Sunday, January 22, 2017

ScienceBlogs Channel : Physical Science

ScienceBlogs Channel : Physical Science


Ask Ethan: Is Zero Gravity Really A Thing? (Synopsis) [Starts With A Bang]

Posted: 21 Jan 2017 07:08 AM PST

“It was a strange lightness, a drifting feeling. Zero gravity. I understood that everything that once seemed solid and immovable might just float away.” -Lisa Unger

If you want to experience zero gravity, all you need to do is go to space, turn your rocket off and feel that weightless sensation, right? Except, from up there in Earth's orbit, the gravitational force on you is still almost as great as it is on Earth's surface! You still accelerate down towards the center of the Earth, not quite at 9.8 m/s^2, but not by much less.

Astronauts, and fruit, aboard the International Space Station. Note that gravity isn't turned off, but that everything -- including the spacecraft -- is uniformly accelerated, resulting in a zero-g experience. Public domain image.

Astronauts, and fruit, aboard the International Space Station. Note that gravity isn’t turned off, but that everything — including the spacecraft — is uniformly accelerated, resulting in a zero-g experience. Public domain image.

There's no place in the Universe where you can go to hide from the long-range force of gravity; its effects reach everywhere. So how, then, can we claim to truly know what it's like in a zero-gravity environment? Because zero gravity isn't about turning gravity off; it's about the forces we do (and don't) experience on our bodies.

The identical behavior of a ball falling to the floor in an accelerated rocket (left) and on Earth (right) is a demonstration of Einstein's equivalence principle. Image credit: Wikimedia Commons user Markus Poessel, retouched by Pbroks13.

The identical behavior of a ball falling to the floor in an accelerated rocket (left) and on Earth (right) is a demonstration of Einstein’s equivalence principle. Image credit: Wikimedia Commons user Markus Poessel, retouched by Pbroks13.

According to Einstein, free-fall and zero gravity are actually equivalent, although that's far from obvious. Here's the science behind why on this week's Ask Ethan!

OrbitalHub

OrbitalHub


SBIRS GEO Flight 3

Posted: 21 Jan 2017 12:57 PM PST

The Space-Based Infrared System (SBIRS) is a consolidated system intended to meet the United States' infrared space surveillance needs through the first two to three decades of the 21st century. The SBIRS program is designed to provide key capabilities in the areas of missile warning, missile defense and battlespace characterization.

Please visit OrbitalHub to read more...

Saturday, January 21, 2017

Mathematics of Stem Cells

Mathematics of Stem Cells


Mathematics of Stem Cells

Posted: 21 Jan 2017 09:03 AM PST

Presented by the University of California Irvine School of Physical Sciences. Cell populations are complex. Their collective functioning, turnover, and cooperation are at the basis of the life of multicellular organisms, such as humans. When this goes wrong, an unwanted evolutionary process can begin that leads to cancer. Mathematics cannot cure cancer, but it can be used to understand some of its aspects, which is an essential step in winning the battle.

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