It's AumSum Time. How do some insects walk on water? They do not walk. They catwalk. No. Water has an unusual property. What is that? Each water molecule is attracted by other
molecules around it in all directions. But since the molecules at the surface have
no molecules above them. They get attracted inward more strongly. These inward forces of attraction create surface
tension. Thus, making the surface act like a stretched
membrane. Now, the weight of insects like water strider
and fishing spider is very less. So, the force that the insects' legs exert
on the stretched water surface is lesser. Than the surface tension. Also, as their legs are spread wide apart. Their weight gets further distributed among
all the legs. Hence, the insects' legs do not sink. And just create dimples on the stretched water
membrane. Helping it walk on water. Nuclear fusion. Why is nuclear fusion not used to generate
electricity? You really want to know the answer to this,
right? But wait. Before answering the question, let us understand
what is meant by nuclear fusion. When two lighter nuclei combine to form a
heavy nucleus. A large amount of energy is released. This process is called nuclear fusion. Where does this nuclear fusion take place? You think that it takes place in a laboratory? No, you are absolutely wrong. Nuclear fusion takes place in the sun. The nuclei of two hydrogen atoms join together
to form a heavy nucleus of helium. With the release of a large amount of energy. How do you think this energy reaches us? No. It does not reach us through power lines. Wait, I will tell you. The energy released after nuclear fusion reaches
us in the form of sunlight. Ultraviolet radiations, heat, etc. Hey. But we are already producing electricity with
the help of nuclear fission. So, why do we require nuclear fusion? For this, you need to first understand difference
between nuclear fusion and nuclear fission. As we already know, nuclear fusion is the
fusion of two lighter nuclei. With the release of a large amount of energy. The exact opposite process happens in nuclear
fission. Here, a heavier nucleus splits into two lighter
nuclei, releasing a large amount of energy. This process of fission is used in nuclear
power plants. Where a heavy nucleus of uranium is split
into lighter nuclei. The energy that is released in this is used
to generate electricity. However, there is a major disadvantage of
nuclear fission. Wondering what it is? The major disadvantage is that uranium is
a radioactive element. When uranium undergoes fission, it generates
radioactive waste along with energy. This radioactive waste is very harmful for
most lifeforms and the environment. Hence, we need to find a clean and safe source
of energy to generate electricity. What source would that be? Would it be nuclear fusion? You are right. Then why are we not harnessing the energy
of nuclear fusion to produce electricity? This is because, for nuclear fusion, two conditions
are required. They are high pressure and high temperature. Only when these conditions are met, can the
two nuclei travel at very high speeds. Resulting in collision. On earth, it is extremely difficult to create
such high pressure and temperature. Even if we are somehow able to create these
conditions. The question is how will we control them? As there are many questions unanswered and
unsolved. We have not yet succeeded in using nuclear
fusion in the production of electricity. Heat. Why is a laboratory thermometer not used to
check body temperature? You have got fever. Why don't you check your body temperature
using a thermometer? No. Please do not use a laboratory thermometer. You will not be able to get the correct reading. Why don't you try another one? This is called a clinical thermometer. A clinical thermometer is different from a
laboratory thermometer. Seems like you have made your choice. A clinical thermometer has a kink. When we check our body temperature, the kink
present in it prevents the mercury. From falling back down, thus helping the thermometer
to hold the temperature recorded by it. And giving us an accurate reading. Now, in a laboratory thermometer, this kink
is absent. This is because a laboratory thermometer is
meant to measures immediate temperature. Hence, after recording our body temperature,
until we check it, the mercury will fall. Thus, not giving us an accurate reading. Ultrasound. Why is ultrasound used in sonar? Hey. Looks like you are searching for a treasure
hidden in a sunken ship. Why don’t you use a sonar? It will emit ultrasounds and help you locate
the ship. You know what, I have a better idea. No. A music system will make ordinary sound. So, it is of no use. Do not fool me. I know that the music system is the right
choice. See, you are not able to find the ship. Now, will you use a sonar? Look, you easily found the ship. Do you know how a sonar could locate the sunken
ship? It was because of ultrasound. Ultrasounds are sounds having very high frequencies
which start from 20,000 Hertz. So, is ultrasound used in sonar because of
its high frequency? You are absolutely correct. Due to its high frequency, an ultrasound can
penetrate to a greater depth. Thus, helping us to locate the depth of the
sea, sunken ships, etc. But, I am not able to hear the ultrasound? It is because human beings can hear sound
frequencies from 20 Hertz to 20,000 Hertz. As ultrasounds have frequencies higher than
20,000 Hertz, we cannot hear them. Bad conductors of heat. Why are two thin blankets warmer than one
thick blanket? Because two chocolates are better than one. No. To understand this, we need to first learn
about bad conductors of heat. Bad conductors of heat are the materials which
do not allow heat. To easily flow through them. Air, wood and glass are some examples of bad
conductors of heat. In these examples, is our train conductor
included as well? Just listen. A thick blanket allows much of our body heat
to escape into the atmosphere. However, when we use two blankets one on top
of the other. Air gets trapped between them. This air being a bad conductor of heat, does
not allow our body heat. To easily flow into the atmosphere, thus keeping
us warm. Pathogens. Why do we get fever? So that we can take a holiday from work. No. Fever is a protective response of our body
to fight against pathogens. Such as bacteria, viruses and fungi. These pathogens cause diseases. Hence, when pathogens enter our body, the
immune cells such as white blood cells. Produce chemicals called pyrogens which are
released into the bloodstream. I thought like movies, they are released in
theaters. Please, pay attention. Hypothalamus, which is a small part of our
brain, regulates our body temperature. However, when these pyrogens reach the hypothalamus,
it starts to raise our body temperature. Thus, producing fever. Now, one of the reasons for producing this
fever is that many pathogens. Cannot survive at high temperatures. Thus, they die and we remain safe. Human tears. Why do onions make you cry? Because they cannot crack a joke. No. Onions consist of amino acid sulfoxides. When we cut an onion, millions of onions cells
rupture. Releasing the amino acid sulfoxides along
with some special enzymes. These special enzymes react with amino acid
sulfoxides. To form a chemical called Syn-propanethial-S-oxide. This chemical is volatile, that is, it easily
evaporates at normal temperature. Forming a gas. When this gas reaches our eyes, it reacts
with substance that keeps eyes lubricated. And forms mild sulfuric acid. What? An acid in my eyes. Absolutely. This sulfuric acid gives us a burning sensation. Now, in order to wash off this acid, our lacrimal
glands produce a disinfecting liquid. But when our eyes cannot hold any extra amount
of disinfecting liquid. It starts to fall down, making us cry. Joints. Why do knuckles pop? So that when we get bored we can pop them
for time pass. No. A knuckle is a joint in the finger where two
bones come together or connect. This joint is filled with a fluid called synovial
fluid. Synovial fluid is a viscous fluid containing
dissolved gases like oxygen and carbon dioxide. When bones move, the synovial fluid prevents
them from grinding against each other. It is so amazing. Indeed. When we stretch or bend our finger, the space
between the two bones increases. This causes the synovial fluid to stretch,
thus creating low pressure in it. Now, as gases are less soluble at low pressure. The dissolved gases in the synovial fluid
undissolve. Resulting in the formation of a bubble, which
we hear as the pop sound. Why do animals' eyes glow in the dark? Because they have hidden torches. No. Wait, I will explain. Our eyes have a layer called retina which
is made up of photoreceptors. When light enters our eyes, it hits the photoreceptors. Photoreceptors detect light, thus making it
possible to see. However, the light which does not hit the
photoreceptors remains undetected. Poor undetected light. Now, nocturnal animals like owls, need to
see better during the night. Hence, their eyes have another layer below
the retina called tapetum lucidum. Now, when light does not hit the photoreceptors,
it reaches the tapetum lucidum. This layer acts like a mirror. It reflects light back onto the photoreceptors. Thus, giving them a second chance to detect
light. Some of this reflected light also comes out
of the animal's eyes. Thus, making it seem that its eyes are glowing. What happens if a plane is struck by lightning? It will start glowing like a disco ball. No. Lightning is a massive flow of charge which
carries thousands of volts of electric current. Thus, it is extremely fatal for living beings. And can damage anything that comes in its
way. Yes, it is really terrifying. Now many times, airplanes get caught in a
heavy lightning storm. However, airplanes are designed to handle
the lightning strikes. The outer skin of most planes is primarily
made of aluminum. Aluminum is a good conductor of electricity. When lightning hits the airplane. The electric current travels through outer skin of the plane. It does not pass into the airplane. Eventually, it exits off through another extremity,
such as tail. Thus, the airplane and the passengers within
remain protected. Why cannot dogs eat chocolates? Because I would love to have all the chocolates
for myself. Alright. Now listen. Chocolates and other cocoa products contain
a toxic component called theobromine. The darker the chocolate, the more theobromine
and the more it is harmful. But I eat chocolates and I am completely fine. Our body quickly metabolizes the theobromine. Thus, it is not quite harmful for us. However, dogs process theobromine much more
slowly. So, it stays in their bodies for a longer
time, resulting in vomiting, diarrhea, etc. Moreover, if large quantities of chocolate
are ingested by the dog. Then the effects can be much more severe. The heart rate of dog might beat twice its
normal rate, increasing the blood flow. This can prove to be lethal to the dog. What is sleep paralysis? No idea. Sleep paralysis is a condition in which we
are conscious. But temporarily unable to move or speak. It can usually occur when we suddenly wake
up during REM sleep. What is REM sleep? Basically, there are four stages of sleep. One of them is Rapid eye movement sleep, that
is, REM sleep. In this stage, we dream. Researchers suggest that when we enter REM
sleep, two chemicals, glycine and GABA. ''Switch off'' the activity of cells in the
brain that allow our muscles to move. No. This is so bad. No. It is actually beneficial because paralyzed
muscles. Prevent us from enacting our dreams in reality
and getting hurt. However, sometimes we suddenly wake up during
REM sleep. But if glycine and GABA are still active,
we are temporarily unable to move. Even though we are conscious. This is called sleep paralysis. Why do newborn babies get jaundice? I do not know. Each red blood cell in our blood lives for
about 120 days. Once it gets old, it is broken down into smaller
components. One of them is bilirubin. Bilirubin is a yellowish waste compound. Hence, our liver removes the bilirubin from
our blood. Which is then excreted by the body through
intestines. However, if bilirubin is not removed, its
level in the blood starts to rise. And excess bilirubin begins to get deposited
in the body tissues. As a result, the skin and white areas of eyes
appear yellow, thus causing jaundice. Now, a newborn baby's liver is still developing. Thus, it cannot efficiently remove bilirubin
from blood, thus causing it jaundice. Usually, jaundice is normal in babies and
will disappear in some days as baby grows. However, if it does not disappear, we should
immediately consult a doctor. What is a mirage? An invisible cloak. No. Mirage is an illusion in which it appears
as if there is water on ground. On a hot day, the land heats the layers of
air closer to it. However, as we move higher, the layers of
air get relatively cooler. Thus, the hot lower layers of air near the
ground form rarer media. And cold upper layers form denser media. Now, when light coming from sky travels from
denser to rarer media. It bends more and more until it exceeds the
critical angle. That is, the angle beyond which light gets
reflected. This phenomenon is called total internal reflection. When this reflected light reaches our eyes,
they trace it backward as a straight line. Hence, the reflection of blue sky appears
on the ground. And our brain thinks that there is water,
thus causing a mirage. Why do we get eye bags? It is a sign indicating that we need to take
a long holiday. No. One of the main reasons for eye bags is aging. As we age, various changes take place in our
body. Yes, I get more attractive with age. Now listen. Our skin contains collagen and elastin. They keep our skin firm and elastic. In addition to this, we have fat tissue surrounding
our eyes for cushioning. But as we age, our skin produces less collagen
and elastin. Causing our skin to become loose. Also, the muscles and ligaments that hold
fat tissue in place begin to get loose. And the fat starts dropping down. This loose skin and fat make the area around
our eyes appear swollen. Giving us eye bags. Besides this, heredity, salt intake, smoking,
etc. May also contribute to formation of eye bags. Is gluten bad for you? Gluten is bad for everybody. As usual, you are wrong. Gluten is a combination of proteins found
in grains like wheat, barley and rye. Gluten makes dough sticky and gives pasta
its chewiness. Now, gluten is not usually harmful. But people having a digestive disorder called
celiac disease should not consume gluten. But why? When people having celiac disease eat gluten,
it triggers an autoimmune response. In this response, the immune cells attack
our own body tissues. Damaging the villi present in the small intestine. Thus, causing inflammation, diarrhea, fatigue,
etc. In addition to this, damaged villi will not
be able to absorb the required nutrients. Thus, causing weight loss, iron deficiency,
etc. Thus, people suffering from celiac disease. As well as those having gluten related allergies
should preferably have a gluten free diet. Why are sunsets red? Because sunsets are romantic. No. It is basically because of scattering of light
in the atmosphere. Our atmosphere is primarily composed of tiny
nitrogen and oxygen particles. Now usually, when sunlight comprising of seven
colors passes through the atmosphere. It hits the nitrogen and oxygen particles. These particles scatter blue and violet light
more. As compared to red, orange and other colored
lights. Hence, mostly bluish light enters our eyes,
thus making the sky to usually appear blue. However, during sunset, the sunlight must
pass through a greater distance. In the earth's atmosphere, causing it to pass
through more particles. As a result, most of the blue and violet light
get scattered before they reach our eyes. Due to this, the less scattered light like
red or orange reaches our eyes. Making the sunset appear red. Are Einstein's gravitational waves real? No. They are waves created by Titanic. As always, you are wrong. Gravity is the attractive force with which
two objects pull each other. However, Albert Einstein imagined gravity
as well as space and time a little differently. His theory of general relativity unified two
separate entities space and time. Into a single entity called spacetime. Spacetime can be considered as the fabric
of universe. Now, just like a heavy ball creates a curve
or distorts the trampoline. Mass of an object creates a curve in spacetime,
that is, in the fabric of universe. According to Einstein, this curve is gravity. This trampoline is amazing. First listen. Just like our hands create ripples in water,
moving objects create ripples in spacetime. These ripples are termed as gravitational
waves. Gravitational waves were directly observed
for the first time on September 14, 2015. By Laser Interferometer Gravitational Observatory
in the US. Why do we love chocolates? Chocolate is one of the most craved foods
in the world. It just melts in our mouth and tastes so good
that. Many of us are ready to eat them at any given
time. Now, one of the reasons why we love chocolates
is because. They contain a substance called anandamide. In Sanskrit, 'Ananda' means 'bliss'. Now, when we eat chocolates, anandamide present
in them. Binds to special receptors in the brain. Giving us bliss and joy, thus making us love
chocolates. Some chocolates also contain substances like
theobromine. It is thought that this theobromine makes
our brain produce anandamide by itself. Making sure that we feel blissful after eating
chocolates. In addition to this, most types of chocolates
contain sugar to make them taste sweet. Sugar activates the reward system in the brain. Due to which neurotransmitters like dopamine
are released. Dopamine gives us pleasure and makes us feel
good. As it makes us feel good, we tend to eat more
chocolates to get the same feeling. And thus, we get addicted to chocolates. Moreover, whether it is milk chocolate, white
chocolate or dark chocolate. There are numerous varieties to choose from. Also, there are dry fruits like raisins, almonds,
cashew nuts, etc. which we generally like. When these dry fruits are added to chocolates,
the desire to eat chocolates increases. Also, according to a study. It is observed
that salt suppresses bitterness and increases sweetness. Hence, while preparing desserts like chocolate
cakes, cookies, brownies, etc. A little salt is added to them, making the
desserts more inviting and tempting. Thus, we easily get attracted towards them. How tall can we grow? I can grow as big as the Eiffel Tower. Stop bluffing. Height is determined by a number of factors. One of them is our genes. We inherit our genes from our parents. Hence, these genes will make us grow approximately
as tall as our parents. In addition to this, factors like nutrition,
physical health, hormones, etc. Also affect our height. Now, if we grow taller than what we are at
present. Then we will not be able to support our body's
structure efficiently. For this, we would require much larger bones. Or they need to be made of much stronger material. In addition to this, if we were taller, the
amount of blood in our body would be more. Thus, making it hard for the heart to pump
so much blood. Besides this, the earth's gravity constantly
pulls us down. As a result, it prevents us from getting taller.
