Live, Know, Think

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Measuring the electromagnetic spectrum

You actually know more about it than you may think! The electromagnetic (EM) spectrum is just a name that scientists give a bunch of types of radiation when they want to talk about them as a group. Radiation is energy that travels and spreads out as it goes– visible light that comes from a lamp in your house and radio waves that come from a radio station are two types of electromagnetic radiation. Other examples of EM radiation are microwaves, infrared and ultraviolet light, X-rays and gamma-rays. Hotter, more energetic objects and events create higher energy radiation than cool objects. Only extremely hot objects or particles moving at very high velocities can create high-energy radiation like X-rays and gamma-rays.

The different types of radiation in the EM spectrum, in order from lowest energy to highest:

Radio: Yes, this is the same kind of energy that radio stations emit into the air for your boom box to capture and turn into your favorite Mozart, Madonna, or Justin Timberlake tunes. But radio waves are also emitted by other things … such as stars and gases in space. You may not be able to dance to what these objects emit, but you can use it to learn what they are made of.

Microwaves: They will cook your popcorn in just a few minutes! Microwaves in space are used by astronomers to learn about the structure of nearby galaxies, and our own Milky Way!

Infrared: Our skin emits infrared light, which is why we can be seen in the dark by someone using night vision goggles. In space, IR light maps the dust between stars.

Visible: Yes, this is the part that our eyes see. Visible radiation is emitted by everything from fireflies to light bulbs to stars … also by fast-moving particles hitting other particles.

Ultraviolet: We know that the Sun is a source of ultraviolet (or UV) radiation, because it is the UV rays that cause our skin to burn! Stars and other “hot” objects in space emit UV radiation.

X-rays: Your doctor uses them to look at your bones and your dentist to look at your teeth. Hot gases in the Universe also emit X-rays .

Gamma-rays: Radioactive materials (some natural and others made by man in things like nuclear power plants) can emit gamma-rays. Big particle accelerators that scientists use to help them understand what matter is made of can sometimes generate gamma-rays. But the biggest gamma-ray generator of all is the Universe! It makes gamma radiation in all kinds of ways.

Sheena Iyengar studies how we make choices — and how we feel about the choices we make. At TEDGlobal, she talks about both trivial choices (Coke v. Pepsi) and profound ones, and shares her groundbreaking research that has uncovered some surprising attitudes about our decisions.

A lot of people still believe global warming is something Al Gore cooked up in 2006 to promote his movie.
The thousands of expert climate scientists whose work forms the consensus have no celebrity, no street cred with the average person. But for a lot of people, the archetypes of scientific expertise, are more popular media figures like Stephen Hawking and Carl Sagan.
I offer this to, once again, make clear again how wide and deep the consensus on this issue is.

The Standard Model Of Particle Physics

Sure, the web connects the globe, but most of us end up hearing mainly from people just like ourselves. Blogger and technologist Ethan Zuckerman wants to help share the stories of the whole wide world. He talks about clever strategies to open up your Twitter world and read the news in languages you don’t even know.

At TEDGlobal 2010, author Matt Ridley shows how, throughout history, the engine of human progress has been the meeting and mating of ideas to make new ideas. It’s not important how clever individuals are, he says; what really matters is how smart the collective brain is.

The planck length is unimaginably small.

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“Imagining the Tenth Dimension – a new way of thinking about time and space” by Rob Bryanton, from tenthdimension.com

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