What is the Largest Structure in the Universe?

[00:00:00]Welcome to Astronomy Explained.

[00:00:03]What is the largest thing in the universe?

[00:00:06]A planet?

[00:00:07]A star?

[00:00:09]A galaxy?

[00:00:11]Not even close. Well, let me explain.

[00:00:15]The scale of the universe is difficult to comprehend.

[00:00:18]It feels enormous to us.

[00:00:21]Yet, more than a million Earths could fit inside the Sun.

[00:00:25]>> [music] >> And the Sun itself is only one star among hundreds of billions inside the Milky Way.

[00:00:33]But, the galaxies are not isolated.

[00:00:37]Gravity >> [music] >> pulls them together, forming larger structures.

[00:00:43]>> [music] >> Galaxies gather into groups. Groups form clusters.

[00:00:49]Clusters form superclusters.

[00:00:52]And superclusters connect together in a vast network that is stretched out across the cosmos.

[00:00:59]Scientists call this a structure the cosmic web.

[00:01:05]A gigantic [music] network of matter spanning the observable universe.

[00:01:14]If we could zoom out far enough, galaxies could not appear randomly scattered.

[00:01:21]Instead, they would arrange themselves in a vast [music] three-dimensional web.

[00:01:29]Along these filament-like galaxy clusters and superclusters, >> [music] >> between them are enormous voids.

[00:01:38]They are regions >> [music] >> of empty space containing very little matter.

[00:01:44]>> [music] >> Some of the voids are hundreds of millions of light-years [music] across.

[00:01:51]The cosmic web is held together largely by dark matter.

[00:01:55]>> [music] >> Although invisible, dark matter provides the gravitational framework up and which [music] galaxies form.

[00:02:04]Without it, the universe would likely look very sparse. [music] Over time, astronomers have discovered structures so large that they challenge our understanding of cosmic evolution.

[00:02:18]Some are stretched [music] across billions of light-years.

[00:02:22]Distances so immense that light inside them would require a significant fraction [music] of the age of the universe to cross them.

[00:02:30]Trying to imagine their physical size is almost impossible.

[00:02:36]If the Milky Way were reduced to the size of coins, some cosmic structures called [music] strings spanning the state and continents.

[00:02:45]And yet, even then, these gigantic formations exist only within the observable universe.

[00:02:54]The observable universe is the region from which light at at the known [music] time could reach us since the the Big Bang.

[00:03:05]Beyond that limit, there may be far more spaces, far more galaxies, and perhaps other structures even larger than anything we have discovered. [music] The truth is that every generation of astronomers has believed that they understand the size of the universe. And every generation has been proven wrong.

[00:03:29]The universe is always larger, always more complex, and [music] always more surprising.

[00:03:36]The largest The largest structure we know today might not hold [music] that title correct because with every new telescope and every [music] new discovery, our picture of the reality continues to expand.

[00:03:50]And perhaps the most astrophysics [music] of all this.

[00:03:57]No matter how large the structure becomes, they [music] are still only part of our universe we have by this and to understand.

[00:04:06]Thank you for watching.