge number of major scientific discoveries made during the 20th Century; Arno A. Penzias’ discovery that ‘the Universe began, not with a whimper but with Bang’ may have been the biggest.  

New Astrophysics Study proposes another process by which the heaviest elements, such as Gold can be created by Black Holes.

Back in High School we all learned that the objects in our daily life here on Earth are made up of a large number of chemical elements such as oxygen or carbon or iron. We also learned that all of those elements, no matter how different, were themselves made up of only three types of sub-atomic particles the electron, the proton and the neutron. By the way those protons and neutrons are themselves made up of even smaller particles called quarks. At the present time that’s as far down as it goes.

The Periodic Table of the elements, more than 100 different substances, with many different properties, all made from just different combinations of Protons, Neutron and Electrons. (Credit: PubChem)

Now a trillionth of a second after the big bang the Universe was a seething mass of all of the elementary particles that make up what physicists call ‘The Standard Model’. As the Universe expanded and cooled however the quarks combined to form the protons and neutrons. All that took place within the first second after the big bang.

The Standard Model of elementary particles. Physicists think that there is some underlying simplicity beneath this model, like Protons, Neutrons and Electrons for the periodic table, but we haven’t figured it out yet. (Credit: Dreamstime.com)

After that most of the protons just stayed protons becoming hydrogen nuclei so that hydrogen, the simplest element is still the most abundant of all the elements. Later, we think about 2 minutes after the big bang some of the protons and neutrons came together to form helium nuclei. A million years later, as the first stars began to form those were really the only two elements that existed. Before the first stars formed the visible matter in the Universe was about 75% hydrogen and 25% helium by mass. Virtually none of the other elements, like sodium, calcium or copper, were created in the Big Bang.

Our Universe’s baby picture, the Cosmic Microwave Background (CMB). At this point the only chemical elements that existed were Hydrogen and Helium. Where did the rest come from? (Credit: Wikipedia)

So where did all of those elements come from, where did the carbon, oxygen and nitrogen that make up your body come from. Those elements, and many others were made inside of those first stars; they were generated by the fusion reactions that gave energy to those suns. Beginning with fusing hydrogen into helium as a star starts to run out of hydrogen its core becomes hotter and denser so that it begins to fuse helium into carbon and oxygen and then it will fuse carbon and oxygen to make the elements up to iron.

When a star, such as our Sun, reaches the end of its lifetime and is running out of both hydrogen and helium for fuel it starts to expel a large portion of its mass as a planetary nebula like the famous Ring Nebula shown here. This is how the Universe gets most of it’s Oxygen, Nitrogen, Carbon and other light elements up to Iron. (Credit: Sky and Telescope)

Iron is a dead end however because you can’t get any more energy by fusing iron so the star’s core can no longer fight the force of gravity and begins to collapse while the outer regions explode as a massive supernova. In that titanic detonation enough energy is released to produce some of the heavier elements such as silver, tin or iodine. Even so those elements are far less common in the Universe than are elements lighter than iron like carbon and oxygen.

The Crab Nebula is the remenants of a supernova explosion. There’s a lot of the lighter elements here but also a small amount of the heavier elements. (Credit: Wikipedia)

Then there are the heaviest elements of them all, elements like gold or lead or uranium. While a tiny amount of these substances may be created in supernovas astrophysicists now think that much of the heaviest atomic nuclei are produced in an even rarer cosmic event than a supernova, the merger of two neutron stars. This hypothesis is gaining favour thanks to the data obtained by gravity wave detectors like the Ligo experiment that have actually observed neutron star mergers.

With our new Gravity Wave Observatories astronomers can now study the mergers of two neutron stars. Theoretical studies indicate this is another source for even the heaviest elements. (Credit: Forbes)

Now a research group at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt Germany, in cooperation with scientists in Belgium and Japan have conducted computer simulations showing how even the heaviest elements could also be produced in the accretion disks that form around black holes. According to Doctor Oliver Just, an astrophysicist and member of the group, “In our study, we systematically investigated for the first time the conversion rates of neutrons and protons for a large number of disk configurations by means of elaborate computer simulations and we found that the disks are very rich in neutrons as long as certain conditions are met.” Which is a fancy way of saying the heaviest chemical elements could be produced in a black hole’s accretion disk.

First ever image of a Black Hole taken by the Event Horizon Telescope. What you’re actually seeing here is the accretion disk around the Black Hole itself. A new study proposes that the accretion disk of Black Holes may be a source for heavy elements. (Credit: Wikipedia)

As matter is drawn into the black hole from the accretion disk the release of energy is so great that some matter escapes before it enters the black hole. This escaping matter could therefore produce a small but constant output of heavy elements.

As matter is pulled into the Black Hole from its accretion disk so much energy is released that a small amount escapes from the polar regions at relativistic speeds. (Credit: Space.com)

At the moment this is just a hypothetical simulation but certainly the accretion disk of a black hole is a location where there is enough energy being released to produce even the heaviest elements. More data from observations of accretion disks is needed so that the group can refine their simulations and fortunately that data is now becoming available thanks to the work of the Event Horizon Telescope,the astronomers who two years ago released the first actual picture of a black hole. See my post of 17 April 2019.

Signals from radio telescopes around the world were combined to produce a single telescope thousands of kilometers in diameter. This ‘Event Horizon Telescope’ took the first ever image of a Black Hole. (Credit: www.ru.nl)

Where the chemical elements came from is a question that scientists have asked since the idea of atoms and elements was first suggested. Today we know a great deal, but there’s still much more to learn.