Science is part of our day-to-day lives be it in the form of all the technology we use or all the underlying mechanisms and principles of the natural world that we take for granted. Our very being is a testament to all the miracles science has to offer, if they can be called miracles. Nevertheless, science is not magic. Whether you are exploring the mysteries of time and space, wondering about the ability of your brain to store information, or looking for an answer to why your shoelaces keep undoing themselves, sometimes the answers are sure to surprise you. Here are explanations for some such surprising scientific facts that we are sure you would enjoy reading about.

1 The black mesh you see on the doors of microwave ovens blocks the waves as they are actually too big to fit through the holes. 

The wavelengths of microwaves are between one meter and one millimeter. Unlike radio waves, microwaves can only travel by line-of-sight and are stopped by anything in the way, though lower frequencies might be able to pass through walls. The frequency used for household purposes is 2.45 GHz which is part of the approved ISM (industry, scientific, and medical) frequency bands and is generated by a component known as a cavity magnetron.

The metal cooking chamber along with the mesh in the door of the microwave oven works as a Faraday cage. A Faraday cage is an enclosed chamber made using a continuous-covering conducting material such as a metal mesh that blocks electromagnetic fields. The holes in the metal mesh of the oven’s door are small enough to block the microwaves which have a wavelength of 12.2 cm for 2.45 GHz frequency but allow visible light for us to check the food. (source)

2 People with brown eyes actually have blue eyes under a layer of melanin. 

The blue color of the eyes is not due to any blue pigment, but rather due to the lack of melanin. Just the way clear sky appears blue, eyes with low concentrations of melanin appear blue as a result of Rayleigh scattering. The underlying dark epithelium of the blue eyes absorbs light of longer wavelengths and the light of shorter wavelengths is reflected by the turbid medium of iris stroma.

Brown eyes have relatively high levels of melanin which absorbs light of both shorter and longer wavelengths. They are dominant in humans and everyone had brown eyes tens of thousands of years ago until a genetic mutation occurred among the people living near the Black Sea that resulted in blue eyes. Nowadays, it is possible to remove the melanin in brown eyes through laser surgery to get blue eyes. (source)

3 Your shoelaces come undone when you are walking or running because the knots are subject to forces up to 7G with every step you take. 

Mechanical engineers at University of California, Berkeley, lead by Christopher Daily-Diamond, conducted a research using a slow-motion camera and a series of experiments and found that the knots come undone in a matter of seconds because of a complex interaction of forces.

When you start running, the foot strikes the ground with a force seven times that of gravity. The knot stretches and relaxes in response to that force and loosens up. When the foot swings backward during the next step, the inertial force on the ends of the lace acts like an invisible hand pulling the knot open. To put that into perspective, the Tower of Terror in Gold Reef City, Johannesburg, South Africa, considered the most powerful roller coaster in the world, holds the record for highest g-force on a roller coaster at 6.3G. (source)

4 Almost 85% of the world’s oxygen is produced in the ocean by phytoplankton.

Phytoplankton are very small drifting organisms that live in the upper layers of almost all water bodies where the sunlight can penetrate. They produce their own food through photosynthesis by consuming the carbon dioxide and releasing molecular oxygen into the water. The phytoplankton produce an estimated 50% to 85% of the world’s oxygen through photosynthesis, while the rest is produced by the plants on land.

Being able to produce their own food means they also form the basis of the aquatic food chain. Small aquatic organisms, such as krill that live in the upper layers, feed on phytoplankton. The krill, in turn, are fed on by larger aquatic organisms and fish. Blue whales exclusively feed on krill.

The phytoplankton depend on macronutrient minerals and vitamin B in the waters to survive, which lead some scientists to support iron fertilization of the oceans by adding iron salts to increase their growth and decrease atmospheric carbon dioxide. However, concerns over manipulation of the ecosystem and the efficiency of such methods halted experimentation. Fertilizing could also encourage harmful algal blooms (HAB) which decrease the water’s oxygen to dangerously low levels. (source)

5 If you implode a bubble underwater with a soundwave, it emits flashes of light, and no one knows why. 

Also known as “sonoluminescence,” the effect was first accidentally discovered in 1934 by H. Frenzel and H. Schultes who were working on sonar. They put an ultrasound transducer in a tank of photographic developer fluid hoping to speed up the development process and instead noticed small dots on the film. Further experiments conducted to recreate and study the bubbles in stable conditions lead scientists to postulate that the temperature inside the bubble reached 12,000 to 20,000 kelvins.

In 2002, M. Brenner, S. Hilgenfeldt, and D. Lohse published a review that gives a detailed description of a process involving the presence and ionization of noble gasses, especially argon, resulting in a 160-picosecond flash. Though it is only one possible explanation, this mechanism is exploited in argon flash devices which give a very short and extremely intense flash and are used to photograph explosions or shock waves. Another explanation is the Casimir energy hypothesis which suggests that the flashes are generated by the vacuum inside the bubble just the way black holes emit Hawking radiation at an event horizon. (source)

6 If you dropped an object into an airless, frictionless tunnel between any two points on Earth, it would take it 42 minutes to reach the other side. 

The idea of an object accelerating inside a planet was first presented by British scientist Robert Hooke in a letter to Isaac Newton in the 17th century. In the 19th century, the Paris Academy of Sciences was presented with the concept of a gravity train, a train that could travel through a straight tunnel between two points on a planet just by using the planet’s gravitational acceleration and deceleration.

It is easy to assume that it would take longer to travel along a longer tunnel than it would if the distance between the two points is smaller. But, it actually takes the same amount of time no matter where the two points are on the sphere.

Assuming that the planet, or our planet Earth, is perfectly spherical and has uniform density, it takes about 2530.30 seconds or 42.2 minutes to travel between any two points along a straight tunnel. If you take into account the realistic distribution of density, then the time reduces to 38 minutes.

But, it is impossible to make such tunnels even if it’s possible to make them airless and frictionless because they would pass through the Earth’s mantle and core. There are, however, plans to design vacuum tube trains or vactrains such as Hyperloop to increase the speed of travel by reducing air resistance. (source)

7 If all the water on Earth were to be collected and made into a ball, its radius would just be 648 kilometers, less than half the radius of the Moon. 

Around 71% of Earth’s surface is covered with water, and the rest of 29% of the land is again filled with rivers, lakes, and other water bodies. However, all these water bodies are present in the Earth’s crust and are very shallow compared to the size of the Earth. To put that into perspective, the crust is between five to 70 kilometers thick while Earth’s mean radius is 6,371 kilometers.

Together, all the water on Earth is called the “hydrosphere” and it is an estimated 1,386 million cubic kilometers in volume. That is approximately 684 kilometers in radius which is half that of the Moon and slightly more than that of Rhea, the icy moon of Saturn. (1, 2)

8 The human brain cell can hold five times as much information as the Encyclopedia Britannica. 

The human brain is a complex, interconnected network of about one billion neurons with each neuron forming about a thousand connections with other neurons. Each neuron by itself can only store a limited, though not insignificant, amount of memories. But it’s the connections it makes with other neurons that increase the human brain’s capacity from mere gigabytes to an astounding 2.5 petabytes (a petabyte being a 1,000 terabytes). However, according to Don Cooper assistant professor at the University of Texas Southwestern Medical Center, individual nerve cells are more like a computer’s RAM and capable of storing information for up to a minute or longer. (1, 2)

9 All the helium in Earth’s atmosphere has escaped to space. The helium we have today is the result of radioactive alpha decay underground. 

At 5.2 parts per million in the atmosphere, helium on Earth is relatively rare and is a non-renewable resource since it escapes into space if released into the atmosphere. It was first discovered in 1868 by French astronomer Jules Janssen who noticed a yellow band, at first thought to be because of sodium, in the Sun’s chromosphere during a total solar eclipse in Guntur, India. In 1881, Italian physicist Luigi Palmieri found it in the material erupted from Mount Vesuvius and in 1895, and it was extracted from the mineral cleveite by Scottish chemist Sir William Ramsay.

In 1903, a drilling operation in Dexter, Kansas, uncovered a gas geyser that wouldn’t burn. Analysis by chemists revealed that 1.84% of the gas to be helium and thus providing a new source. This find helped the US gain monopoly over helium production and the Germans were forced to use hydrogen for their airships called Zeppelins, which is combustible.

The underground reserves are a result of the natural radioactive decay of elements such as thorium and uranium which emit alpha particles consisting of helium-4 nuclei. The concentrations of helium trapped in such natural gas reserves can be up to seven percent. Helium is also released in large quantities during volcanic activity. (source)

10 The farther away you look, the further back in time you see. 

It takes about 1.3 seconds for light reach Earth from the Moon and 8 minutes from the Sun. The farther away an object is, the longer it takes for light to reach our eyes. So, if an event were to happen a light-year away from us, it takes a year for the light to reach us, and what we see is something that happened a year ago. This is because, despite being the fastest thing in the universe, light has a limited speed.

Many of the stars and galaxies that we see now millions or billions of light-years away from us might not actually exist anymore because of this. A star’s life depends on the amount of fuel it has. In the millions or billions of years it takes for the light to travel to us, the star might have run out of fuel and perished. So, in a way, we do essentially see the past the farther into space we look. (source)