Thinking About the Universe
For the first time, scientists have discovered a classic formula for pi in the world of quantum physics. Pi is the ratio between a circle’s circumference and its diameter, and is incredibly important in pure mathematics, but now scientists have also found it “lurking” in the world of physics, when using quantum mechanics to compare the energy levels of a hydrogen atom.
Why is that exciting? Well, it reveals an incredibly special and previously unknown connection between quantum physics and maths.
“I find it fascinating that a purely mathematical formula from the 17th century characterises a physical system that was discovered 300 years later,” said one of the lead researchers, Tamar Friedmann, a mathematician at the University of Rochester in the US. Seriously, wow.
View full lesson: http://ed.ted.com/lessons/dark-matter…
The Greeks had a simple and elegant formula for the universe: just earth, fire, wind, and water. Turns out there’s more to it than that — a lot more. Visible matter (and that goes beyond the four Greek elements) comprises only 4% of the universe. CERN scientist James Gillies tells us what accounts for the remaining 96% (dark matter and dark energy) and how we might go about detecting it.
Lesson by James Gillies, animation by TED-Ed.
The largest sample yet of the faintest and earliest known galaxies in the universe, revealed by Hubble. Some formed just 600 million years after the Big Bang.
This image from the NASA/ESA Hubble Space Telescope shows the galaxy cluster MACS J0416.1–2403. This is one of six being studied by the Hubble Frontier Fields programme, which together have produced the deepest images of gravitational lensing ever made. Due to the huge mass of the cluster it is bending the light of background objects, acting as a magnifying lens. Astronomers used this and two other clusters to find galaxies which existed only 600 to 900 million years after the Big Bang.
View larger. | The galaxy cluster MACS J0416.1–2403. It’s being studied by the Hubble Frontier Fields program. Due to the huge mass of the cluster it is bending the light of background objects, acting as a gravitational lens. Astronomers used this and two other clusters to find galaxies which existed only 600 to 900 million years after the Big Bang.
If we could look far enough away in space – and therefore far enough back in time – could we see the beginnings of the universe? The answer is surely yes, and now the Hubble Space Telescope has looked over 12 billion light-years away, and thus that far back in time, to create the largest sample yet of the faintest and earliest known galaxies in our universe. A technique called gravitational lensing revealed these galaxies, which existed at a time when our universe was very young. A Hubble website said this week (October 22, 2015) that some of these galaxies formed just 600 million years after the Big Bang.
According to a well-known theory in quantum physics, a particle’s behavior changes depending on whether there is an observer or not. It basically suggests that reality is a kind of illusion and exists only when we are looking at it. Numerous quantum experiments were conducted in the past and showed that this indeed might be the case.
Now, physicists at the Australian National University have found further evidence for the illusory nature of reality. They recreated the John Wheeler’s delayed-choice experiment and confirmed that reality doesn’t exist until it is measured, at least on the atomic scale.