Time travel, anyone?

In 1905 Albert Einstein (called by TIME as the “Person of the [20th] Century”) published his Special Theory of Relativity. In 1915 he again astounded the world with his General Theory of Relativity.

Last September, a team of scientists from the US, UK, Germany, and Russia “heard” gravitational waves, providing evidence, finally, that Einstein was right. Well, to be precise, more right than wrong. (Einstein never said that his thinking that the universe was static was his “biggest blunder,” but it was a blunder nonetheless.)

To understand what has happened, we have to review the last five years. In 2012 scientists discovered the Higgs boson, commonly but inaccurately called the “God Particle.” In non-scientific language, the Higgs boson explains why there is mass. It answers the classic philosophical question of “Why is there something rather than nothing?” In short, for atheists, the Higgs boson proved that there is a god, except that God is a particle (or more precisely, a field).

The Higgs boson is important in what is known as Quantum Theory, or the study of really small stuff. (Lawyers misuse the term “quantum” to mean the opposite!) The stuff is so small that no one can actually see it, except when we can feel its presence when it moves or collides with other small stuff.

When it was discovered, the Higgs boson was hailed as the “discovery of the century,” because it was the last missing piece in the puzzle of how really small stuff behaves.

Suddenly, just last month, scientists announced that they had discovered gravitational waves, another “discovery of the century.” Media (which often gets things wrong) immediately reported that we could now go on time travel. Well, that is theoretically possible but it’s going to take time to make it a reality. (Yes, I am having fun with puns!)

If the Higgs boson excites scientists working on the really small stuff, gravitational waves excite scientists working on the really big stuff. When we say “big,” we mean really big, like things that are so big that, when they collide, they move the universe. Literally.

The universe as we know it began a bit less than 14 billion years ago (measured by Earth standards). When it began, it started with a bang (and will probably end also with a bang and not a whimper). That is called the Big Bang Theory (used as the title of a comedy series whose punch lines are understood by perhaps only a tenth of its audience, just as the ten million people who bought the book entitled “A Brief History of Time” by Stephen Hawking probably never read it).

Because light cannot travel very fast (Einstein showed this in the Special Theory of Relativity), it takes time for the light from an explosion during the Big Bang to reach us here on Earth. The reason is that the universe expanded from the really small stuff that was there at the beginning of time. (Yes, time had a beginning, as Hawking wrote.)

Light from 18 billion Earth years ago has actually been reaching us for some time now, but we could not see it (more precisely, hear it) until the computers that could hear really small sounds were upgraded just last year. Finally, last September, we heard the waves coming from a collision of two black holes more or less at the beginning of time.

Imagine yourself in a beach house without a window. You cannot see the waves, but you can hear them. That is a little bit like what the scientists experienced. Their computers heard the sound of the waves but did not actually see them. But just as you would be a fool to deny that there are waves just because you could not see them from your windowless beach house, scientists are a hundred percent sure that there are waves. (You would, of course, be insane to rent a beach house without windows, which is why scientists worked for years upgrading their computer software in order to have a window to the really ancient world.)

What’s the relation between Quantum Theory and Relativity? Think of Hulk and Ant-Man, the opposite poles of a single comics universe. The two theories do not really come together, but they should and they will. Hulk and Ant-Man will indeed come together in 2018 in yet another Avengers movie (this is not a paid ad), but the two theories will not become a full “Theory of Everything” that soon.

You have to ask your physics teacher about the details, but here is a teaser: The Theory of Everything, so far, has discovered that there are at least 11 dimensions in real life (we use only four every day: height, width, depth, and time).

Now, about time travel. Since space is not just space but spacetime (yes, one word!) and since we can go back and forth in space, there seems to be no theoretical reason why we cannot go back and forth in time. But that’s just theory.

Quantum Theory, the Special Theory of Relativity, and the General Theory of Relativity were just theories, until the last five years. Did I just say “five years”? That’s according to the old view of time. I could just as well say five meters. Get it?