Category: physics

Euler’s identity – beauty in its purest form.

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.

Again and again the principle of least action catches me – it’s too damn beautiful.

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.

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!

This one made me laugh

This One Puzzle Brought Physicists From Special To General Relativity

“With an average speed of 47.36 km/s, Mercury moves very slow compared to the speed of light: at 0.0158% the speed of light in a vacuum. However, it moves at this speed relentlessly, every moment of every day of every year of every century. While the effects of Special Relativity might be small on typical experimental timescales, we’ve been watching the planets move for centuries.

Einstein never thought about this; he never thought to calculate the Special Relativistic effects of Mercury’s rapid motion around the Sun, and how that might impact the precession of its perihelion. But another contemporary scientist, Henri Poincaré, decided to do the calculation for himself. When he factored in length contraction and time dilation both, he found that it led to approximately another 7-to-10 arc-seconds of orbital precession per century.“

Special Relativity was easy enough to discover in a certain sense: the Lorentz transformations, Maxwell’s equations, and the Michelson-Morley experiments had been around for decades before Einstein came along. But to go from Special Relativity to General Relativity, incorporating gravitation and the equations governing motion into the same framework, was a herculean effort. However, it was the simple identification and investigation of one puzzle, the orbit of Mercury around the Sun, that brought about Einstein’s new theory of gravity: General Relativity.

What were the key steps, and how did they help revolutionize our view of the Universe? The history is rich and spectacular, and holds a lesson for those on the frontiers of physics today.

This One Thought Experiment Shows Why Special Relativity Isn’t The Full Story

“In Einstein’s initial formulation of General Relativity way back in 1916, he mentioned the gravitational redshift (and blueshift) of light as a necessary consequence of his new theory, and the third classical test, after the precession of Mercury’s perihelion (already known at the time) and the deflection of starlight by a gravitational source (discovered during a total solar eclipse in 1919).

Although a thought experiment is an extremely powerful tool, practical experiments didn’t catch up until 1959, where the Pound-Rebka experiment finally measured a gravitational redshift/blueshift directly. Yet just by invoking the idea that energy must be conserved, and a basic understanding of particle physics and gravitational fields, we can learn that light must change its frequency in a gravitational field.”

If a photon flies through space towards Earth, it must gain energy and become bluer in nature as it approaches Earth’s surface. This idea, of a gravitational redshift or blueshift, dictates how a photon must change in energy in the presence of a gravitational field. Yet this effect, which only exists in General Relativity, could have been predicted as soon as special relativity was discovered by one simple thought experiment: to consider a particle-antiparticle pair dropped from high above the surface of the Earth, but to let the annihilation occur at varying locations.

If you considered that, you’d immediately realize how special relativity was insufficient for describing our Universe! Come learn how to reason it out for yourself today!