Edge of the Universe: A Voyage to the Cosmic Horizon and Beyond

the first question that comes to the mind of an ordinary person is how the universe cannot be infinite at all it would seem undeniable that the receptacle of all things around us should have no boundaries if these boundaries do exist what do they even represent suppose an astronaut has reached the boundaries of the universe what would he see in front of him the long awaited Dome a solid wall or maybe a fire barrier and what's beyond it aoid another universe but can emptiness or Another Universe mean that we are at the boundary of the universe after all it does not mean that there is nothing there the void and the other Universe are also something and the universe is something that contains absolutely everything the fact is that the size of the observable universe is divided into two types the apparent size also called the Hubble radius and the real size also called the particle Horizon fundamentally both of these Horizons do not characterize the real size of the universe at all first they depend on the observer's position in space second they change with time the question of whether such a trend will change in the future is not answered by modern science but if we assume that the universe will continue to expand with acceleration then all those objects that we see now will sooner or later disappear from our field of vision the simplest method of determining distance in space is to use light however if we consider the way light travels through space we should realize that the objects we see from from Earth will not necessarily look the same in space after all it can take tens hundreds thousands or even tens of thousands of years for light from distant objects to reach our planet therefore the simplest example of time and distance differences is the light from the sun the average distance from us to the nearest star is about 150 million km the bottom line is that everything you will see in a telescope actually happened to the sun 8 minutes ago that's how long it takes for light to reach Earth the light from proximus T won't reach us until 4 years later or take a star as large as balus which has no way of bursting into a supernova even if this event were to happen now we wouldn't know about it until the middle of the 27th century of course telescopes are only one of the tools for measuring Cosmic distances and are not always able to cope with this task the farther away is the object whose distance we want to measure the more difficult it is to do so radio telescopes are great for measuring distances and making observations just inside solar system they are indeed capable of providing very accurate data but as soon as you point them outside the solar system their effectiveness decreases dramatically because of all these problems astronomers decided to resort to another method of measuring distance Parallax the method works well when it comes to stars that are relatively close to us about 100 light years away but when even this method becomes ineffective researchers use other methods the next method of determining distance is called the main sequence method it's it's based on our knowledge of how stars of certain sizes change over time first the brightness and color of the star is determined and then the values are compared to nearby stars with similar characteristics deriving an approximate distance based on this data again this method is very limited and only works in the case of stars belonging to our galaxy therefore to look farther astronomers rely on the Safi based measurement method thanks to this method many astronomers have been able to calculate the distances to Stars not only inside our galaxy but also outside of it in some cases distances of 10 million light years are involved we now have an idea of the size within the nearest galaxies but the question of the size of the universe remains open therefore we turn to an ultimatum means of measurement based on the principle of red shift or red shift the essence of red shift is similar to the principle of the Doppler effect think of a railroad crossing have you never noticed how the sound of a train horn changes depending on the distance becoming stronger as it approaches and quieter as it moves farther away leaving us stunned light works in much the same way look at the spectrogram see the black lines they indicate the limits of color absorption by chemical elements in and around the light source the more the lines are shifted to the red part of the spectrum the farther away the object is from us from spectrograms like this researchers also determine how fast an object is moving away from us so we're getting closer to our answer most of the red shifted light belongs to galaxies that that are about 13 billion years old but there's one important detail to consider it's that during all this time since the Big Bang the universe has continued to expand as if it were New Year's Eve in other words this means that the actual size of our universe is much larger than our original measurements indicate it's also worth noting that these calculations are based only on what we ourselves can see or rather what we can see in the depths of space one way or another all agree on the Infinity of the universe but interpret this Infinity in very different ways some consider the universe to be multi-dimensional where our local three-dimensional universe is only one of its layers others say that the universe is fractal which means that our local Universe could be a particle of Another Universe not to forget the various models of the Multiverse with its closed open parallel universes and wormholes and many many more different versions the number of which is limited only by human imagination but if we turn on cold realism or simply dis engage from all these hypotheses we can assume that our universe is an infinite homogeneous reservoir of all stars and galaxies moreover at any very distant point be it billions of gigap Parx away from us all conditions will be exactly the same at this point there will be exactly the same particle Horizon and Hubble sphere with the same Relic radiation at their Edge there will be the same stars and galaxies all around what's interesting is that this doesn't contradict the expansion of the universe it's not just the universe that's expanding its space itself the fact that at the moment of the Big Bang the universe emerg from a single point says only that the infinitely small practically zero sizes that were then have now turned into unimaginably large let's try to show it clearly imagine that our planet with the size of a grain of Buckwheat which its inhabitants do not care about orbits around a watermelon Sun the size of half a soccer field in this case the orbit of Neptune would be the size of a small City the area of the for cloud the moon the area of the sun's impact boundary Mars it turns out that our solar system is as big as Earth as Mars is bigger than buckwheat but that's just the beginning now let's imagine that this buckwheat Gro is our system then the Milky Way would be the size of two soccer stadiums but even that wouldn't be enough we'd have to shrink the Milky Way down to centimeter size it will resemble a coffee foam wrapped in a whirlpool in the middle of coffee black Intergalactic space in 20 cm from it will be located the same spiral Crum the Andromeda nebula around them will be a swarm of small galaxies of our local cluster the visible size of our universe will be about 9 km We've Come to an understanding of the universe's size however it is not enough for us to understand the scale itself it is important to realize the universe in Dynamics therefore let us imagine ourselves as Giants For Whom the Milky Way has a centimeter diameter as just noted we will be inside a ball with a radius of almost 10 km let's imagine that we are able to float like a sorcerer inside this ball to travel overcoming for a second tens of light years what would we see if our universe were infinite of course we would see countless galaxies of all kinds in some areas there would be an abundance of galaxies but in others there would be nothing the main feature will be that visually all of them will be motionless while we will be motionless but if we take a step the galaxies themselves will move for example if we are able to see a microscopic solar system in the centimeter wide Milky Way we will be able to observe its development by moving 600 M away from our galaxy we can see the sun protostar and protoplanetary disc at the moment of formation as we get closer to it we will see the Earth appearing life budding and humans emerging likewise we will see galaxies reshape and move as we get farther away or closer to them while our bubble will also increase in size its changing comp components will move away from us even faster as they leave the edge of the bubble until each particle of the universe wanders in its lonely bubble with no way to interact with other particles yes so far modern science has no information about what the real size of the universe is and whether it has boundaries but we do know that the observable universe has an apparent and a true boundary called the Hubble radius and the particle radius respectively these boundaries depend entirely on the observer's position in space and expand with time if the the Hubble radius expands strictly at the speed of light then the expansion of the particle Horizon is accelerated the question whether its acceleration of the particle Horizon will continue further and will not change to contraction forever absorbing what appeared so long remains open [Applause] [Music] [Applause] [Music] for [Music] [Applause] [Music] [Applause] [Music] [Applause] [Applause] [Music] [Applause] [Music] [Applause] [Music] [Applause] [Music] h [Music] [Applause] [Music] [Applause] [Music] [Applause] [Music]