What is time?

It depends.
When I am on a diet it is what I have to live before the next meal.


"But the particular aspect of time that I’m interested in is the arrow of time: the fact that the past is different from the future. We remember the past but we don’t remember the future. There are irreversible processes. There are things that happen, like you turn an egg into an omelet, but you can’t turn an omelet into an egg."

I would say that it is not ALL so bad.
If the omelette is good, ready to be eaten, I wouldn´t like it went back to eggs.


"The arrow of time is based on ideas that go back to Ludwig Boltzmann, an Austrian physicist in the 1870s. He figured out this thing called entropy. Entropy is just a measure of how disorderly things are. And it tends to grow. That’s the second law of thermodynamics: Entropy goes up with time, things become more disorderly. So, if you neatly stack papers on your desk, and you walk away, you’re not surprised they turn into a mess. You’d be very surprised if a mess turned into neatly stacked papers."

Unless you had a mother like mine.

"Basically, our observable universe begins around 13.7 billion years ago in a state of exquisite order, exquisitely low entropy."

How does he know?



"So the Big Bang starts it all. But you theorize that there’s something before the Big Bang. Something that makes it happen. What’s that?

If you find an egg in your refrigerator, you’re not surprised. You don’t say, “Wow, that’s a low-entropy configuration. That’s unusual,” because you know that the egg is not alone in the universe. It came out of a chicken, which is part of a farm, which is part of the biosphere, etc., etc. But with the universe, we don’t have that appeal to make. We can’t say that the universe is part of something else. But that’s exactly what I’m saying. I’m fitting in with a line of thought in modern cosmology that says that the observable universe is not all there is. It’s part of a bigger multiverse. The Big Bang was not the beginning."


"There’s different moments in the history of the universe and time tells you which moment you’re talking about. And then there’s the arrow of time, which give us the feeling of progress, the feeling of flowing or moving through time. So that static universe in the middle has time as a coordinate but there’s no arrow of time. There’s no future versus past, everything is equal to each other."


"One of things I point out is that if we do imagine that it was possible, hypothetically, to go into the past, all the paradoxes that tend to arise are ultimately traced to the fact that you can’t define a consistent arrow of time if you can go into the past. Because what you think of as your future is in the universe’s past. So it can’t be one in the same everywhere. And that’s not incompatible with the laws of physics, but it’s very incompatible with our everyday experience, where we can make choices that affect the future, but we cannot make choices that affect the past."

May be we should not define "impossible" what we cannot do.
Time is what I call the unfolding of my life.
It is a subjective feeling, no life, no time.
Since I am born, I live, I will die, I presume that this is how things work.
Because ALL WHAT I know is what I saw or see or will see (hear, feel).
And what my brain does is just reelaborating what I saw, see will see.
My knowledge is limited to the box where I live, to the world I see, the feelings I have.
If I had different eyes reality would be different.
And time?
I do not know.