Briefly about what is dark matter and dark energy?
Briefly about what is dark matter and dark energy?
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00:00Dark matter and dark energy are two mysterious substances that make up most of our universe,
00:06but their nature remains largely unknown.
00:09Although we can't see them directly, scientists are confident they exist because of the way
00:13they influence stars, galaxies, and the universe as a whole.
00:18What is dark matter?
00:20Invisible but powerful, dark matter is a mysterious type of matter that doesn't emit, absorb,
00:26or reflect light.
00:28This makes it invisible to our telescopes.
00:30However, we know it exists because it affects visible objects with its gravity.
00:36Think of it like wind.
00:37You can't see the wind, but you can feel it and see how it moves leaves.
00:42How was dark matter discovered?
00:44The idea of dark matter was first proposed in the 1930s when astronomers noticed that
00:49galaxies were rotating much faster than they should be if they were made only of visible
00:53matter, like stars and planets.
00:56If only visible matter existed, the galaxies would fly apart due to the centrifugal force
01:02of their rotation.
01:03But something invisible and very massive was holding them together.
01:07That something was called dark matter.
01:10Example, gravitational lensing.
01:13One of the proofs of dark matter comes from observing a phenomenon called gravitational
01:17lensing.
01:19Light from distant galaxies bends as it passes through areas with a lot of invisible matter,
01:24dark matter.
01:25This bending of light is similar to how glasses lenses change the direction of light.
01:30Through these effects, scientists can estimate how much dark matter is in a particular region
01:34of space.
01:36How much dark matter is there?
01:38Scientists estimate that dark matter makes up about 27% of all the mass and energy in
01:43the universe.
01:44That's five times more than all the visible matter, stars, planets, and other objects,
01:50which makes up only 5% of the universe.
01:53What is dark energy?
01:55A force stretching the universe.
01:57Dark energy is even more mysterious than dark matter.
02:01It was discovered in the late 1990s when scientists found out that the universe isn't just expanding
02:06as predicted since the Big Bang, but it's expanding faster and faster.
02:11This was surprising because it was previously thought that gravity would slow down the expansion,
02:16not speed it up.
02:18Dark energy is a hypothetical force that acts like anti-gravity, making space itself
02:24expand faster.
02:25We don't know exactly what dark energy is, but essentially, it works against gravity,
02:31pushing galaxies away from each other.
02:33Example, a balloon.
02:35Imagine our universe is like a balloon with galaxies drawn on it.
02:39If you blow up the balloon, the galaxies move apart as the balloon expands.
02:44Dark energy is like the force causing the balloon to expand faster and faster.
02:49How much dark energy is there?
02:52Dark energy makes up a whopping 68% of the universe's total energy.
02:57This means that the vast majority of the cosmos is this mysterious energy that we can't see
03:02or measure directly.
03:04Why is it important?
03:05Dark matter and dark energy are crucial to understanding how our universe is structured
03:10and how it will evolve in the future.
03:12For example, the future of the universe.
03:15If dark energy continues to accelerate the universe's expansion, one day galaxies could
03:20drift so far apart that our corner of space would become completely empty.
03:25This is called the Big Rip.
03:27The shape and structure of the universe.
03:30Dark matter explains why galaxies have the structure we observe today.
03:34Without dark matter, they would have disintegrated or looked entirely different.
03:39Existing facts and evidence.
03:42Galaxies and star clusters.
03:43We can observe groups of galaxies and stars behaving as though they contain much more
03:48matter than we can see.
03:49This means there must be something invisible inside the galaxies.
03:53This is dark matter.
03:55Cosmic microwave background.
03:57This faint radiation left over from the Big Bang can be measured by scientists.
04:01Its variations confirm the existence of dark matter, which helped shape the formation of
04:06the first stars and galaxies.
04:08Dark matter and dark energy are mysterious but extremely important parts of the universe,
04:14about which we still know very little.
04:16They play a huge role in how the universe works and are among the most exciting and
04:20challenging questions in modern science.
04:23Scientists continue to work on unraveling their mysteries, and perhaps in the future
04:28we'll learn more about what makes up this vast part of the cosmos.