Category Archives: Physics

The hottest place in the Universe exists on Earth

The hottest place in the Universe exists here on Earth, like the coldest place in the Universe. Both these extreme temperatures are not natural, they are human-made. The coldest temperature was achieved in the German physicist and professor of physics Wolfgang Ketterle’s laboratory at the Massachusetts Institute of Technology (MIT). The hottest temperature, also recognized by the Guinness Book of World Records, was achieved at CERN’s Large Hadron Collider (LHC).

On 13 August 2012 scientists at CERN’s Large Hadron Collider, Geneva, Switzerland, announced that they had achieved temperatures of over 5 trillion K and perhaps as high as 5.5 trillion K (more than 9.9 trillion °F). The team had been using the ALICE experiment to smash together lead ions at 99% of the speed of light to create a quark-gluon plasma – an exotic state of matter believed to have filled the universe just after the Big Bang.

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The coldest place in the Universe exists on Earth

It may sound strange, but the coldest place in the Universe is not anywhere in the vast, cold outer space – it exists here on Earth. Well, it is not actually a natural place you can come across. It is in a laboratory in M.I.T. (Massachusetts Institute of Technology).

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LIGO detects gravitational waves from neutron star merger

Carl Sagan’s famous quote says “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff.” In that famous quote, Sagan makes reference to the whole universe started off with hydrogen and helium, all stars produce helium, and then stars over a certain mass threshold produce carbon, nitrogen, oxygen and lots of heavier elements – which are also the source of the life. The star stuff is inside us – every living thing on Earth.

But, even stars aren’t powerful enough to create heavy elements like silver, gold, and cesium. Since the 1950s, scientists have wondered: where do most of the elements in the periodic table come from?

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Why do we see only one side of the Moon?

You have probably heard references been made to the “dark side” of the Moon – there’s even a Pink Floyd album with that name. But, in fact, there’s no “dark side” of the moon. Because it is not illuminated by the Earth, it is illuminated by the Sun. All the surface of the moon lit by the Sun as the Moon rotates. But, yes, we see only one side of the moon and here’s why.

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Why astronauts float in space

We see images and videos from the International Space Station (ISS) where astronauts floating in the space freely. That’s because they’re in the space, so there is no gravitational force of Earth there, right?


The International Space Station is in Low Earth OrbitSee notes 1 with an altitude of between 330 and 435 km (205 and 270 mi). It is so close to the Earth that on a clear day easily visible to the naked eye from the ground as it is the third brightest object in the sky (NASA has actually launched a new interactive map at its Spot the Station web site). At that altitude, the Earth’s gravity is about 90 percent of what it is on the planet’s surface – still pretty strong, right? To reduce the gravity of the Earth by a factor of one million, one needs to be at a distance of 6 million kilometers (around 3,728,227 miles) from the Earth – more than fifteen times the distance between the Earth and Moon.

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How Earth Could Die – 8 Horrible Ways

Now we’re living on a warm, hospitable planet. As Carl Sagan has said “That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives.” We, humans, are the unquestionable rulers of our little oasis in a hostile universe. But all things must pass. The life on Earth, even the planet itself, won’t last forever. What’s more, the humans may go extinct before our planet (and probably before the life on it) dies out. Here some possible (and horrible) ways how planet Earth could die.

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How Eratosthenes calculated the Earth’s circumference

In 240 BC, the Greek astronomer, geographer, mathematician, music theorist and librarian Eratosthenes of Cyrene (c. 276 BC – c. 195/194 BC) calculated the circumference of the Earth without even leaving Egypt. Here’s how:

Eratosthenes knew that at local noon on the summer solstice (at the time of the longest day, about 21 June in the northern hemisphere) in Syene (modern Aswan, Egypt), the Sun was directly overhead – Syene was in fact slightly north of the tropic, though (1). Local noon is – technically when the sub-solar point is somewhere over your meridian, it’s noon for you. So, on that day, Syene is the sub-solar point of Earth (the sub-solar point on a planet is where its sun is perceived to be directly overhead). To learn more about the local noon and the subsolar point, see the article titled “How Earth Moves“.

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Are we the first?

In 1950, the Italian physicist Enrico Fermi was chatting with his colleagues at the Los Alamos National Laboratory(1). They talked about the recent rise in UFO reports, then the conversation shifted to other subjects. But during the lunch, Fermi suddenly asked: “Where is everybody?”. He was talking about the extraterrestrial life, especially intelligent life. He made some calculations on the probability of Earth-like planets, the beginning of life, the probability of intelligent life and high technology and concluded that we ought to have been visited long ago and many times over.

But, there is no reliable evidence aliens have visited Earth and we have observed no intelligent extraterrestrial life with current technology nor has SETI found any transmissions from other civilizations. The Universe, apart from the Earth, seems “dead”.

So, where is everybody?

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Your Life On Earth (presented by BBC)

A nice interactive webpage by the BBC – The British Broadcasting Corporation: how you and the world have changed since you were born? You’re simply entering your birth date, gender, and height; selecting units (metric or imperial/US) and then watching how our planet (and you) has changed in your lifetime.

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