Priyamvada Natarajan is an astrophysicist at Yale University who specializes in studying the invisible universe: black holes and dark matter. You can read more about her work and how astronomers study what they cannot see in "Mapping the Heavens: The Radical Scientific Ideas That Reveal the Cosmos."
“We know more about the stars high above our heads, than about Earth just below our feet,” lamented Renaissance artist and naturalist Leonardo da Vinci. In the episode the “Horta”, as this creature is called, feeds on solid rock and requires the prohibitive conditions found in the underground, a cold, dry and oxygen-free world with no sunlight, to survive. On a superficial glimpse (pun intended) such life seems impossible, however there are many real examples found in Earth’s underground, showing that lifeforms have evolved to survive even in extreme conditions. Terrestrial organisms, like the lichen species Toninia candida (looking surprisingly similar to the Horta), extract essential nutrients from rocks, some microorganisms however are able to make a living solely relying on rocks (image by the author).
The invisible and unseen has always fascinated us humans. Mapping both literal and metaphorical has always been about our quest for knowing. As an astrophysicist, my research work involves mapping dark matter, the elusive substance that accounts for about a quarter of our universe. This is, though, not the first attempt to map the unknown. The deep fascination with the mysterious, and the impulse to seek and locate ourselves in the cosmic context, seems to be imprinted in our DNA and psyches. Curiosity propelled the ancients to travel beyond familiar shores and to build instruments to chart both the terra firma's extent - and their place on it. The night sky offered a different perspective -
We are moving from A to B. Yet everywhere we look, we are going backwards! I mean the direction we are moving along [trajectory] must [?] have something in front of earth-solar system-galaxy. Yet it is all the past. No future! Now could this be because we are at the event horizon [so to speak] the very edge of the beginning? However one ‘material’ that has moved faster-than-light is space. Light is still catching up. Why can’t we see even this? There’s a couple things blurring together here, but the fundamental thing here is the distinction between the observable universe and the universe which exists, independent of our ability to observe it. You’ve got a good handle on the observable universe.
You might think of the largest and most powerful particle accelerators in the world - places like SLAC, Fermilab and the Large Hadron Collider - as the source of the highest energies we’ll ever see. But everything we’ve ever done here on Earth has absolutely nothing on the natural Universe itself! In fact, if you were interested in the most energetic particles on Earth, looking at the Large Hadron Collider - at the 13 TeV collisions occurring inside - you wouldn’t even be close to the highest energies. Sure, those are the highest human-made energies for particles, but we’re constantly bombarded all the time by particles far, far greater in energy from the depths of space itself: cosmic rays.
The Rosetta mission is dispelling the notion that comets are leftover bits from crushing cosmic collisions. Instead, analysis of data from the European Space Agency mission to Comet 67P/Churyumov-Gerasimenko suggests that the icy bodies could actually be leftover from the primordial process of Solar System formation. A new study using Rosetta data and led by Björn Davidsson of NASA's Jet Propulsion Laboratory has been published in the journal Astronomy & Astrophysics laying out the evidence that comets are older remnants of the cosmos rather than younger bits of debris from violent space impacts. "Either way, comets have been witness to important Solar System evolution events, and this is why we have made these detailed measurements with Rosetta - along with observations of other comets - to find out which scenario is more likely," says Matt Taylor, ESA's Rosetta project scientist.
There is something strange happening in the local universe, with galaxies moving away from each other faster than expected. What is driving this extra expansion, and what does it mean for the cosmos? To explore this, let’s start with the observations. The rate of cosmic expansion is encapsulated in the “Hubble constant”, although don’t let the name fool you, as it’s not a constant and changes as the universe expands. To determine this constant, astronomers must relate the distances to galaxies to the velocity they’re travelling away from us. But measuring astronomical distances has always proven difficult. This is because we lack convenient signposts, known as standard candles and rulers, to
The discovery of gravitational waves in February is leading to remarkable new insights in physics. One of the most promising is identifying what dark matter is made of, the elusive missing majority of the universe that we know is out there but can’t detect directly. NASA Cosmologist Alexander Kashlinsky thinks that black holes could be the answer, and that detecting gravitational waves could be the best way to confirm it. Here’s how. Video courtesy of NASA. Follow TI: On Facebook
Most of the forces and phenomena in the Universe have causes that can be easily uncovered. Two massive objects experience a gravitational force due to the fact that spacetime is curved by the presence of matter and energy. The Universe has expanded as it has over its history because of the changing energy density of the Universe and the initial expansion conditions. And all the particles in the Universe experience the interactions they do because of the known rules of quantum field theory and the exchange of vector bosons. From the smallest, subatomic particles to the largest scales of all, the same forces are at play, holding everything from protons to people to planets to galaxies together.
It’s poetic justice on a cosmic scale. The same galaxy that the Milky Way is tearing apart may be responsible for a mysterious warp in our galaxy’s disc. Approximately 50 galaxies orbit our own. The two brightest, the Large and Small Magellanic Clouds, were once thought to be the nearest as well. But in 1994 astronomers spotted a galaxy on the far side of the Milky Way in the constellation Sagittarius that’s only 80,000 light years from Earth - half the distance to the Large Magellanic Cloud. The Sagittarius dwarf galaxy is so close that the Milky Way’s gravitational pull is tearing it apart, spilling its stars and star clusters into long streams. But now it seems that this victimised galaxy
