This Is Why ‘Physical Cosmology’ Was Long Overdue For The 2019 Nobel Prize
“It is a spectacular fact of modern science that the predictions of theoretical cosmology have been verified and validated by ever-improving observations and measurements. Even more remarkably, when we examine the full suite of the cosmic data humanity has ever collected, one single picture accurately describes every observation together: a 13.8 billion year old Universe that began with the end of cosmic inflation, resulting in a Big Bang, where the Universe is comprised of 68% dark energy, 27% dark matter, 4.9% normal matter, 0.1% neutrinos, and a tiny bit of radiation with no spatial curvature at all.
Put those ingredients into your theoretical Universe with the right laws of physics and enough computational power, and you’ll obtain the vast, rich, expanding and evolving Universe we have today. What was initially an endeavor of just a handful of people has now become the modern precision science of cosmology. In the middle of the 20th century, legendary physics curmudgeon Lev Landau famously said, “Cosmologists are often in error but seldom in doubt.” With the 2019 Nobel Prize in Physics going to Jim Peebles, perhaps the world will recognize it’s long past time to retire Landau’s quote. We may live in a dark Universe, but the science of physical cosmology has shed a light on it like nothing else.”
I see you out there. You, the person who’s skeptical of dark matter. You, the one who thinks dark energy must be an enormous cosmological mistake. You, who thinks the Big Bang is a hoax and that inflation is a band-aid for a failing theory. And you, especially you, the one who derides cosmology as a pseudoscience, quoting Landau like his more-than-60-year-old quote is still relevant.
Physical cosmology is a real, robust science. It’s not only my field, but my grand-advisor, Jim Peebles, won the 2019 Nobel Prize for his work pioneering it. Come learn what all the fuss is really about.
This Is The One Way The Moon Outshines Our Sun
“Unlike the Sun, the Moon’s surface is made of mostly heavier elements, while the Sun is mostly hydrogen and helium. When cosmic rays (high-energy particles) from throughout the Universe collide with heavy atoms, nuclear recoil causes gamma-ray emission. With no atmosphere or magnetic field, and a lithosphere rich in heavy elements, cosmic rays produce gamma-rays upon impacting the Moon.”
When you view the Moon with your eyes, you’re not seeing it shine so brightly because it’s emitting its own light. Rather, it’s reflecting sunlight on its illuminated phase and reflecting light emitted from Earth (known as “Earthshine”) on the darkened portion. If you look at the Moon in many different wavelengths, from radio to infrared to ultraviolet to X-ray energies, you’ll find that the Sun is much brighter, and the Moon primarily emits light due to reflection.
But in gamma-rays, that entire story changes. The Sun emits virtually no high-energy gamma-rays, with only minor bursts during solar flared. The Moon, on the other hand, emits high-energy gamma-rays constantly; for almost 30 years we know that it outshines the Sun in this particular wavelength range.
It might sound puzzling to you, but there’s a good physics reason for this, and a fun little science fact that everyone should appreciate. Get the story today!
Again and again the principle of least action catches me – it’s too damn beautiful.
Starts With a Bang podcast #49: The LHC and the future of physics
The Large Hadron Collider, located at CERN, is the most powerful particle accelerator and collider in human history, and the detectors that observe the collisional debris are the most sensitive and comprehensive ever constructed. With this powerful new tools, physicists discovered the Higgs boson earlier this decade, and continue to probe the frontiers of the known Universe.
Currently undergoing upgrades, the LHC has only collected, to date, 2% of the eventual data it will wind up collecting. Meanwhile, physicists are already planning for the future, looking to build a next-generation collider capable of probing the frontiers beyond the LHC’s reach.
Yet many detractors, dissatisfied with the motivations for pushing these boundaries forward, are working to obstruct this tremendous, civilization-scale endeavor. My guest this month on the Starts With A Bang podcast is Dr. James Beacham, a scientist who works as a member of CERN’s ATLAS collaboration. In a far-ranging discussion, we talk about the LHC and beyond as we face an uncertain but potential-filled future for particle physics. This is one discussion you won’t want to miss!
(Image credit: CERN / Maximilien Brice and Julien Marius Ordan)
Ask Ethan: How Dense Is A Black Hole?
“I have read that stellar-mass black holes are enormously dense, if you consider the volume of the black hole to be that space which is delineated by the event horizon, but that super-massive black holes are actually much less dense than even our own oceans. I understand that a black hole represents the greatest amount of entropy that can be squeezed into [any] region of space expressed… [so what happens to the density and entropy of two black holes when they merge]?”
The entropy of a black hole, if you simply applied the laws of General Relativity (and nothing else), would simply turn out to be zero. By giving it a quantum description, however, we can get a meaningful formula for entropy: the Bekenstein-Hawking equation. When two black holes merge, the entropy is greater than even the pre-existing entropies combined.
If you think that’s weird, you might suspect that your instinct for density would also be incorrect. Sure, density is just mass divided by volume, but which volume do we use for a black hole? The volume of the event horizon? The volume of a (volume-less) singularity? Something else?
The question of how dense a black hole is has a lot of potential pitfalls, but if we follow the physics closely, we can answer it. Here’s how it’s done.
Physics, Not Genetics, Explains Why Flamingos Stand On One Leg
“Compared to a flamingo in the water that stands on one leg, an identical flamingo with two legs in the water will lose somewhere between 140-170% the total body heat that the flamingo on one leg loses. That means the flamingo that does learn the preferred behavior — standing on one leg — is free to spend more time in the water: more time feeding, grooming itself, scouting the waters, etc.
In short, a flamingo that learns to stand on one leg will have more chances for evolutionary success and survival than one that stands on two legs. The flamingos may not be smart enough to know that it’s important to stand on one leg in the water but not so much in the air; instead, it appears to be a behavior that flamingos engage in regardless of their environment. And, as far as scientists can tell, there’s no gene for standing on one leg; rather, it’s a behavior that gets passed down from a mother flamingo to her offspring as she raises them.”
Flamingos are pretty weird birds. They have unusually long and skinny legs and necks; their beaks are inverted from most birds; their mating dances only occur in enormous groups; and they range in color from a pale white to a deep pink, orange, or even red. But the defining property of a flamingo, at least to most humans, is that they stand on one leg.
Why would it benefit a flamingo to stand on one unstable leg, rather than two stable ones? Physics, not genetics, explains this flamingo behavior. Come understand the reason today.
Did Our Universe’s Structure Grow From The Top-Down Or From The Bottom-Up?
“A century ago, we didn’t even know what our Universe looked like. We didn’t know where it came from, whether or when it began, how old it was, what it was made out of, whether it was expanding, what was present within it. Today, we have scientific answers to all of these questions to within about 1% accuracy, plus a whole lot more.
The Universe was born almost perfectly uniform, with 1-part-in-30,000 imperfections present on practically all scales. The largest cosmic scales have slightly larger imperfections than the smaller ones, but the smaller ones are also substantial and collapse first. We likely formed the first stars just 50-to-200 million years after the Big Bang; the first galaxies arose 200-to-550 million years after the Big Bang; the largest galaxy clusters took billions of years to get there.
The Universe is neither top-down nor bottom-up, but a combination of both that implies it was born with an almost scale-invariant spectrum. With future survey telescopes such as LSST, WFIRST, and the next-generation of 30-meter-class ground-based telescopes, we’re poised to measure galaxy clustering as never before. After a lifetime of uncertainty, we can finally give a scientific answer to understanding how our Universe’s large-scale structure came to be.”
In a top-down scenario, the Universe would form structures on large scales first, then fragment to form individual galaxies. In a bottom-up scenario, the Universe forms tiny structures first, which then collect and clump under their own gravity to bring about a Universe rich in large-scale structure. So, which one is the Universe we have?
As is often the case, the answer is much more complex than just one of these two possibilities. Come get the full story today.
Three Astrophysicists Reveal Structure Of Universe To Win The 2019 Nobel Prize
“This Nobel is also notable for the elegant way in which it handled a number of controversies. Scientists who work on exoplanets and on large-scale cosmology often compete with one another for funding and resources, but rely on telescopes with similar technologies and often mission-share, as they will with WFIRST and the James Webb Space Telescope. Awarding a Nobel to both cosmology and exoplanets together is a bridge between these two sub-fields, and may encourage them to pursue more joint missions in the future.
Similarly, there were about a dozen Nobel-worthy individuals in the field of exoplanet sciences, with the elephant in the room being that one of the field’s most influential scientists is a known and repeated sexual harasser. In granting a Nobel to Mayor and Queloz, the committee rewarded the exoplanet community while gracefully sidestepping a potential public relations catastrophe.”
The 2019 Nobel Prize in Physics is here, and it goes to three extremely deserving individuals: Jim Peebles, Michel Mayor and Didier Queloz. Mayor and Queloz were the two scientists that, in 1995, unveiled the first confirmed and detected exoplanet around a normal, Sun-like star; it catapulted exoplanet sciences into the mainstream, leading to the rapid development we get to bask in today. Peebles, on the other hand, single-handedly developed the framework for modern physical cosmology, tying observables like galaxy clustering data and CMB fluctuations to the particle properties and energy contents of the Universe.
Peebles also had one student who went on to become a Professor: Jim Fry. That same Jim Fry was my Ph.D. advisor. I believe am the last branch on the Jim Peebles academic tree.
This One Award Was The Biggest Injustice In Nobel Prize History
“Every October, the Nobel foundation awards prizes celebrating the greatest advances in numerous scientific fields. With a maximum of three winners per prize, many of history’s most deserving candidates have gone unrewarded. However, the greatest injustices occurred when the scientists behind the most worthy contributions were snubbed.”
Imagine this scenario: you work hard all your life investigating some aspect of reality with as much scientific rigor as anyone ever has. You make a great breakthrough working on a very hard problem, and you push your scientific field forward in a novel, important, and unprecedented way. And then, when the time comes to evaluate the quality and impact of your work, it’s chosen as being Nobel-worthy.
Only, when they announce the winners of the Nobel Prize, your name isn’t called at all. Instead, other scientists are awarded the prize, while both your name and your decisive work are omitted from every aspect of the award. Sounds like a pretty big injustice, yes?
Well, it’s happened to many people over the years, including Chien-Shiung Wu in perhaps the greatest injustice of them all. Come get the full story on the eve of the 2019 Nobel Prize in physics being awarded!