"For us believing physicists, the distinction between past, present and future is only a stubbornly persistent illusion."
Albert Einstein said that, but Einstein has also been wrong before. Both the Standard Model of particle physics and Einstein's own general theory of relativity are time-symmetric, meaning the physics thereof is the same whether the variable called “time” increases or decreases.
This view of the universe is called the "block universe" and it doesn't actually do away with time as a dimension so much as it does the passage of time. We don't all agree with this view that the universe is actually a static block of spacetime though. What we do all agree on is that whether the passage through time is an illusion or something real, and whether time is an emergent phenomenon or a fundamental one, we either are or perceive ourselves to be naturally drifting in one direction. This is peculiar.
Time-symmetric equations do not offer an explanation for one direction being favored over another. A common attempt at an explanation for the so-called "arrow of time" is the assertion that entropy, as per the second law of thermodynamics, always increases (order gives way to disorder in a sense), but the issue with this is that the equations offer no reason entropy couldn't have increased in the other direction instead. This attempt to circumvent the problem led to the exact same problem: Time-symmetric equations sans any concept of the present.
One bizarre possibility is that the universe also extends backward in time from the point of the Big Bang in the form of a mirror region of spacetime, also potentially infinite. This eliminates the need to explain the arrow of time and entropy by introducing an additional, equal, and opposite one that preserves the symmetry that mathematics seems to predict.
An appealing aspect of this idea is that it also solves another physics problem: The apparent asymmetry between matter and antimatter in the observable universe. The mathematics seems to predict that they should have been created in equal portions at the beginning of the universe. That said, if they had been, it would seem that it all should have "annihilated" itself as matter and antimatter do, yielding a universe of pure energy with no matter and antimatter. Instead what we see is a universe that is almost completely dominated by (dark matter, energy, and dark energy aside) matter with virtually no antimatter.
We typically describe antimatter as charge-reversed matter. While regular atoms contain positively charged protons and neutral neutrons essentially orbited by negatively charged electrons, anti-atoms contain positrons in the position of orbit, which are essentially positively charged electrons (not to be confused with protons which are matter and found in the nuclei of normal atoms). That said, there's a more profound way to think of antimatter; for all mathematical intents and purposes, it's indistinguishable from ordinary matter simply traveling backward in time. This augments the credibility of the idea that there's a mirror region of spacetime in which time and entropy flowed in the other temporal direction from the Big Bang because it also explains where all the antimatter went.
As for time travel, you have it backward. It's forward travel that's easy. In fact, it can already be done on a small scale. It's backward travel that the majority of us think will never be possible. The universe seems almost as if it has inherent prevention mechanisms regarding travel to the past, almost as if to prevent potential paradoxes associated with such travel. That said, even now, it seems it may at least eventually be possible to create a time machine that only allows one to travel back to the point at which the machine is made, but as our understanding of the universe increases, who knows? I don't like to call anything an outright impossibility before we have a "theory of everything" (essentially the unification of gravity and quantum mechanics).
Is it normal I don’t believe in time?
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"For us believing physicists, the distinction between past, present and future is only a stubbornly persistent illusion."
Albert Einstein said that, but Einstein has also been wrong before. Both the Standard Model of particle physics and Einstein's own general theory of relativity are time-symmetric, meaning the physics thereof is the same whether the variable called “time” increases or decreases.
This view of the universe is called the "block universe" and it doesn't actually do away with time as a dimension so much as it does the passage of time. We don't all agree with this view that the universe is actually a static block of spacetime though. What we do all agree on is that whether the passage through time is an illusion or something real, and whether time is an emergent phenomenon or a fundamental one, we either are or perceive ourselves to be naturally drifting in one direction. This is peculiar.
Time-symmetric equations do not offer an explanation for one direction being favored over another. A common attempt at an explanation for the so-called "arrow of time" is the assertion that entropy, as per the second law of thermodynamics, always increases (order gives way to disorder in a sense), but the issue with this is that the equations offer no reason entropy couldn't have increased in the other direction instead. This attempt to circumvent the problem led to the exact same problem: Time-symmetric equations sans any concept of the present.
One bizarre possibility is that the universe also extends backward in time from the point of the Big Bang in the form of a mirror region of spacetime, also potentially infinite. This eliminates the need to explain the arrow of time and entropy by introducing an additional, equal, and opposite one that preserves the symmetry that mathematics seems to predict.
An appealing aspect of this idea is that it also solves another physics problem: The apparent asymmetry between matter and antimatter in the observable universe. The mathematics seems to predict that they should have been created in equal portions at the beginning of the universe. That said, if they had been, it would seem that it all should have "annihilated" itself as matter and antimatter do, yielding a universe of pure energy with no matter and antimatter. Instead what we see is a universe that is almost completely dominated by (dark matter, energy, and dark energy aside) matter with virtually no antimatter.
We typically describe antimatter as charge-reversed matter. While regular atoms contain positively charged protons and neutral neutrons essentially orbited by negatively charged electrons, anti-atoms contain positrons in the position of orbit, which are essentially positively charged electrons (not to be confused with protons which are matter and found in the nuclei of normal atoms). That said, there's a more profound way to think of antimatter; for all mathematical intents and purposes, it's indistinguishable from ordinary matter simply traveling backward in time. This augments the credibility of the idea that there's a mirror region of spacetime in which time and entropy flowed in the other temporal direction from the Big Bang because it also explains where all the antimatter went.
As for time travel, you have it backward. It's forward travel that's easy. In fact, it can already be done on a small scale. It's backward travel that the majority of us think will never be possible. The universe seems almost as if it has inherent prevention mechanisms regarding travel to the past, almost as if to prevent potential paradoxes associated with such travel. That said, even now, it seems it may at least eventually be possible to create a time machine that only allows one to travel back to the point at which the machine is made, but as our understanding of the universe increases, who knows? I don't like to call anything an outright impossibility before we have a "theory of everything" (essentially the unification of gravity and quantum mechanics).