Universe is expanding…why this is happening?

インデックス作成: 2026-05-15

[00:00:02]Universe is not just vast, it's expanding.

[00:00:07]Every galaxy we see is moving away from every other galaxy.

[00:00:13]Future astronomers may never know that the billions of other galaxy once existed.

[00:00:20]What is causing this expansion?

[00:00:24]Why gravity is not pulling everything back?

[00:00:28]Let's explore.

[00:00:34]Welcome back to the Vishuavappi, the journey of curious minds.

[00:00:41]In the last video, we tried to understand just how vast the universe is. And we touched on something incredible. This universe isn't just vast, but also is expanding. But how can we even say that it really is expanding?

[00:01:00]>> The answer lies in the light. We will get there. But before that, imagine this. An ambulance coming from a distance passing right by you.

[00:01:13]Pay attention to the sound.

[00:01:26]Did you notice something?

[00:01:28]The pitch was higher when it was coming towards you and lower as it move away.

[00:01:36]Why does that happen?

[00:01:38]Because sound travel as a wave.

[00:01:42]When the source of sound moves towards you, the wave gets squeezed together.

[00:01:47]They hit you more frequently.

[00:01:50]and you hear a higher pitch and when it moves away those waves stretch out they reach you less often and the pitch drop.

[00:02:02]This phenomenon is called the Doppler effect.

[00:02:07]Now the light is also a wave and it behaves in a very similar way. But here instead of hearing the change in pitch we see the change in color. When light waves get squeezed closer together they shift towards blue and when they stretch out they shift towards red.

[00:02:29]And this tiny shift tells us something incredible.

[00:02:33]By studying the color of light coming from distant galaxies, we can figure out if they are moving toward us or away from us. The surprising part, almost every galaxy we observe shows this red shift, which means they are all moving away from us.

[00:02:53]>> Now think about this.

[00:02:56]If everything in the universe is moving away from each other today, then in the past everything must have been much closer together.

[00:03:06]This idea led us to the big bang.

[00:03:10]A theory that suggests the universe began from an extremely hot dense state and has been expanding ever since. And with some analysis, brilliant minds on the earth could predict that the age of our universe could be 13.8 billion years.

[00:03:30]Long before modern science took shape, humans were already asking. What is the universe? Where did all this come from?

[00:03:39]In Rugit, one hymn describes a time where there was no sky, no space, not even the concept of existence.

[00:03:50]It doesn't rush to answers. It leans into deeper curiosity about what was there before everything.

[00:03:59]Another idea speaks about the cosmic seed. Hand garba, a single source from which everything emerge.

[00:04:10]And if you see today, modern science describe a universe that begins from an incredibly dense state, the big bang.

[00:04:20]Different words, different interpretations.

[00:04:23]But maybe they are pointing towards the same mystery or maybe not. I will let you decide.

[00:04:31]>> Coming back, the universe has evolved and galaxies are moving apart. At this point, you might wonder, are these galaxies simply flying through the space or something else is going on. Let's take a look at a real example.

[00:04:50]Meet GNZ11.

[00:04:53]This is one of the most distant galaxies we have ever observed. Its light has been traveling towards us for about 13.4 billion years.

[00:05:07]So logically, you would expect it to be at most 13.4 billion light years away.

[00:05:14]But here's where things get strange.

[00:05:17]When scientists analyzed its red shift, they estimated that today it's actually much farther away than that. So now the question becomes if nothing can travel faster than light how can something end up farther than the distance light could ever travel. This tells us that the galaxies are not just moving through the space but the space itself is expanding.

[00:05:48]>> To understand this, imagine you are baking a cake. Focus on the chocolate chips inside it. As the cake rises, the chip move further apart. Not because they are moving on their own, but because the dough itself is expanding.

[00:06:06]Galaxy are like those chocolate chips and the universe is the cake.

[00:06:12]So far, this all makes sense. The universe started expanding and as it grew the gravity should have begun pulling everything back together slowly slowing down the expansion. Right? No, that's not what we observe. In fact, we discovered something astonishing.

[00:06:33]The expansion of the universe is not slowing down. It is speeding up.

[00:06:41]>> But how do we know that? Back in the 1920s, astronomer Edwin Herbal made a groundbreaking discovery. He found that almost every galaxy is moving away from us. And even more surprising.

[00:06:56]The farther a galaxy is, the faster it is moving away.

[00:07:02]>> Let that sink in. The universe is not just expanding, it's accelerating.

[00:07:10]But now comes the biggest question of all. What is driving this expansion?

[00:07:16]If galaxies are like chocolate chips, then what is the do?

[00:07:22]>> What is causing this expansion to speed up and why the gravity is not pulling everything back?

[00:07:29]>> The answer might lie in something we call the dark energy.

[00:07:35]the mysterious form of energy that makes up nearly 68% of the universe.

[00:07:42]We don't know what it is. We don't know how it works.

[00:07:46]We only know that it exists and it is dominating the fate of the cosmos.

[00:07:55]Alongside it approximately 27% is dark matter and about 5% is the matter that we actually understand.

[00:08:06]That means about 95% of the universe is still a mystery.

[00:08:13]In the future we might not able to see many galaxies not because they died but because they are moving away so fast that their light will never reach us again.

[00:08:28]Over the billions of years more and more galaxy will fade from our view and eventually the future astronomers may only see a single galaxy in the sky.

[00:08:42]They may never know that billions of others once existed.

[00:08:48]>> And if all of this wasn't strange enough, some theories suggest that our universe could be just one bubble in the vast multiverse.

[00:08:58]Others propose that our entire universe might exist inside a black hole.

[00:09:05]And then there's an even more unsettling idea. What if all of this it's some kind of a simulation?

[00:09:14]Strange? Yes. Impossible?

[00:09:17]Not really. But these are the mysteries for another journey.

[00:09:22]>> So, here we are in a universe that isn't still, but constantly stretching, changing, and evolving. So, what do you think? Will the universe keep expanding forever?

[00:09:36]or is there something waiting ahead?

[00:09:40]Something we haven't discovered yet.

[00:09:43]Feel free to share your thoughts in the comments.

[00:09:46]Thanks for watching Vishwyappi. If you enjoyed this video, don't forget to subscribe and as always, stay curious.

[00:09:54]We are just getting started.