My Science School

The denser a substance, the heavier it is for a given volume: this is why dense stones sink in water while air-filled buoys float. The fact that ice floats thus precisely means that it is less dense than liquid water. The reason is that water molecules in ice follow a geometrical structure in which the distance between two molecules is larger than their average distance in the liquid. At low temperature, when water becomes ice, the molecules move slowly enough to fit themselves into this structure.

But at higher temperature in the liquid, they move too fast to do so and often come closer to each other. As a consequence, water unusually takes more space in its solid form and ice is less dense than liquid water. You can observe that if you leave a water bottle in the freezer when the water freezes, it will need more space. Actually, it might even break the bottle, so be careful!

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Charles Darwin, in full Charles Robert Darwin, (born February 12, 1809, Shrewsbury, Shropshire, England—died April 19, 1882, Downe, Kent), English naturalist whose scientific theory of evolution by natural selection became the foundation of modern evolutionary studies. An affable country gentleman, Darwin at first shocked religious Victorian society by suggesting that animals and humans shared a common ancestry. However, his nonreligious biology appealed to the rising class of professional scientists, and by the time of his death evolutionary imagery had spread through all of science, literature, and politics. Darwin, himself an agnostic, was accorded the ultimate British accolade of burial in Westminster Abbey, London.

Darwin formulated his bold theory in private in 1837–39, after returning from a voyage around the world aboard HMS Beagle, but it was not until two decades later that he finally gave it full public expression in On the Origin of Species (1859), a book that has deeply influenced modern Western society and thought.

Darwin's exploratory survey on the H.M.S. Beagle had brought him into contact with a wide variety of living organisms and fossils. The adaptations he saw in the finches and tortoises on the Galapagos Islands struck him particularly acutely. Darwin concluded that species change through natural selection, or - to use Wallace's phrase - through "the survival of the fittest" in a given environment.

Darwin's book immediately attracted attention and controversy, not only from the scientific community, but also from the general public, who were ignited by the social and religious implications of the theory. Darwin eventually produced six editions of this book.

In time, a growing understanding of genetics and of the fact that genes inherited from both parents remain distinct entities - even if the characteristics of parents appear to blend in their children - explained how natural selection could work and helped vindicate Darwin's proposal.

Credit : Britannica 

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The Principles of Biology by Herbert Spencer (1864) looked at biology in terms of themes, such as Function, Adaptation and Variation. In this book Spencer introduced the expression ‘survival of the fittest’, in the sense of ‘the most appropriate to its environment’. 

Spencer was a polymath whose work includes writings on religion, economics, literature, biology, sociology, and political theory. He built an understanding of evolution as the progressive development of all creation from simple forms based on homogeneity towards an integrated equilibrium of differentiated forms, against the theories of Darwin. It also worked against the idea that everything moves towards homogeneity rather than heterogeneity (the second law of thermodynamics). 

Spencer, against the thinking of Darwin, incorporated into his thinking Lamarckian models – the idea that acquired characteristics could be inherited. These models explained the extraordinarily accelerated development of the human species. 

Spencer has been credited with the idea that Darwinian evolution provides a natural justification for the notion that ‘might is right’. In fact he believed that the model for economic competition could be found in competition for resources in nature; but competition could be managed for the good of society, so long as it did not lead to increased power for the state. If private charity led to the support for an idle underclass then it was a failure, an idea that when combined with population management, tends towards support for eugenics.

Credit : British Library

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Cambrian explosion, the unparalleled emergence of organisms between 541 million and approximately 530 million years ago at the beginning of the Cambrian Period. The event was characterized by the appearance of many of the major phyla (between 20 and 35) that make up modern animal life. Many other phyla also evolved during this time, the great majority of which became extinct during the following 50 to 100 million years. Ironically, many of the most successful modern phyla (including the chordates, which encompass all vertebrates) are rare elements in Cambrian assemblages; phyla that include the arthropods and sponges contained the most numerically dominant taxa (taxonomic groups) during the Cambrian, and those were the taxa that became extinct.

The beginning of the Cambrian Period is marked by the evolution of hard body parts such as calcium carbonate shells. These body parts fossilize more easily than soft tissues, and thus the fossil record becomes much more complete after their appearance. Many lineages of animals independently evolved hard parts at about the same time. The reasons for this are still debated, but a leading theory is that the amount of oxygen in the atmosphere had finally reached levels that allowed large, complex animals to exist. Oxygen levels may also have facilitated the metabolic processes that produce collagen, a protein building block that is the basis for hard structures in the body.

Other major changes that occurred in the Early Cambrian (541 to 510 million years ago) include the development of animal species that burrowed into the sediments of the seafloor, rather than lying on top of it, and the evolution of the first carbonate reefs, which were built by spongelike animals called archaeocyathids.

Credit : Britannica 

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Even though Mercury is the closest planet to the Sun, Venus is the hottest planet in our solar system. This is because Mercury has almost no atmosphere, while Venus has a very thick atmosphere. This causes all the heat to be radiated back into space on Mercury. However, the heat is trapped on Venus, with the average temperature being 462°C.

The degree of hotness of a planet does not depend on as much on closeness to the Sun as on its atmosphere. Carbon dioxide has the tendency to absorb heat which in turn increases the temperature.

Mercury's atmosphere does not contain carbon dioxide (because of which all the heat is returned to space). Venus contains a high percentage of carbon dioxide due to which it is hottest planet.

In ancient times, Venus was often thought to be two different stars, the evening star and the morning star — that is, the ones that first appeared at sunset and sunrise. In Latin, they were respectively known as Vesper and Lucifer. In Christian times, Lucifer, or "light-bringer," became known as the name of Satan before his fall. However, further observations of Venus in the space age show a very hellish environment. This makes Venus a very difficult planet to observe from up close, because spacecraft do not survive long on its surface.

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Planet Mercury actually has no moons. Up first are Mercury and Venus. Neither of them has a moon.

Because Mercury is so close to the Sun and its gravity, it wouldn’t be able to hold on to its own moon. Any moon would most likely crash into Mercury or maybe go into orbit around the Sun and eventually get pulled into it.

If moons are such a common feature in the Solar System, why is it that Mercury has none? Yes, if one were to ask how many satellites the planet closest to our Sun has, that would be the short answer. But answering it more thoroughly requires that we examine the process through which other planets acquired their moons, and seeing how these apply (or fail to apply) to Mercury.

To break it all down, there are three ways in which a body can acquire a natural satellite. These causes have been determined thanks to many decades of astronomers and physicists studying the various moons of the Solar System, and learning about their orbits and compositions. As a result, our scientists have a good idea of where these satellites came from and how they came to orbit their respective planets.

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Mercury, Latin Mercurius, in Roman religion, god of shopkeepers and merchants, travelers and transporters of goods, and thieves and tricksters. He is commonly identified with the Greek Hermes, the fleet-footed messenger of the gods.

The cult of Mercury is ancient, and tradition has it that his temple on the Aventine Hill in Rome was dedicated in 495 BCE. There Mercury was associated with Maia, who became identified as his mother through her association with the Greek Maia, one of the Pleiades, who was the mother of Hermes by Zeus; likewise, because of that Greek connection, Mercury was considered the son of Jupiter. Both Mercury and Maia were honoured in the Mercuralia festival on May 15, the dedication day of Mercury’s temple on the Aventine.

Mercury is sometimes represented as holding a purse, symbolic of his business functions. Artists, like followers of Roman religion themselves, freely borrowed the attributes of Hermes and portrayed Mercury also wearing winged sandals or a winged cap and carrying a caduceus (staff).

Credit : Britannica 

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All of the planets in our Solar System have had a lot of craters. This was especially true in the past when there were many more asteroids traveling in our solar system than there are today. On planets like Venus, Earth, and Mars, we do not see as many craters because most of them have been eroded away by wind, rain, volcanic activity, and other forces. On the giant gas planets, Jupiter, Saturn, Uranus, and Neptune, we do not see any craters because there is no visible solid surface for the meteors to hit. On Mercury, where there is no atmosphere, there is no weather to erode away the craters, so most of the craters are still visible.

Craters are the most widespread landforms in the solar system. Craters are found on all of the terrestrial planets—Mercury, Venus, Earth and Mars. The surfaces of asteroids and the rocky, ice covered moons of the outer gas planets are cratered as well. The craters left by impacting objects can reveal information about the age of a planet's surface and the nature and composition of the planet's surface at the time the crater was formed.

Impact craters dominate the surfaces of Mercury and the Earth's Moon. Both bodies lack liquid water on their surfaces that would erode impact craters over time. They also lack an atmosphere which, on planets like the Earth and Venus, could disintegrate meteoroids before they impact the surface. However, old craters can be eroded by new impact events. Mercury and the Moon have very old surfaces. One of the youngest large craters on the Moon is Tycho, which was formed about 109 million years ago.

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The smallest planet in our solar system and nearest to the Sun, Mercury is only slightly larger than Earth's Moon.

From the surface of Mercury, the Sun would appear more than three times as large as it does when viewed from Earth, and the sunlight would be as much as seven times brighter. Despite its proximity to the Sun, Mercury is not the hottest planet in our solar system – that title belongs to nearby Venus, thanks to its dense atmosphere.

Because of Mercury's elliptical – egg-shaped – orbit, and sluggish rotation, the Sun appears to rise briefly, set, and rise again from some parts of the planet's surface. The same thing happens in reverse at sunset.

Credit : NASA Science 

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A retrovirus is a virus that uses RNA as its genetic material. When a retrovirus infects a cell, it makes a DNA copy of its genome that is inserted into the DNA of the host cell. There are a variety of different retroviruses that cause human diseases such as some forms of cancer and AIDS.

Retroviruses cause tumour growth and certain cancers in animals and are associated with slow infections of animals, such as equine infectious anemia. In humans, a retrovirus known as human T-cell lymphotropic virus type 1 (HTLV-1) causes a form of cancer called adult T-cell leukemia (ATL). It can also cause a neurodegenerative condition known as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). A closely related virus named HTLV-2 is associated with relatively mild neurological disorders but has not been identified as a causative agent of human disease. As many as 20 million people worldwide are thought to be infected with HTLVs, but only a small percentage of infected individuals actually develop ATL or HAM/TSP. The retrovirus known as human immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome (AIDS) in humans. HIV is closely related to simian immunodeficiency virus (SIV), a retrovirus found in chimpanzees and gorillas.

So-called endogenous retroviruses (ERVs) are persistent features of the genomes of many animals. ERVs consist of the genetic material of extinct, or “fossil,” viruses, the genomic constitution of which is similar to that of extant retroviruses. Human ERVs (HERVs) have become distributed within human DNA over the course of evolution. They are passed from one generation to the next and make up an estimated 1 to nearly 5 percent of the human genome. HERVs are suspected of having influenced the evolution of certain elements of the human genome. They also have been implicated in certain human diseases, including multiple sclerosis.

HTLV-1 was the first human retrovirus to be discovered, having been detected and isolated in 1979 by American virologist Robert C. Gallo and colleagues. HIV was first isolated in 1983.

Credit : Britannica 

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Flossie Wong-Staal, a molecular virologist most famous for co-discovering and first cloning the human immunodeficiency virus (HIV) that causes AIDS, died July 8 of complications from pneumonia in La Jolla, California, at age 73.

Wong-Staal arrived at the National Cancer Institute (NCI) in 1973 as a postdoctoral researcher in the lab of fellow virologist Robert Gallo, where she quickly became an essential contributor to the team’s work studying retroviruses. Together, Gallo and Wong-Staal published more than 100 papers in 20 years, according to an article by the NCI, and a 1990 article in The Scientist credits her as being the most-cited woman in science during the 1980s, earning 7,772 citations in academic journals. Wong-Staal was inducted into the National Women’s Hall of Fame last year for her contributions to the field.

During her time in Gallo’s lab, Wong-Staal was part of the group that identified the first human retrovirus, human T-cell leukemia virus type 1 (HTLV-1), and showed that it could cause cancer. While it was already known that retroviruses replicated by inserting their genetic material directly into the genome of their hosts, scientists of the day were skeptical that these viruses could cause cancer in humans. “At the time, the dogma was that [human tumor viruses] did not exist,” Wong-Staal said in a 1997 oral history, adding that the lab was often criticized in its search for “rumor viruses.”  

In the early 1980s, when AIDS cases first began appearing in alarming numbers, Wong-Staal was uniquely poised to study the emerging epidemic—HIV, the virus that causes the disease, turned out to be a retrovirus. A team led by Gallo shared the co-discovery of HIV with the French scientist Luc Montagnier, and Wong-Staal provided the molecular evidence needed as proof. In 1985, she would become the first person to clone HIV and begin studying the functions of its genes, a necessary step towards developing eventual treatments.

Credit : Scientist 

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Flossie Wong-Staal was a Chinese-American virologist and molecular biologist who cloned human immunodeficiency virus (HM) for the first time. She determined the function of its genes, a significant step in our understanding and treatment of HIV/AIDS. Flossie Wong-Staal (original name Yee Ching Wong) was born in 1947 in China. She attended an all-girls Catholic school in Hong Kong, where she excelled academically. Her teachers and parents encouraged her to take up science, although her interest lay in literature. However, she pursued science and began to love it.

In Wong-Staal went to the United States to study bacteriology at the University of Los Angeles (UCLA), She earned her Ph.D. in molecular biology from UCLA in 1972.

Research into retroviruses In 1973, she began her research into retroviruses along with Robert Gallo at the National Cancer Institute. Retroviruses are a group of viruses that infect their victims by inserting their genetic material into the host's DNA. Wong-Staal was part of the group that identified the first human retrovirus, human T-cell leukemia virus type 1 (HTLV-1). The team showed that the retrovirus could cause cancer, a stance long dismissed by the research community.

In the early 1980s, when AIDS cases first began appearing in the United States, Wong-Staal and Gallo quickly set about finding the cause and they succeeded in 1983. The duo, along with Luc Montagnier in France, simultaneously discovered that HIV, a retrovirus, was the cause of AIDS. In 1985, Wong-Staal became the first researcher to clone HIV. It led to the first genetic mapping of the virus, which aided in the development of blood tests for HIV.

Other scientific contributions Wong-Staal's research into the Tat protein within the viral strain HIV-1 led to the development of new treatments for Kaposi's sarcoma, a type of skin lesion, affecting HIV/AIDS patients.

In 1990, Wong-Staal joined the University of California San Diego, where she led the Center for AIDS Research and investigated gene therapy as a treatment for HIV/AIDS.

Wong Staal died of pneumonia (not related to coronavirus) in 2020 at the age of 73.

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What you need:

• A glass bottle
• A straw
• Modelling clay
• Water
• Food colour
• A container
• A glove

What to do:

1. Add a few drops of food colouring into the empty bottle.

2. Pour cold tap water over it, filling the bottle right up to its neck.

3. Now, place a straw into the bottle. Holding most of its length out of the bottle (the other end should be in the coloured water though), pack the modelling clay around the straw, sealing the bottle's mouth.

4. Fill the container with hot water. Place the glass bottle into the container. What happens?

5. Wear the glove and transfer the bottle to a container containing cold water.

What happens:

When the bottle is placed in hot water, the water level in the straw goes up. When the bottle is in cold water, the water level in the straw goes down again. This indicates that the level of water reflects the change in temperature, just like a thermometer.

Why?

When water heats up, it expands. That means that its molecules spread out and the space between them increases. Because the bottle is sealed and the straw is the only opening, the water expands and moves into the straw. The more it is heated, the more water expands and the level in the straw rises. Similarly, when the water cools down, it contracts causing its molecules to draw closer together. This causes the water level in the straw to fall.

If you draw a makeshift scale on the straw using a marker (refer a normal thermometer for how the scale should look), you can actually monitor the temperature change with respect to the expansion and contraction of water.

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What you need:

• A spool
• A large rubber band
• A toothpick
• An unsharpened pencil
• Tape
• Scissors
• A metal washer (available at a hardware store)

What to do:

1. Thread the rubber band through the hollow centre of the spool. You should be able to see a bit of the band peeking out from both ends of the spool.

2. Break the toothpick so that it is just smaller than the diameter of the spool.

3. Push the toothpick through the rubber band at one end. Pull out and tighten the other end of the rubber band so that the toothpick is held tight against the spool.

4. Cut a small piece of tape and stick it over the toothpick to hold it in place.

5. On the other end of the spool, thread the rubber band through the washer. Push the washer in so that it rests against the spool.

6. Insert a quarter of the pencil through the loop of the rubber band. Wind up the band tightly using the pencil.

7. Set the spool down on its side on a table or on the floor and release the pencil.

What happens:

The spool whirls off like a wheel, pencil and all!

Why?

When you twirl the rubber band with the pencil, you are winding it up to store potential energy. The more you wind the band, the more energy it stores. Potential energy is the energy an object holds that can be used to do some work in the future. Simply put, it has the potential to do work based on its position, or its internal stresses or its electrical charge, etc.

It is the law of the world that energy cannot be created or destroyed; it can only change form. When you place the spool on the table and release the pencil, it starts to unwind. The potential energy of the band converts to kinetic energy. Kinetic energy is the energy that a body has due to motion. That's what gets the spool rolling.

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