Split-brain

Definition
Split-brain is when the two hemispheres of the brain (left & right) are not connected. This is often due to surgery in which the corpus callosum is severed to avoid the spread of epileptic seizures.

(Video: YouTube)

Commentary
One might think that severing all of the connections between the two hemispheres would lead to significant impairment of functioning, yet the two halves continue to communicate-- just outside of the body (e.g., writing, talking, pointing).

There have been cases, however, in which patients behave as though they have two personalities:

Case 1...would sometimes find himself pulling his pants down with one hand and pulling them up with the other. Once, he grabbed his wife with his left hand and shook her violently, with the right hand trying to come to his wife's aid in bringing the left belligerent hand under control. Once, while I was playing horseshoes with the patient in his backyard, he happened to pick up an ax with his left hand. Because it was entirely likely that the more aggressive right hemisphere might be in control, I discretely left the scene-not wanting to be the victim for the test case of which half-brain does society punish or execute. (Gazzaniga 1970, p.107)

I wouldn't want to be the test case either.

Inattentional Blindness

Definition
Inattentional blindness is an explanation for our inability to see certain changes that are usually considered obvious.

(Video: YouTube)

Commentary
Derren Brown has demonstrated this effect with different races, accents, and even genders! While the original studies had a fail rate of 75%, Brown's informal study had about a 50% fail rate.

Meta
Think of all the things we don't notice. Did you notice that in the first video the color of the presenter's shirt changed?

See Also

• Person Swap at YouTube for Derren Brown's version of this experiment.
• What Clown on a Unicycle? Studying Cellphone Distraction at The New York Times for a discussion about a similar phenomenon.

Wireless Electricity

Note: This post contains embedded video which may not appear in your RSS reader. Click here to view the full post.

Summary
Wires are commonly associated with electricity. It is surprising, therefore, that people thought electricity would never be adopted widely if wires were required. Yet it was adopted, but we've only recently started to shed the wires.

(Video: TED)

Commentary
Earlier efforts focused on charging pads such by PureEnergy and SlashPower. The cleverness of MIT's technique is that it combines induction with resonance to achieve power at larger distances. That is, the resonance allows more of the power to be transmitted via induction to the receiver.

Meta
What are other potential uses of wireless electricity?

Electromagnetic Induction

Definition
From Wikipedia:

Electromagnetic induction is the production of voltage across a conductor situated in a changing magnetic field or a conductor moving through a stationary magnetic field.

In other words, magic.

One toroid to rule them all. Or not.
(Photo: Wikimedia)

Commentary
Induction is the principle behind generating electricity, most electrical motors, and some "smart" traffic lights. It's also how that little bit of foil gets attached to pill bottles and other containers.

More on this later.

See Also

• Concepts in Science: Electromagnetic Induction for an 80's video that's long, but informative.

Resonance

Definition
Resonance refers to a tendency of a system to oscillate more at certain frequencies than at others. Those frequencies are known as resonant frequencies.

(Photo: stevenduong on Flickr)

Commentary
An excellent example of acoustic resonance is shattering a wine glass with sound. Here's a quick explanation as to why the glass shatters:

1. The sound is being generated by a speaker. The speaker works by moving a small cone back and forth generating the appropriate frequency. You can sometimes see the movements.
   
   
2. Many frequencies make the glass vibrate, but only a handful make it vibrate so much that it cannot stay together. Those frequencies are the resonant frequencies-- they make the glass vibrate (i.e. oscillate) much more than the other frequencies.
   
   
3. Since the glass is insufficiently elastic, it shatters.

Meta
What other resonant systems have you encountered?