October 9, 2019 —
During the press conference in which he was revealed as one of the winners of the 2019 Nobel Prize in Physics, James (Jim) Peebles was asked to point to a single discovery or breakthrough from his long career that would put the award in context. Peebles demurred, replying instead: “It’s a life’s work.”
That’s a perfect description of his contribution to our understanding of the universe. His is a career so influential that he is widely recognised as one of the key architects of the field of physical cosmology, the study of the universe’s origin, structure and evolution. I am sure I am not alone in regarding Peebles as the greatest living cosmologist.
Peebles’s research career started in the early 1960s. The Canadian-born scientist earned his undergrad at the University of Manitoba and later gained his PhD in the group of Robert Dicke at Princeton University in New Jersey in 1962. He has remained there ever since. Peebles now holds the title of Albert Einstein Professor of Science at Princeton.
In the 1960s, Dicke’s group was working on theoretical predictions – and the corresponding observational consequences – for the state of the “primordial” universe, the phase immediately following the Big Bang lasting for a few hundred thousand years. At that time the Big Bang theory for the formation of the universe was not yet fully accepted, despite observational evidence that galaxies were moving away from each other.
Dicke’s group was working on the theory that if the universe was expanding, then it must have been much smaller, hotter and denser in the past. The prediction was that the thermal radiation from this epoch might be still be observable today as background radiation pervading the universe. The Princeton group was also designing instruments to try to detect it.
Meanwhile, Arno Penzias and Robert Wilson, working for Bell Labs (also in New Jersey), had detected an unusual persistent background noise in their experiment. They were investigating the use of high altitude “echo” balloons, a kind of early satellite communication.
When Penzias and Wilson approached Dicke’s group for advice, it became clear that they had actually detected the relic background radiation. We call it the cosmic microwave background (CMB) because the radiation peaks in the microwave part of the electromagnetic spectrum.
The resulting papers were arguably the birth of the field of observational cosmology, a branch of physics that has revolutionised our view of the cosmos and our place within it. Peebles played a pivotal role in our theoretical understanding of the primordial universe and its evolution, but he also recognised that the CMB was a treasure trove of information that could be plundered. In particular, it holds clues about the formation of cosmic structures – the galaxies – and indeed clues about the fundamental nature of the universe itself.
Much of Peebles’s work has focused on understanding the emergence and growth of structure in the universe from the relatively smooth primordial conditions encoded in the CMB. In the process he has helped define an entire field of study.
For example, in the early 1970s, he was one of the first to run computer simulations of cosmic structure formation, a practice that is an entire branch of research today, where cosmologists explore toy universes.
Peebles helped usher in the “dark sector” to our model of the universe, becoming a pioneer of (what is now called) the standard cosmological model. In this model, the universe is dominated by mysterious forms of matter and energy that we are yet to fully understand, but whose existence is supported by observational evidence. Normal matter now has an almost negligible cosmic relevance compared to this dark matter and dark energy.
Peebles has produced such an immense body of work it is impossible to do it all justice in this short article. In one of his most influential papers, he linked the subtle fluctuations in the temperature of the CMB – which reflect ripples in the density of matter shortly after the Big Bang – with the way in which matter is distributed on a large-scale throughout the present day universe. The link exists because all the structure we see around us today must have grown through the evolution of those primordial seeds.
Peebles advanced the concept of a dark matter component to the universe and its implications for the evolution of structure. Through this, and other work, he helped establish the theoretical framework for our picture of how galaxies have formed and evolved. And he demonstrated how observations of the CMB and the distribution of galaxies could be used as evidence to help measure key cosmological parameters, the numbers that feature in the equations we use to describe the nature of the universe.
The influence of Peebles doesn’t end there. Aside from his monumental contributions to fundamental research, spanning the CMB, dark matter, dark energy, inflation, nucleosynthesis, structure formation and galaxy evolution, his textbooks have educated generations of cosmologists. They will do for years to come. His Principles of Physical Cosmology is on my desk right now.
In the Nobel press conference, Peebles was keen to highlight that he didn’t work alone. But to say that he has been largely responsible for shaping our understanding of the universe is a cosmic understatement.
This story from James Geach was originally published by The Conversation.
Interstellar visitor is reddish, new study finds – CBC.ca
In a new study published in Nature Astronomy on Monday, astronomers are pulling back the curtain on some of the mysteries behind our solar system’s first confirmed interstellar comet.
The comet, 2I/Borisov, was discovered by amateur astronomer Gennady Borisov on Aug. 30, though its orbit was unknown.
But by the end of September, the International Astronomical Union’s Minor Planet Center confirmed that the comet came from beyond our solar system.
Because Borisov is so distant — 420 million kilometres from Earth — it’s difficult to determine a lot of its characteristics. However, this new study, the astronomers were able to determine a few of its interesting qualities.
Using two telescopes, the Gemini North Telescope in Mauna Kea, Hawaii, and the William Herschel Telescope in La Palma, Spain, they were able to determine that the nucleus, or core, is roughly one kilometre in diameter.
They also identified a short tail and an extended coma, or cloud of debris that gives comets their fuzzy appearance. And they determined its colour.
“We found this colour of the comet is almost the same as other colour of the typical comets in our solar system,” said co-author of the paper Piotr Guzik, an astronomer at the Astronomical Observatory at Jagiellonian University in Krakow, Poland. “It’s not red like Mars … it’s just a bit more red light in its spectrum than the blue light.”
In another study, researchers also found that Borisov contained cyanogen, which is made up of a carbon atom and a nitrogen atom that are bonded. It is a poisonous gas to us, but commonly found in comets.
Second interstellar visitor
Borisov is the second known object to come from another star system.
While ‘Oumuamua was detected on its way out of the solar system, Borisov was detected on its way in, which means astronomers will be able to study this one for some time.
“The next year is going to be extremely exciting, as we will be able to follow 2I’s evolution as it zooms through our solar system,” said Olivier Hainaut, an astronomer at the European Southern Observatory, in a statement. “In comparison, we had only a few weeks to study ‘Oumuamua before it became too faint.”
So far, the Borisov findings suggest it isn’t very different from our own local comets, something that Guzik believes could shed light on exoplanets, which orbit other stars.
“Such objects are just part of other planetary systems. It was not until, I guess, around 1990 that we found the first planet systems around other stars, and now part of such a system is here,” Guzik said. “So we can investigate some material that left some planetary system and compare it to what we see here and probably learn something about the formation of other planetary systems.”
Though the recent study found cyanogen, Guzik said that he’s hopeful that, as the comet gets nearer the sun, astronomers will discover more about its composition.
“It will be very interesting to find out more, especially what’s driving its activity,” he said.
Borisov will reach perihelion — its closest approach to the sun — on Dec. 7, when it will be roughly 300 million kilometres away.
Guzik also hopes that, eventually, astronomers will be able to determine its home star system.
“It would be really nice to know where it originated,” Guzik said. “If we could point to the star and say, ‘This is the star.'”
Asteroid news: Did alien space rock dust cloud spark new life on Earth? – Express.co.uk
Scientists have now posited an asteroid disintegration once blanketed Earth with dust millions of years ago. It is thought the cosmic event dramatically cooled Earth, triggering an ice age followed by significant increases of new animals. The work, led by Professor Birger Schmitz of Sweden’s Lund University, provides new insight into the impact of extraterrestrial events on Earth’s evolution.
The asteroid expert told the Observer: “We know about the 6 mile (10km) asteroid that crashed on Earth 67 million years ago and killed off the dinosaurs, but this event was very different.
“It occurred about 470 million years ago when an asteroid 3,000 times bigger than the dinosaur-killer was destroyed during a collision with another asteroid beyond the orbit of Mars.
“It filled the solar system with dust and caused a major dimming of sunlight falling on Earth.”
The theory is a reduction in radiation made the planet’s temperatures drop significantly.
This triggered a succession of ice ages, meaning water froze, ice caps spread and sea levels dropped.
This created isolated shallow seas which were an ideal breeding ground for generating new species.
Cold water also holds more dissolved oxygen, which would also have boosted speciation.
Scientists are already aware ice ages appeared around this time and life underwent a spike in biodiversity, particularly in the oceans.
The first coral reefs began to grow then and peculiar tentacled predators called nautiloids first appeared.
This is called as the great Ordovician bio-diversification event (GOBE).
Scientists have argued over GOBE’s cause but now Professor Schmitz, who studying space dust particles in seabed sediments, believes it was triggered by asteroid dust clouds.
He said: “The sediments laid down at this time are rich in the isotope helium-3 – which they could only have picked up travelling through space. It is a crucial clue.”
READ MORE: NASA chief reveals nuclear ‘game changer’
Professor Rebecca Freeman, of the University of Kentucky, told Science how she agreed with the idea.
She said: “Other scientists have backed his idea. “It isn’t necessarily the answer to every question we have about GOBE, but it certainly ties together a lot of observations.”
Professor Schmitz’s research has also caused interest for another reason.
As the world warms dangerously, some scientists have proposed spreading a veil of dust hovering in space over the Earth, reflecting sunlight away from our overheating planet.
But the idea is controversial with critics because it could have unexpected side-effects.
Now evidence shows such an experiment occurred naturally 470 million years ago.
The result was a major change in our meteorology and the evolution of life here.
Professor Schmitz added: “It is certainly worth bearing in my mind in coming years.”
Alien life possibly found on Mars in 1970s, ex-NASA scientist says – Fox News
In the article, Gilbert Levin, who worked on the Viking missions to the Red Planet during that decade, makes it clear that he believes data from the Labeled Release (LR) in 1976 was supportive of finding life.
“On July 30, 1976, the LR returned its initial results from Mars,” Levin wrote in the op-ed, entitled “I’m Convinced We Found Evidence of Life on Mars in the 1970s.”
“Amazingly, they were positive. As the experiment progressed, a total of four positive results, supported by five varied controls, streamed down from the twin Viking spacecraft landed some 4,000 miles apart.”
He continued: “The data curves signaled the detection of microbial respiration on the Red Planet. The curves from Mars were similar to those produced by LR tests of soils on Earth. It seemed we had answered that ultimate question.”
The LR, which was led by Levin, took samples of Martian soil that contained organic compounds and looked for carbon dioxide. Astonishingly, the results seemed to indicate that the carbon dioxide was “being regenerated, possibly by microorganisms as on Earth.”
Fox News has reached out to NASA for comment for this story.
However, Levin seemed to criticize the space agency for not following up on the LR findings, even if NASA concluded that it “found a substance mimicking life, but not life.”
“Inexplicably, over the 43 years since Viking, none of NASA’s subsequent Mars landers has carried a life detection instrument to follow up on these exciting results,” he continued. “Instead the agency launched a series of missions to Mars to determine whether there was ever a habitat suitable for life and, if so, eventually to bring samples to Earth for biological examination.”
NASA has made subsequent visits to Mars, including the InSight lander, which landed in November 2018. The Curiosity rover, which has been on Mars since August 2012, detected a surprising spike in the level of methane that it has not yet been able to explain.
Last November, NASA announced that it had picked a landing spot for its upcoming Mars 2020 mission, a rover that will not include “a life-detection test,” Levin wrote.
“With our current measurements, we have no way of telling if the methane source is biology or geology, or even ancient or modern,” said SAM Principal Investigator Paul Mahaffy of NASA’s Goddard Spaceflight Center in a June statement. On Earth, methane is produced both biologically and geologically.
Levin pleaded for the space agency to put “life detection experiments on the next Mars mission possible” to be more precise in their hunt for life, but in also keeping “with well-established scientific protocol.” He also wants an independent group of scientists to review the Viking LR data.
“Such an objective jury might conclude, as I did, that the Viking LR did find life,” Levin concluded. “In any event, the study would likely produce important guidance for NASA’s pursuit of its holy grail.”
The newly published op-ed is not the first time Levin has suggested that life was found on Mars. In 1997, he published “his conclusion that the LR had, indeed, discovered living microorganisms on the Red Planet,” according to his website.
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