Does the Fourth dimension have practical use?

The fourth dimension is part of our lives whether we like it or not. That’s because the fourth dimension is time. When you make a graph of position vs time, you have used the fourth dimension. Because our senses can only interact with one point in the fourth dimension though (the time we call now) we just don’t usually notice it.

Using the fourth dimension as it works in Einstein’s Special Theory of Relativity however is a little more involved, this is because time is affected by speed.

Basically the combined speed of any object’s motion through space and it’s motion though time is always precisely equal to the speed of light.

That’s right, everything. You, me, the computer screen you’re looking at, everything.

Everything is travelling through Spacetime: space (the three dimensions we experience) and time.

Adding the total movement through both space and time always equals light speed. Always. Always. Always.

Since you must travel constantly at exactly the speed of light, when you increase your speed through space, you decrease your speed through time.

So taking all the above in consider this.

Your head (and the rest of you) is travelling through spacetime at the speed of light. But, when you’re at rest (not accelerating) all of your head’s movement is through time, none of it is travelling (accelerating) through space. Every time your head moves (accelerates) through space; in a car, in a plane, in a spaceship… even nodding up and down, some of it’s movement in time is lost since it is now moving through space. Cool huh.

Ps. All hail to Brian Greene for the above analogy.

You never hear the one that hits you. or do you?

“You never hear the one that hits you” was the fatalistic saying on the front trenches of many wars (not to mention the song of the same name by the rock group Stiff Little Fingers).

Well, it turns out that the soldiers and the punk rockers had their physics spot on, a bullet travels faster than the speed of sound and will arrive at its destination before the sound of the gun firing gets there. So if you’re still standing when you hear the gunshot, congratulations you’re going to live!

Something for the Weekend

This weekends plaything is brought to you by Microsoft Research (don't worry Mac users it works on Macs too). Its a virtual telescope called World wide Telescope or WWT. It has tours and allows sky scanning at multiple wavelengths for the hardcore. Basically its like having access to Hubble for free.

Having played around with it for a bit, I recommend the tours they are excellent and there are loads of them!

http://www.worldwidetelescope.
org/ExperienceIt/ExperienceIt . aspx#

To get started all you need to do is press RUNWEBCLIENT in the top left.

Your brain and booze

Most everyone knows that alcohol impairs mental and physiological functions, but what actually goes on at the cellular level when you drink a beer?

Alcohol interferes with the normal function of your brain cells.

Under normal circumstances, each of your brain cells allows various substances, such as sodium, calcium and potassium to permeate its outer cell membrane.

Once inside the brain cell, these substances help give the cell stimulus it needs to function properly. Then they leave the cell and allow another set of these substances to begin the cycle again.

The millions of cells that make up your brain are continually allowing these substances to penetrate their membranes and then expelling these same substances later. All of this action allows the brain to interpret and transport messages.

Alcohol consumption prevents sodium from being able to cross brain cell membranes. Once even this part of the cycle breaks down, brain functions become impaired.

You can notice the affects of this break down aftera single drink. Even if you’ve had just one drink, your ability to respond to stimulus decreases and your reaction time slows down.

If you’re driving, you might see a car stop, and know that you need to slam on the brakes, but the pathway in your brain that processes this information and causes you to respond toit will be working in slow motion.

Pioneering Pangaea

It is Alfred Wegener, a German scientist, who first argued that the continents wandered about the globe.

In his 1915 paper The Origin of Continents and Oceans ( Die Entstehung der Kontinente und Ozeane ), Wegener published the theory that there had once been a giant continent, he named "Pangaea" meaning "All-Lands" or "All-Earth" drawing together evidence from various fields.

He argued his theory and gathered evidence to support it until his untimely death in 1930 at the age of 50 on one of his many expeditions. Wegener died a hero losing his life in the snows of Greenland while trying to resupply a camp which desperately needed supplies to survive the winter.

Ultimately the New Earth conceived by Wegener was half a century ahead of its time. It wasn’t until the mid-'60s that geologists generally realized that he was, in essence, right.

Speedy Cernan

The unofficial lunar speed record is held by Gene Cernan who recorded a speed of 11.2mph (18km/hr) driving one of the three lunar rovers used on the moon during Apollo 17( our final visit to luna). The reason the speed is credited as unofficial is that A.no-one other than Cernan and is companion Harrison Schmitt can verify the speed they achieved and B. The lunar rovers top speed was supposed to be only 8mph, so technically they were speeding!

Copious Connections

A piece of your brain the size of a grain of sand would contain, one hundred thousand neurons, two million axons and one billion synapses, all “talking to” each other.

What is Dark Matter and what does it do?

By definition, dark matter is any substance that behaves gravitationally like ordinary matter, but that is invisible to present-day telescopes and detectors. Its existence was first invoked a few decades ago, when astronomers made the startling discovery that the material in the outskirts of spiral galaxies is moving much more rapidly than anticipated from the gravitational pull of their gas and stars alone.

Countless comparisons between the amount of visible matter in astronomical objects and their masses inferred from motions under gravity have since been undertaken. Almost all of these experiments reach the same conclusions: nearly 90% of all matter is dark, and dark and luminous matter combined account for less than 1/3 of total energy density of the Universe (the rest stems from vacuum energy, or dark energy). Quite literally, then, there is much more to space than meets the eye!

While the nature of dark matter remains unknown, observations have revealed 2 of its key properties: First, dark matter is "cold": its characteristic speed must be much lower than that of light even in the very early Universe (otherwise, the smallest galaxies in the vicinity of the Milky Way and other larger systems wouldn't form). Second, dark matter is "collisionless": there are very few interactions among dark matter particles or between dark and luminous particles (in other words, dark matter is indeed invisible, or very nearly so).

The cold collisionless dark matter that pervades the Universe is therefore very different from ordinary matter. It doesn't even contain protons and neutrons, the particles that make up almost everything on Earth. Rather, leading dark matter candidates are exotic weakly interacting massive particles (WIMPs) expected from the supersymmetry theory of particle physics; experiments to test this hypothesis are underway.

Because the amount of dark matter in galaxies and clusters of galaxies dwarfs the amount of ordinary matter they contain, it dominates most gravitational interactions on these scales. For example, the gravitational clustering of dark matter is largely responsible for the formation of galaxies and clusters in the first place!

On smaller scales such as in the Solar System and on Earth, however, dark matter has a negligible gravitational effect. That's because the average dark matter density is much lower (a trillion trillion times lower, in fact!) than that of rocks, water and other substances typically found on Earth. So even though there is dark matter in the Solar System, the latter just isn't big enough for dark matter to play an important dynamical role.

So while dark matter reigns supreme throughout most of the Universe, here at home the protons and neutrons run the show!

Something for the Weekend

I’ve got a couple of things to share this weekend. One is a nice music video and the other a tale of what not to do if you happen to work at a particle accelerator.

The video is called The Poetry of Reality and features a whole host of science luminaries from Sagan to Dawkins and sums up what science is all about.

http://www.youtube.com/watch?v
=9Cd36WJ79z4&feature=playe
r_embedded#

The don’t do this tale is titled “What happens when you stick your head in a particle accelerator?” which is exactly what Anatoli Bugorski did in 1978. What happened next isn’t what scientists expected. He lived! Here is the link to his story.

http://www.todayifoundout.com/
index.php/2010/03/what-happens
-when-you-stick-your-head-into
-a-particle-accelerator/

Ps. Have just been sent a flyover of Mars's Candor Chasma region using HI-RISE DTM data, its well worth a look. Will our children be doing this in an as yet unimagined Mars Flyer?

http://www.youtube.com/watch?v
=0WsjeJiAR4E&feature=playe
r_embedded

Big Baby Blue

Newborn baby blue whales are 25 feet long and weigh 6-8 tonnes (that's as much as an African elephant)