Name: What is a Black Hole? | #aumsum
Uploaded: 2019-04-10T09:07:34.000Z
Duration: 5 min 24 s
Description: Usually, when a star is alive, the inward force of gravity is exactly balanced at each point by the outward force created by hot gases and radiation. These inward...

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The inward force of gravity is exactly balanced at each point by the outward force created by hot gases and radiation.

These inward and outward forces maintain balance and hold the star together.

However, when the star runs out of fuel, there are no hot gases and radiation.

Hence, there is no outward force to balance the inward pull of gravity and thus, the star begins to die.

The star's core begins to collapse under its
own gravity.

This collapse causes the outer layers to blow apart in a huge explosion called a supernova.

Now, it is estimated that if a star has at
least 20 times more mass than our sun.

Then the star collapses to form a black hole.

The surface or boundary of a black hole is
called event horizon.

Nothing can escape from within the event horizon of a black hole, not even light.

Eye boogers generally contain oil, dust, germs, etc.

They are formed from the tear film on our
eyes.

The tear film mainly consists of three layers.

Mucin layer, aqueous layer and lipid or oily layer.

Together, these layers moisturize our eyes.

They also trap dust and germs which are removed while blinking.

If there is any dust or germ, it gets discarded along with some tear film through the tear duct into the nasal cavity.

But while sleeping, since we don't blink.

The tear film, dust and germs get collected in the inner corners of our eyes and start to dry out.

Placebo in Latin means 'I shall please' and
this is what placebos do.

Placebos are inactive sugar pills, injections, etc. that look like real medications or treatments.

In most cases, they relieve pain and make us feel better, even though they are not actual medicines.

This effect of placebos on our body is called the placebo effect.

Now, one of the reasons why placebos are effective is that when we take them.

Our mind perceives placebos as real medications.

Hence, our brain reacts to the placebo in a manner which is similar to when we take real medications.

Thus, our brain releases natural painkillers
like endorphins that help relieve pain.

In addition to this, it also decreases the production of stress hormones, thus making us feel better.

Our ability to perceive taste is affected
by a few factors such as humidity, air pressure, etc.

In an airplane, the humidity is less as compared to that on the ground.

This makes the air in the airplane quite dry.

Also, to maintain the air pressure inside and outside the airplane, the air pressure inside it is decreased.

Decreased air pressure and dry air, dries
our nose and mouth.

Now, smell of food helps us to understand
the flavor and ingredients of the food.

Thus, the food which we cannot smell properly appears unappealing.

Also, dry mouth reduces the sensitivity of
our taste buds.

As a result, we cannot perceive the taste
of food properly.

Why should we not overwater potted plants?

It's because the water will overflow and make the floor dirty.

Leaves of a plant take in oxygen from the
air present in the atmosphere.

While, the roots, being buried in the soil, take in oxygen from the air present in tiny spaces of the soil.

When we overwater a potted plant, the air
in the tiny spaces gets replaced by water.

So, do the roots know how to swim in water?

As air gets replaced by water, the roots do not get sufficient oxygen to breathe and they begin to rot.

This may adversely affect the growth of the plant.

Thus, we should always try to supply adequate water to the potted plants and not overwater them.