Why Even Einstein Couldn’t Unite Physics

Einstein Lecturing
Albert Einstein during a lecture in Vienna in 1921. Credit: National Library of Austria/F Schmutzer/Public Domain

Near the end of his life Einstein worked tirelessly to find a way to unite electromagnetism with gravity. He could not, and never did, the notes scattered on his desk scrawled with fruitless probes and useless hypotheticals. Indeed, Einstein passed without even understanding why the two forces could not be united.

Continue reading “Why Even Einstein Couldn’t Unite Physics”

How Einstein Unlocked the Quantum Universe and Created the Photon

This all-sky Fermi view includes only sources with energies greater than 10 GeV. From some of these sources, Fermi's LAT detects only one gamma-ray photon every four months. Brighter colors indicate brighter gamma-ray sources. Credit: NASA/DOE/Fermi LAT Collaboration

It started with a simple experiment that was all the rage in the early 20th century. And as is usually the case, simple experiments often go on to change the world, leading Einstein himself to open the revolutionary door to the quantum world.

Continue reading “How Einstein Unlocked the Quantum Universe and Created the Photon”

How to Think About a Four-Dimensional Universe

Hubble image of SDSSJ0146-0929, a galaxy cluster that is massive enough to severely distort the spacetime around it. There's the mass of the visible stars and gas, but there's also a hidden amount of dark matter that adds to the cluster's mass. Credit: ESA/Hubble & NASA; Acknowledgment: Judy Schmidt
Hubble image of SDSSJ0146-0929, a galaxy cluster that is massive enough to severely distort the spacetime around it. There's the mass of the visible stars and gas, but there's also a hidden amount of dark matter that adds to the cluster's mass. Credit: ESA/Hubble & NASA; Acknowledgment: Judy Schmidt

In Einstein’s famous theory of relativity the concepts of immutable space and time aren’t just put aside, they’re explicitly and emphatically rejected. Space and time are now woven into a coexisting fabric. That is to say, we truly live in a four-dimensional universe. Space and time alone cease to exist; only the union of those dimensions remains.

Continue reading “How to Think About a Four-Dimensional Universe”

Is Anything Absolute with Relativity?

Researchers crunched Einstein's theory of general relativity on the Columbia supercomputer at the NASA Ames Research Center to create a three-dimensional simulation of merging black holes. Image Credit: Henze, NASA

The theory of relativity is at once simple and elegant but also maddeningly nonintuitive. There’s no need to get into the full guts and glory of that theory here, but there is one feature of Einstein’s work that takes center stage, and would eventually lead him into a complete reshaping of Newton’s gravity, altering our very conceptions of the fabric of the universe.

Continue reading “Is Anything Absolute with Relativity?”

‘Her Space, Her Time’ Reveals the Hidden Figures of Physics

Sepia-tone photos of Leavitt, Payne-Gaposchkin, Rubin and Alexander
These are just four of the women physicists profiled in "Her Space, Her Time": Henrietta Swan Leavitt, Cecilia Payne-Gaposchkin, Vera Rubin and Claudia Alexander. (Credits: Wikimedia; Smithsonian Institution; Rubin photo by Mark Godfrey, courtesy of AIP Emilio Segre Visual Archives; NASA)

Quick: Name a woman scientist.

Chances are the name you came up with is Marie Curie, the physicist and chemist who won two Nobel Prizes more than a century ago for the discoveries she and her husband Pierre made about radioactivity.

But who else? In a new book titled “Her Space, Her Time,” quantum physicist Shohini Ghose explains why women astronomers and physicists have been mostly invisible in the past — and profiles 20 researchers who lost out on what should have been Nobel-level fame.

“This issue around having low representation of women in physics is something that’s common all around the world,” Ghose says in the latest episode of the Fiction Science podcast. “And I’ve certainly faced it in my own experiences as a physicist growing up. I really didn’t know of any woman physicist apart from Marie Curie.”

Continue reading “‘Her Space, Her Time’ Reveals the Hidden Figures of Physics”

Thinking About Time Travel Helps Solve Problems in Physics

Physicists have shown that simulating models of hypothetical time travel can solve experimental problems that appear impossible to solve using standard physics. Credit: Yaroslav Kushta via Getty Images

Time travel. We’ve all thought about it at one time or another, and the subject has been explored extensively in science fiction. Once in a while, it is even the subject of scientific research, typically involving quantum mechanics and how the Universe’s four fundamental forces (electromagnetism, weak and strong nuclear forces, and gravity) fit together. In a recent experiment, researchers at the University of Cambridge showed that by manipulating quantum entanglements, they could simulate what could happen if the flow of time were reversed.

Continue reading “Thinking About Time Travel Helps Solve Problems in Physics”

It's Official, Antimatter Falls Down in Gravity, Not Up

Illustration of how anti-hydrogen can test gravity. Credit: National Science Foundation

It’s a basic fact we’ve all learned in school. Drop any object, be it a baseball, feather, or cat, and it will fall toward the Earth at exactly the same rate. The cat will fortunately land on its feet thanks to a bit of feline grace, but the point is that everything falls at the same rate under gravity. It doesn’t matter what an object is made of, or how heavy it is. While we’ve all been taught this fact, calling it a fact was, until recently, a bit of a lie.

Continue reading “It's Official, Antimatter Falls Down in Gravity, Not Up”

Gluttonous Black Holes Eat Faster Than Thought. Does That Explain Quasars?

Illustration of an active quasar. What role does its dark matter halo play in activating the quasar? Credit: ESO/M. Kornmesser
Illustration of an active quasar. New research shows that SMBHs eat rapidly enough to trigger them. Credit: ESO/M. Kornmesser

At the heart of large galaxies like our Milky Way, there resides a supermassive black hole (SMBH.) These behemoths draw stars, gas, and dust toward them with their irresistible gravitational pull. When they consume this material, there’s a bright flare of energy, the brightest of which are quasars.

While astrophysicists think that SMBHs eat too slowly to cause a particular type of quasar, new research suggests otherwise.

Continue reading “Gluttonous Black Holes Eat Faster Than Thought. Does That Explain Quasars?”

New Muon g-2 Result Improves the Measurement by a Factor of 2

First results from the Muon g-2 experiment at Fermilab have strengthened evidence of new physics. Credit: Reidar Hahn/Fermilab

At the Fermi National Accelerator Laboratory (aka. Fermilab), an international team of scientists is conducting some of the most sensitive tests of the Standard Model of Particle Physics. The experiment, known as Muon g-2, measures the anomalous magnetic dipole moment of muons, a fundamental particle that is negatively charged (like electrons) but over 200 times as massive. In a recent breakthrough, scientists at Fermilab made the world’s most precise measurement of the muon’s anomalous magnetic moment, improving the precision of their previous measurements by a factor of 2.

Continue reading “New Muon g-2 Result Improves the Measurement by a Factor of 2”