Ask Ethan # 112: Should You Be Afraid of the End of the Universe?

Original author: Ethan Siegel
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What remains when everything disappears?


The end? No, the journey does not end here. Death is just another path that we all have to go. The gray rain veil of this world rises, everything turns into a silvery mirror, and then you see it ...
- J.R.R.Tolkien

[ quote not from Tolkien’s books, but from the movie “The Lord of the Rings” - approx. trans. ]

Everything that we see, know and experience in the Universe will someday end. Not only do we all have to face our demise once, but the stars themselves will burn, the galaxies will die , and even matter may someday cease to exist. More than any other questions sent to me, I was touched by a question from Gary Thomas, who cannot sleep at night thinking about this:
I stumbled upon your blog, being in search of an answer and satisfaction. I am 47 years old and not so long ago I had a fear of the end of the world, and then the end of the universe. I understand that this will not affect me or anyone in the next millions of years, but it scares me that everything that we have done and all the beauty of the world will disappear one day.

And this is the truth about the universe, which we will have to face.

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Perhaps we don’t have to think about it, because everything that exists today, at some point in the future, will cease to exist, regardless of whether we think about it or not. Let's tell the whole cosmic story about how we came here, about our distant future and what it all means. And let's not be silent about anything.



Whether you consider this world — the Earth, this life and the lives of everything that has ever been alive — beautiful, or not, it is only clear that it exists. It is real, and it is part of the reality internally connected with each of us. And for all of us to exist today, the universe needed to evolve exactly as it did. In a sense, this development was predictable:
• The Universe, appearing at the end of inflation in the form of a hot, dense state, filled with matter and radiation, has greatly expanded and cooled down.
• Protons and neutrons were formed, then atomic nuclei, then neutral atoms.
• Places of increased density have grown, led to the appearance of dense molecular clouds, from which the first stars were formed.
• These stars burned their fuel, died, brought heavy elements back to the Universe, gave rise to the next generations of stars with complex molecules and rocky planets around them.
• And over time, mergers, interactions, and the constant formation of stars have given billions of chances to develop life in the Universe in every galaxy the size of the Milky Way.



But for our existence, a certain number of very unlikely events (albeit possible) were to occur.
• There should have been fundamental constants and laws of physics governing the universe.
• The star formation region, where the Sun was formed, had to have a correct history, so that a rocky world of sufficient mass and at a proper distance from the star should appear in it, so that it could support the vital processes known to us.
• The seeds of life had to take root, and evolution had to develop exactly as it developed, so that you could appear with your body, mind, and your self-awareness.



For you to appear, it took 13.8 billion years and countless accidents. Until your birth, you did not know anything about it, you were not happy about everything that happened so that you would appear, and would not be upset by all those eons that passed when you could not feel the Universe. When you didn’t exist, the universe just went about its business.



Existence itself is also a complex concept. Are you more than the sum of all the particles of which you are composed? Can't it really be your identity? Because you existed 10 years ago (if you read this text), but not one of the atoms that make up your body, mind and muscles today was in your body ten years ago. All the particles of which you are made are absolutely interchangeable - and yet you remain yourself.



If we had passed away at that moment, the particles that made us immediately after death would be identical to those that made us up in the last moments of life. Just as the atoms of which you consist, have already gone through many incarnations as components of other living beings (and non-living substances), and at some point will become parts of other living beings.



And yes, life on Earth will ever end. In the distant future of the solar system, the Sun will become too hot for the Earth to contain liquid water. Oceans evaporate. After that, the Sun will expand to a red giant, shed the upper layers, and shrink to a white dwarf: a star corpse. And although after this many generations of stars will be born - and this process will continue a thousand times longer than the age of today's Universe - at some point the fuel for new stars will end.

Beyond these limits, the stars will be ejected one by one from the remaining galaxies, and they will plow the endless abyss between the cosmic islands of the Universe. And with the exception of the quantum motion inherent in atoms, everything is cooled to a temperature close to absolute zero. And on even larger time scales, black holes will evaporate, and only empty cold space will remain.



This condition is known as the "thermal death" of the universe. There are other theoretical possibilities, for example, the Big Break (when dark energy increases with time), Large compression (when something leads to a repeated collapse of the Universe), cyclic model (when a series of explosions and contractions occur), or a new phase transition, due to which new materials. But all the current data indicate thermal death, or Great Freezing,

This is the story the Universe tells us about itself. And this is the best story about where we are, who we are, and what awaits us all, which we were able to make up.



Does this make you sad thoughts? This is possible. I can not control your feelings.

But it does not upset me anymore.

Because death is not an infinite abyss of darkness, it is not a frightening black nothing, or something that you need to fear in life.



The state of non-existence, for that which once did not exist, and which again ceases to exist, is a return to its natural state: nothing. We are afraid when we think that nothing is the absence of something good, but I prefer to think about nothing as about the emptiness of the cosmos, which in itself constitutes the entire Universe.



Everything that exists is in this emptiness: within the limits of space and time. As far as we know, space-time and everything inside it works in perfect accordance with all the laws of the natural Universe. Including you. What you feel about this is up to you, but I do not think that this should be feared. I think you need to face it, as well as with all the other facts of existence.

Our physical existence is limited: in time it is limited by the duration of life, just as the lives of everything else that we know are limited. It is limited in space beyond our ability to reach out, see or feel something, like for everything else that ever existed. But in the Universe as a whole, there are no limitations, although it may be finite in space or time (or in both cases), just its limitations are outside our observation possibilities.



So decide for yourself what to do about it. You can despair, but I do not see anything hopeless in our situation. Now, after billions of years of non-existence, we exist. In this brief moment in a huge project of space and time, we can choose what to do and how to influence everything with which we are in contact. It will not last forever - nothing known to us is forever - but this does not mean that we cannot make the best of the time we have.

It doesn’t matter what happens when everything that we know passes, you and I will be a part of it, and the legacy of our existence will be inscribed in the fabric of space-time, from which it cannot be erased. And all the energy that ever made up your body, your mind and your personality? It has always existed in the universe, and, as far as we know, will always exist.

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