The Universe

Pic: New Scientist

Birth of Universe

Scientists define the Universe as absolutely everything that physically exists. But the Universe has not always existed. It is believed that the Universe was created by the Big Bang, when it started to grow from a tiny point that contained all the matter and energy.

What was there before the Universe?

No one knows. Some people think there was an unimaginable ocean, beyond space and time, of potential universe continually bursting into life or failing. Our succeeded.

What was the Universe like at the beginning?

The early universe was very small, but it contained all the matter and energy in the Universe today. It was a dense and chaotic soup of tiny particles and forces. But this original Universe lasted only a split second - just three trillionths of a trillionths of a trillionths of a second.

Can we see the Big Bang?

Astronomer can see the galaxies still hurting away from the Big Bang in all directions. They can also see the afterglow - low-level microwave radiation coming at us from all over the sky, called background radiation.

What is the Big Bang?

In the beginning, all the Universe was squeezed into an unimaginably small, hot, dense ball. The Big Bang was when this suddenly began to swell explosively, allowing first energy and matter, then atoms, gas clouds and galaxies to form. The Universe has been swelling ever since.

How do we know what the early Universe was like?

Machines called colliders and particles accelerators can recreate conditions in the early Universe by using magnets to accelerate particles to astonishing speeds and then crashing them together.

'New Galaxy: It was started

to form

13.5 billion years ago.'

How hot was the Big Bang?

As the Universe grew from smaller than an atom to the size of a football, it cooled from infinity to ten billion billion billion°C.

Growing Universe

The Universe has continued to expand ever since the Big Bang. Scientists are not sure if it will carry on growing for ever, beyond what we can possibly observe, or whether it will eventually come to a stop and end in a Big Crunch.

How long will the Universe last?

It depends how much matter it contains. If there is more than the 'critical density', gravity will put a brake on its expansion, and it may soon begin to contract again to end in a Big Crunch. If there is much less, it may go on expanding forever.

What is Inflation?

Inflation was when dramatic expansion and cooling took place just a tiny fraction of a second after the Big Bang.

How did the first Galaxies form?

Galaxies formed from lumps of clouds of hydrogen and helium, as concentrations within the clumps drew together. The youngest known galaxy (right) is just 500 million years old and typical of the galaxies of the early Universe.

What shape is the Universe?

Scientists do not yet know – rather like early humankind had no way of knowing the shape of our own Earth. Perhaps the Universe is flat, perhaps it is a curve or perhaps even a sphere.

'All the galaxies

are speeding apart

from each other,

rather like raisins

in a continuously

rising loaf of bread.'

How do we know that the Universe is getting bigger?

We can tell the Universe is getting bigger because distance galaxies are speeding away from us. Yet the galaxies themselves are not moving– the space in between them is stretching.

How old is the Universe?

We know that the Universe is getting bigger at a certain rate by observing how fast distance galaxies are moving apart. By working out how long it took everything to expand to where it is now, we can work out that the Universe may be about 13.7 billion years old.

'Distant Galaxies:

As their light takes

time to reach us,

distant galaxies seen

through a telescope

are seen as they were

millions of years ago.'

Matter and Particles

Matter is simply anything that has mass and takes up space. All matter is made up of tiny particles such as protons, neutrons and electrons.

Particles are the building blocks of the Universe.

What is the Universe made from?

The stars and clouds in space are made almost 100% of hydrogen and helium, the lightest and simplest atoms, or elements. All the other elements are quite rare. But some, such as carbon, oxygen, silicon, nitrogen and iron, can form important concentrations, as in the rocky planets like Earth, where iron, oxygen and magnesium are among the most common elements.

How were Atoms made?

Atoms of hydrogen and helium were made in the early days of the Universe when quarks in the matter soup joined together. All other atoms were made as atoms were fused together by the intense heat and pressure inside stars.

'A cloud of particles

called electrons

surrounds the

atom's nucleus.'

What Are Particles?

Particles are the basic units of matter that make up everyday objects. There are hundreds of kinds of particles, but all apart from the atom and molecule are too small to see, even with the most powerful microscope.

'Atom Smasher: - A particles accelerator

propels particles at

immense speeds to

investigate their nature.'

What is Anti-matter?

Anti-matter is the mirror image of ordinary matter. If matter and anti-matter meet, they destroy each other. Fortunately, there is no anti-matter on Earth.

'The nucleus, or centre,

of an atom is made of

protons and neutrons,

which are themselves

made of quarks.'

Which is the smallest known Particle?

The smallest particle inside the nucleus is the quark. It is less than 10-20 meters across, which means a line of ten billion billion of them would be less than meter long.

'Scattered Atoms:

The paths of subatomic particles

such as quarks, can be seen

after colliding atoms

at great speed.'

What are Quarks?

Quarks are tiny particles much smaller than atoms. They were among the first particles to form at the birth of the Universe.

✒️. Collection: Uttar Tamang