Helium has two known stable isotopes – 3 He and 4 He. The abundance of helium-3 and helium-4 corresponds to 0.0002% and 99.9998% respectively. This difference in abundances can be observed in the Earth’s atmosphere, where the ratio of 4 He atoms to 3 He atoms is approximately 1000000:1. Physical Properties of Helium. Definition of helium-4 in the Definitions.net dictionary. Meaning of helium-4. What does helium-4 mean? Information and translations of helium-4 in the most comprehensive dictionary definitions resource on. The Helium 4 is the most advanced kite in our range. High-performance foilborders, surfers, travelers, and freeriders that want to get out in lighter wind conditions or who want a light and responsive kite will find the new Helium exceeding their expectations. Helium is used by: Core Technologies. The People's Network is made possible through sophisticated, open-source technologies that aim to create a truly decentralized and trust-less model for building wireless infrastructure. Helium is used by: Core Technologies. The People's Network is made possible through sophisticated, open-source technologies that aim to create a truly decentralized and trust-less model for building wireless infrastructure.

Yellowstone National Park’s geysers, hot springs, fumaroles and other hydrothermal features spew out a collection of gases from deep within the Earth—steam, carbon dioxide, methane, neon, argon and helium. There’s not enough of that last one, helium, for the park to start selling balloons or for visitors to sound like chipmunks, but there’s plenty for scientists to study.

Helium can bubble out of volcanic rocks that drive hydrothermal activity, but that’s not where most of Yellowstone’s helium is coming from, it seems. The park’s gas originates deep in rocks where it’s been stored for hundreds of millions of years, U.S. Geological Survey scientists report today in Nature.

Helium is the second-most abundant element in the universe—it’s formed by the nuclear fusion of hydrogen atoms, a process that powers stars—but it’s pretty rare here on Earth. Lucky for birthday-party goers and clowns (and modern medicine), helium can be extracted from reserves of natural gas underground.

Helium on Earth can be found in two main forms: Nearly all occurs as helium-4 (named thus because it has two protons and two neutrons), which can be produced during the radioactive decay of heavy elements such as uranium. A tiny fraction (about one in a million) occurs as helium-3 (two protons and one neutron), most of which has been present on Earth since the planet’s formation and is a vestige of material that originally formed the planet.

The ratio of helium-3 to helium-4, though, slightly varies and scientists can actually use that ratio to determine the approximate source of any helium they find. Uranium and other heavy elements are more incompatible with minerals found in the Earth's mantle, so these elements filter up to the crust, where their decay produces helium-4. Mantle materials, which contain less of these heavy radioactive elements, don't produce as much helium-4, so the helium present there is mostly in the form of helium-3.

The hydrothermal system at Yellowstone National Park has a relatively high amount of helium-3, and scientists consider this to be evidence that the Yellowstone hotspot originates deep within the mantle and has a relatively straight path up.

But it seems that the helium-4 has a more complicated journey to the surface. Researchers from the USGS have been collecting gas samples from across Yellowstone for a decade and performing chemical and isotopic analyses of the helium, carbon dioxide and other gases in those samples. The amount of helium-4 that’s being emitted in Yellowstone, they found, exceeds by several orders of magnitude the average amount they'd expect to find elsewhere.

Most of Yellowstone’s helium-4 is at least hundreds of millions—perhaps even billions—of years old, the scientists calculated. Given the amount of gas present, scientists conclude that it probably comes from rocks within very ancient crust known to be buried nearby. This super-old pocket of crust, from the Archaean eon, was formed more than 2.5 billion years ago and contains uranium and other radioactive materials that have been steadily decaying. That would have allowed high concentrations of helium-4 to build up underground. Then about two million years ago, the Yellowstone hotspot penetrated these ancient rocks, some of the oldest on the planet, and began releasing the helium-4 stored there along with helium-3 brought up from the mantle.

This discovery probably qualifies as “kind of interesting” for any Yellowstone fans, but for scientists, there might be more important implications. Helium and other noble gases are used to estimate groundwater residence times—for example, scientists assume that the more helium-4 present in water, the longer that water has been sitting in the rocks surrounding it.

But the study of helium at Yellowstone shows that some of these assumptions—specifically helium-4 produced by the steady decay of elements found only within the rocks and sediments of the local aquifer—aren’t quite right. Helium can suddenly come into a system from unexpected places—a pocket of ancient rock, for instance, or an magma source—so the dates in past calculations, particularly those from aquifers in volcanic regions or near earthquake faults, might be way off because of that extra helium.

Scientists, though, are used to dealing with new data that changes long-held theories; that’s the nature of science, after all. Residents of the Yellowstone area, however, probably wish researchers would just hurry up and figure out whether or not the supervolcano that’s simmering below them and last erupted 640,000 years ago is going to blow again anytime soon.

When things come to the quantum world, common sense does not work at all. One thing that bolsters the above statement is superfluid helium-4. It has properties that are completely absurd and does not make sense at all.

In this article

• Properties of Superfluid Helium-4

Superfluid Helium-4

Superfluid helium-4 is the liquid state of helium-4, isotopic helium with 2 neutrons and 2 protons, at a temperature below 2.18 Kelvin (more than 270-degree centigrade below zero) and normal pressure. We know that any substance liquefies and finally solidifies on cooling. Helium-4 also liquefies on cooling. But, when we cool helium-4 to a temperature below 2.18 Kelvin, its atom attains a state called Bose-Einstein Condensate (BEC), also called the fifth state of matterand shows a completely different property.

BEC is a state in which all the particles in a system are in the same quantum state, like all the tenants of a building gathering in a ground floor. In this state, all these particles behave like one. This behaviour gives rise to some amazing properties.

Properties of Superfluid Helium-4

Superfluid helium-4 is named superfluid because of its properties which are actually super. This state is analogous to superconductivity, in which the resistance becomes zero whereas in this case viscosity becomes zero. Owing to the amazing state, there are properties which ordinary liquid don’t have.

Ability to Resist Solidification at Atmospheric Pressure

We normally think that when we cool something it solidifies. Water solidifies at 0 degree Celsius, even hydrogen, the lightest matter, solidifies at 259 degree Celsius but it does not work for helium – 4 at normal pressure. Helium – 4 is the only matter that resists solidification at absolute zero at normal pressure.

This property is due to the noble and light nature of helium-4. So, it is almost impossible to confine helium atoms and make them immobile (rigid), which is the case in solid objects.

Zero Viscosity – Flowing Through the Smallest Pores

Just like zero resistance in case of superconductivity, superfluids have zero viscosity. Viscosity is liquid’s resistance to deformation, the frictional force between two liquid layers. Glycerine has high viscosity than water so that an iron ball falls faster in water than in glycerine due to low viscosity, low friction.

Due to this property, it can pass through the smallest pores possible. It can easily leak through non-glazed ceramic objects which are solid and can hold other liquids without leaking. For instance, if you are passing water through a net with small holes, it does not pass smoothly, water gathers at middle and falls but with superfluids the passage is smooth.

There is no such friction between the layers because all the atoms are in a single state and they are not sliding over one another. Helium-4 acts as a Boson rather than Fermion due to presence of paired particles. And Bosons can occupy a single state, making all the atoms as one single system and giving rise to superfluidity. They all superimpose and give rise to a single state. In such case there is no sliding over one another, they are all acting as one. There is absolute perfection.

Climbing Walls, Defying Gravity

Helium 4202

Liquid helium-4 can climb walls of the container. Generally, liquids can climb walls of the container to some extent due to their surface tension. Viscosity resists them to climb further and in vessels with the broad surface, the liquid cannot climb the walls. But, liquid helium-4 can climb walls of its container against gravity. Its motion is only limited by a critical velocity which is large enough. It also shows a fountain effect, rising through the walls like a fountain with a pressure of 0.692 bar.

Mass Of Helium 4

Why Not Helium-3 but Helium-4?

Helium 4 Isotope

Another isotopic helium is helium-3. It does not show superfluid behaviour in such temperature, it requires a lot smaller temperature. This is because helium-4 has bosonic nature while helium-3 is a fermion. Hence, helium-4 can transit to BEC state while Helium-3 cannot. For it to obtain such minimum energy state, the temperature must be very very close to absolute zero.