Archive for the ‘Science’ Category
The world’s roundest object helps solve the longest running problem in measurement — how to define the kilogram.
Tides are great bulges of water caused by the gravity of the Moon and Sun. Attracted by gravity, these bulges move around the Earth’s oceans, causing water levels to rise and fall. Typically water will rise for about six hours, followed by six hours of falling water depths. When sped up they look really cool …
Tides explained by MinutePhysics here.
Taylor Wilson believes nuclear fusion is a solution to our future energy needs, and that kids can change the world. And he knows something about both of those: When he was 14, he built a working fusion reactor in his parents’ garage.
Scientists at Massachusetts General Hospital in Boston have fitted rats with kidneys that were grown in a lab from stripped-down kidney scaffolds. When transplanted, these ‘bioengineered’ organs starting filtering the rodents’ blood and making urine just as a normal kidney would.
It is hard to grasp just how small the atoms that make up your body are until you take a look at the sheer number of them. An adult is made up of around 7,000,000,000,000,000,000,000,000,000 (7 octillion) atoms.
On sheer count of cells, there is more bacterial life inside you than human. There are around 10 trillion of your own cells, but 10 times more bacteria. Many of the bacteria that call you home are friendly in the sense that they don’t do any harm. Some are beneficial.
The atoms that make up your body are mostly empty space, so despite there being so many of them, without that space you would compress into a tiny volume. The nucleus that makes up the vast bulk of the matter in an atom is so much smaller than the whole structure that it is comparable to the size of a fly in a cathedral. If you lost all your empty atomic space, your body would fit into a cube less than 1/500th of a centimetre on each side. Neutron stars are made up of matter that has undergone exactly this kind of compression. In a single cubic centimetre of neutron star material there are around 100 million tons of matter.
It might seem hard to believe, but we have about the same number of hairs on our bodies as a chimpanzee, it’s just that our hairs are useless, so fine they are almost invisible. We aren’t sure quite why we lost our protective fur. It has been suggested that it may have been to help early humans sweat more easily, or to make life harder for parasites such as lice and ticks, or even because our ancestors were partly aquatic.
Lots more here.
How much would the sea level fall if every ship were removed all at once from the Earth’s waters?
Archimedes’ principle tells us that the water displaced by a ship weighs as much as the ship itself. If we can figure out the total weight of all the world’s ships, we can figure out how much water they’re displacing, then divide that volume by the surface area of the ocean to figure out how much the water level would drop.
Weighing ships is confusing. There are a bunch of different measurements of the size of a ship, and many of them, like gross tonnage, are actually measures of the volume of the ship’s rooms and other internal spaces, not its weight.
The UN Conference on Trade and Development publishes estimates of the size of the world shipping fleet.
What the UNCTD publishes is “deadweight tonnage”, which is the maximum weight of the ship’s fuel, cargo, and crew. What we want is “displacement”. Unfortunately, comprehensive numbers for displacement are harder to find.
Fortunately, we can estimate it. Brian Barrass’s book Ship Design and Performance for Masters and Mates gives a table of ratios of deadweight tonnage to displacement for different types of ships.
Extrapolating from the last few years of UNCTD data, and using the coefficients from the book, suggests that the world fleet weighs about 2.15 billion tons when fully loaded.
A ton of water is about a cubic meter. 2.15 billion cubic meters divided by the surface area of the oceans equals about 6 microns (0.006 mm).
So there you go, if every ship were removed all at once from the Earth’s waters the sea level would fall by about six microns—slightly more than the diameter of a strand of spider silk. Learn more here.
Heaven meets the Earth in this moving time-lapse video showing gorgeous landscapes underneath an ever-changing night sky.
“Within Two Worlds” was created by photographer Brad Goldpaint. The film features shooting comets, a giant tilting Milky Way, and glowing purple and pink auroras peeking over the horizon. Stunning sequences watch day turn to night and night to day, as overhead stars shine their beautiful light above mountains, forests, and waterfalls.