Understanding Einstein's Special Relativity will change your life forever: the future already exists!
Our everyday knowledge of time is that only the present 'now' exists. Everything that exists 'now' is contained in our present world (three-dimensional space). Events of the past and the future do not exist at all. The past is gone, the future not existing yet. Only the present exists. This is called presentism.
Eeinstein's Special Relativity leads to eternalism: All events in time, past, present and future co-exist. They all do not exist in our present three-dimensional space world, but in the four-dimensional spacetime 'world', also called Block Universe. The (unknown to us) future is already "out there", we just haven't reached that future yet. << Events do not happen; they are just there, and we come across them. >> (Sir Arthur Stanley Eddington, 'Space, Time, and Gravitation: An Outline of the General Relativity Theory.')
The 4D spacetime existence (Block Universe) is the essence of Einstein's Special Relativity. (Later Einstein introduced General Relativity which re-inforced this 4D spacetime reality.) The Block Universe (the Big Bang, the stars, the planets, earth and the human beings, the past, present and future) came into existence at once, the events did not develop one after the other. Only our consciousness, moving through Block Universe considers a Big Bang followed by stars and galaxies, planets, and finally life on earth. You could say that your consciousness is moving through the 'material' universe while your bodies (your past, present and future body events) actually just stay in place in Block Universe! Only your consciousness (I even dare to say: your illusion present consciousness) is moving in a frozen block of time. Like watching different frames of a movie, or reading the pages of a book. The beginning, present and the end are all already there.
For Newton (and Lorentz much later) our 3D space world is the same for everybody. Einstein showed us that two travelers moving in a different direction do not share one and the same 3D space world. Each traveler has his 'proper' 3D space world, but both travelers' 3D Space worlds share one and the same four-dimensional (4D) reality! In Einstein's Special Relativity the 4D Block Universe is invariant, not the 3D space worlds. On this site you will find out how it works.
In one sentence Einstein himself summerizes what physics became after the publication of his Special Relativity paper in 1905: << From a "happening" in three-dimensional space, physics becomes, as it were, an "existence" in the four-dimensional "world". >> (Albert Einstein. "Relativity: The Special and the General Theory." 1916. Appendix II Minkowski's Four-Dimensional Space ("World") (supplementary to section 17 - last section of part 1 - Minkowski's Four-Dimensional Space).
<< Since there exists in this four dimensional structure [space-time] no longer any sections which represent "now" objectively, the concepts of happening and becoming are indeed not completely suspended, but yet complicated. It appears therefore more natural to think of physical reality as a four dimensional existence, instead of, as hitherto, the evolution of a three dimensional existence. >> (Albert Einstein, "Relativity", 1952).
When Einstein's lifelong friend Besso died Einstein wrote a letter to Besso's family, saying that although Besso had preceded him in death it was of no consequence because: <<...for us convinced physicists the distinction between past, present, and future is only an illusion, although a persistent one." >> ( Letter to Michele Besso family, March 21, 1955. Einstein Archives 7-245).
No doubt the 4D spacetime existence (Block Universe) perspective will turn some reader's view of the world upside down. It is as shocking as discovering that the earth is not flat or that the sun is not moving around the earth.
Special Relativity's 'relativity of simultaneity' attributes a different 3D space world of simultaneous events to different observers, moving relative to each other. This leads to distortions of space and time: length contraction and time dilation. On this site you will discover how it works, but I give you already a taste of it now. Special Relativity shows how for astronauts the distances (length) to far away galaxies contract. Space contracts in the direction of movement! This has some peculiar consequences for light itself. At the speed of light the distance to be covered in the direction of traveling becomes zero! Hence for the photons it takes no time at all to travel from your flashlight to the moon! Hence for the photons the future happens at the moment they leave your flashlight now. From your point of view the light only arrives at the moon in the future. The same applies to things in the past. When at night you look at the stars the light coming from distant stars end up hitting your retinae. From the perspective of the photons, each of these photons reach you in no time, so the past has 'somehow' to be out there at the same time as your 'now'. (See also here, especially from 2:38 onwards.)
The reason I originally got stuck on Special Relativity was not because moving trains get shorter. I was captivated by Special Relativity's reciprocity of length contraction. Special Relativity not only tells us that a moving train is shorter than an immobile train, but measured from the train the railway station is contracted! How can the train be contracted relative to the railway station, and the railway station be contracted relative to the train? Seems contradictory, isn't it? Your first reaction would be that the reciprocity can only possible if the contraction in both ways is only an optical illusion. I could never accept that Einstein became famous with an optical (or mathematical!) trick. And I am correct: the length contraction has a spatio-temporal origin. The moving train is made of events of the past, present and future of that train. The 4D spacetime diagrams on this site will help you to understand how this works. I often read about moving trains that seem to get shorter ... . This is wrong, they are shorter in your 3D reality! You never say that an immobile train in front of you seems to be 60 meters long, so there's no reason pretending a moving train only 'seems' 45 meters long, as if it's an illusion. I also often read that the time for the traveler in the train runs slower. That's wrong. Very wrong. The time of train travelers never runs slower for themselves. The time of the train travellers only runs slow for me, because the train moves relative to me! And - here comes the reciprocity - because for the train passengers I move relative to them, for them my wristwatch time indications run slow!
It's mindboggling how much has been published about Special Relativity. I have studied Special Relativity before the digital age when books were the only source of information. I consulted or read more than one hundred and fifty books about or related to relativity. Why so many? Most of the books I found not interesting enough to get to the core of Special Relativity! A lot of mathematical inclined readers might be happy with a formula to get the numbers right, but there is more to physics than mathematics. Since about 2005 I stopped reading (and buying) books on Special Relativity to spend more time on the internet. But again I was -and still am- not impressed what I find there. More trains that 'appear' contracted, and more clocks that 'seem' to run slow. I became convinced there are a lot of relativity experts out there that do not understand the essence of Special Relativity: constant speed of light means physical 'relativity of simultaneity' which automatically leads to physically real Four-Dimensional (4D) Spacetime existence, (Block Universe), in which the difference between past, present and future is only a stubbornly persistent illusion.
Because in Block Universe the future already exists, there can be no free will. Many people feel very unconfortable about this. Even a lot of physicists do. With the advent of Quantum Mechanics indeterminism was introduced into nature. QM indeterminism is often put forward as evidence for the existence of free will. Karl Popper, one of the greatest philosophers of science in the twentieth century, about his encounter with Einstein: << The main topic of our conversation was indeterminism. I tried to persuade him to give up his determinism, which amounted to the view that the world was a four-dimensional Parmenidean block universe in which change was a human illusion, or very nearly so. (He agreed that this had been his view, and while discussing it I called him "Parmenides".)... >> (Karl Popper, Unended Quest: An Intellectual Autobiography.Routledge Classics. Routledge. pp.148–150). Here Popper considers Block universe = determinism, which is not necessarily the case. Block universe allows for indeterministic events popping out of nowhere (well, actually they pop-up from 4D Spacetime Block Universe!). Renowned physicist John Bell said the strange results of QM could be explained if the universe was superdetermined: << There is a way to escape the inference of superluminal speeds and spooky action at a distance. But it involves absolute determinism in the universe, the complete absence of free will. Suppose the world is super-deterministic, with not just inanimate nature running on behind-the-scenes clockwork, but with our behavior, including our belief that we are free to choose to do one experiment rather than another, absolutely predetermined, including the "decision" by the experimenter to carry out one set of measurements rather than another, the difficulty disappears. There is no need for a faster than light signal to tell particle A what measurement has been carried out on particle B, because the universe, including particle A, already "knows" what that measurement, and its outcome, will be. >> (John Bell. BBC Radio interview with Paul Davies, 1985. The quotation is an adaptation from the edited transcript of the radio interview with John Bell of 1985. See The Ghost in the Atom: A Discussion of the Mysteries of Quantum Physics, by Paul C. W. Davies and Julian R. Brown, 1986/1993, pp. 45-46). Tiny sub-atomic particles behave in the present as if they know what is going to happen to them in the future. Block Universe is a valid explanation for some peculiar expermental mysteries such as delayed choice experiments.
In Block Universe there can be no free will, unless it's an illusion! The words "I could have done differently" have no meaning in Block Universe and should in fact be abolished from language and deleted from all dictionaries. Even in a determined flow of time with no pre-existing future, free will is a very dicey concept. A will can never be free. Einstein: << I do not believe in free will. Schopenhauer's words: 'Man can do what he wants, but he cannot will what he wills,' accompany me in all situations throughout my life and reconcile me with the actions of others, even if they are rather painful to me. This awareness of the lack of free will keeps me from taking myself and my fellow men too seriously as acting and deciding individuals, and from losing my temper. >> (From "My Credo"). And: << If the moon, in the act of completing its eternal way around the Earth, were gifted with self-consciousness, it would feel thoroughly convinced that it was traveling its way of its own accord…. So would a Being, endowed with higher insight and more perfect intelligence, watching man and his doings, smile about man’s illusion that he was acting according to his own free will. >> (From a piece written as a homage to the Indian mystical poet Rabindranath Tagore). And also: << Human beings, in their thinking, feeling and acting are not free agents but are as causally bound as the stars in their motion. >> (From his address to the Spinoza Society in 1932). Even thoughts, purely a physical result of interactions between our neurons, are causally related. Free will is a contradictio in terms. And in Special Relativity the sequence of all events are not only causally related (determinism), but they all also already exist (super-determinism).
In history there are many philosophers and religious figures embracing the concept of all existing at any present moment. Augustine of Hippo wrote that God is outside of time. Time exists only within the created universe. A higher being would perceive something like a block time, while time might appear differently to the beings contained within it. Thomas Aquinas took the same view, and many theologians agree. Special Relaitvity shows that Block Universe is real. Is science finally catching up with the holy scriptures telling us about an existence beyond space and time? (For more about this, click here.)