A Pixelated Space...

The search for signatures of quantum gravity forges ahead.
Sand dunes seen from afar seem smooth and unwrinkled, like silk sheets spread across the desert. But a closer inspection reveals much more. As you approach the dunes, you may notice ripples in the sand. Touch the surface and you would find individual grains. The same is true for digital images: zoom far enough into an apparently perfect portrait and you will discover the distinct pixels that make the picture.

The universe itself may be similarly pixelated. Scientists such as Rana Adhikari, professor of physics at Caltech, think the space we live in may not be perfectly smooth but rather made of incredibly small discrete units. “A spacetime pixel is so small that if you were to enlarge things so that it becomes the size of a grain of sand, then atoms would be as large as galaxies,” he says.

Adhikari and scientists around the world are on the hunt for this pixelation because it is a prediction of quantum gravity, one of the deepest physics mysteries of our time. Quantum gravity refers to a set of theories, including string theory, that seeks to unify the macroscopic world of gravity, governed by general relativity, with the microscopic world of quantum physics. At the core of the mystery is the question of whether gravity, and the spacetime it inhabits, can be “quantized,” or broken down into individual components, a hallmark of the quantum world.

“Sometimes there is a misinterpretation in science communication that implies quantum mechanics and gravity are irreconcilable,” says Cliff Cheung, Caltech professor of theoretical physics. “But we know from experiments that we can do quantum mechanics on this planet, which has gravity, so clearly they are consistent. The problems come up when you ask subtle questions about black holes or try to merge the theories at very short distance scales.”

Because of the incredibly small scales in question, some scientists have deemed finding evidence of quantum gravity in the foreseeable future to be an impossible task. Although researchers have come up with ideas for how they might find clues to its existence—around black holes; in the early universe; or even using LIGO, the National Science Foundation-funded observatories that detect gravitational waves—no one has yet turned up any hints of quantum gravity in nature.  READ MORE...

STEM Education in the USA

VISION STATEMENT

“All citizens can contribute to our nation’s progress and vibrancy. To be prepared for the STEM careers of the future, all learners must have an equitable opportunity to acquire foundational STEM knowledge. The STEM Education of the Future brings together our advanced understanding of how people learn with modern technology to create more personalized learning experiences, to inspire learning, and to foster creativity from an early age. It will unleash and harness the curiosity of young people and adult learners across the United States, cultivating a culture of innovation and inquiry, and ensuring our nation remains the global leader in science and technology discovery and competitiveness.”

Rapid technological advancements and societal changes are our daily reality. While the future of work, the economy, and society is uncertain, one thing is not: To maintain the nation’s leadership in science and technology discovery, we must create an approach to science, technology, engineering, and math (STEM) education that prepares and advances the U.S. for this future.

Experts agree that science, technology, engineering and math will drive new innovations across disciplines, making use of computational power to accelerate discoveries and finding creative ways to work across disciplinary silos to solve big challenges. To remain competitive going forward, our nation must continue to design and build a thriving innovation economy, supported by a citizenry that is invested in the STEM enterprise. To succeed, the nation must invest in new research and innovation infrastructures that include all people, regardless of their background.

HOW DO WE ACHIEVE THIS VISION?

We instill creativity, innovation, and a passion for STEM from an early age, and we maintain that engagement and enthusiasm throughout their lives. Doing so will unleash an innovation culture, teaching learners of all ages to take risks, be creative, and problem-solve. Today, we are far from this goal. 

Many Americans are entering the workforce without a basic grasp of STEM facts and approaches. Equally worrisome, amid the stagnant or dipping numbers of U.S.-born STEM workers, there is a critical lack of women, people with disabilities and African Americans, Hispanic Americans, and Native Americans who remain underrepresented in STEM. This underrepresentation is especially evident in several strategic areas critical for U.S. progress and security, including computer science, mathematics, and engineering. 

We are in dire need of STEM role models and leaders for the future. By 2060,1 Black and Hispanic youth will comprise nearly half of all U.S. school-age children. However, STEM faculty from these backgrounds are currently scarce, and trends among the number of domestic students who pursue advanced research degrees in STEM disciplines—particularly computer science, mathematics, and engineering...  READ MORE...

Big Bang Isn't the Beginning

The modern cosmic picture of our universe’s history begins not with a singularity, the Big Bang, 

but rather with a period of cosmic inflation that stretches a flat, uniform universe. The end of 

inflation is the onset of Hot Big Bang., Nicole Rager Fuller/National Science Foundation)

KEY TAKEAWAYS

• The Big Bang teaches us that our expanding, cooling universe used to be younger, denser, and hotter in the past.
• However, extrapolating all the way back to a singularity leads to predictions that disagree with what we observe.
• Instead, cosmic inflation preceded and set up the Big Bang, changing our cosmic origin story forever.

Where did all this come from? In every direction we care to observe, we find stars, galaxies, clouds of gas and dust, tenuous plasmas, and radiation spanning the gamut of wavelengths: from radio to infrared to visible light to gamma rays. No matter where or how we look at the universe, it’s full of matter and energy absolutely everywhere and at all times. 

And yet, it’s only natural to assume that it all came from somewhere. If you want to know the answer to the biggest question of all — the question of our cosmic origins — you have to pose the question to the universe itself, and listen to what it tells you.

Today, the universe as we see it is expanding, rarifying (getting less dense), and cooling. Although it’s tempting to simply extrapolate forward in time, when things will be even larger, less dense, and cooler, the laws of physics allow us to extrapolate backward just as easily. Long ago, the universe was smaller, denser, and hotter. 

How far back can we take this extrapolation? Mathematically, it’s tempting to go as far as possible: all the way back to infinitesimal sizes and infinite densities and temperatures, or what we know as a singularity. This idea, of a singular beginning to space, time, and the universe, was long known as the Big Bang.

But physically, when we looked closely enough, we found that the universe told a different story. Here’s how we know the Big Bang isn’t the beginning of the universe anymore.  READ MORE...