What is time?
Once upon a time is a phrase we use to tell a story, a legendary tale about something like the big bang, the dinosaurs and their extinction and many other things in life. Everything has a story behind it . "We are born, time passes and we die. So time must exist, right? The trouble is, it's tricky to pin down what time actually is.
Why is time controversial? It feels real, always there, inexorably moving forward. Time has flow, runs like a river. Time has direction, always advances. Time has order, one thing after another. Time has duration, a quantifiable period between events for example a decade. Time has a privileged present, only now is real. Time seems to be the universal background through which all events proceed, such that order can be sequenced and durations measured.
The question is whether these features are actual realities of the physical world or artificial constructs of human mentality. It seems we haven't understood what time is we've only made up many things of what we perceive it to be. People say that they feel time pass by but by what instrument like the sense of smell done by the nose or sight by the eyes do we humans use to measure time? The last time I checked we had nothing but the watch. Which leads to yet another question "who made the watch? If it was at noon that the clocked first kicked what time did he/she turn the second, minute and hour hand to?" (I know it sounds crazy hehe) but please lend me some of your "time".
"Don't be late. Arrive on time. Let's spend time. Time flies". These are phrases that we use to express it.
Huw Price, professor of philosophy at Cambridge University, claims that the three basic properties of time come not from the physical world but from our mental states: A present moment that is special; some kind of flow or passage; and an absolute direction.
"We can portray our reality as either a three-dimensional place where stuff happens over time," said Massachusetts Institute of Technology physicist Max Tegmark, "or as a four-dimensional place where nothing happens [‘block universe’] — and if it really is the second picture, then change really is an illusion, because there's nothing that's changing; it's all just there — past, present, future.
"So life is like a movie, and space-time is like the DVD," he added; "there's nothing about the DVD itself that is changing in any way, even though there's all this drama unfolding in the movie. We have the illusion, at any given moment, that the past already happened and the future doesn't yet exist, and that things are changing. But all I'm ever aware of is my brain state right now. The only reason I feel like I have a past is that my brain contains memories.
So, time — the time we know since we learned to tell time on a clock — seems to disappear when you study physics, until you get to relativity. Which I haven't, this is just some good research.
"The essence of relativity is that there is no absolute time, no absolute space. Everything is relative. When you try to discuss time in the context of the universe, you need the simple idea that you isolate part of the universe and call it your clock, and time evolution is only about the relationship between some parts of the universe and that thing you called your clock."
This is some confusing stuff and but it gets interesting. Julian Barbour, a British physicist, describes time as "a succession of pictures, a succession of snapshots, changing continuously one into another. I'm looking at you; you're nodding your head. Without that change, we wouldn't have any notion of time."
"Isaac Newton," Barbour noted, "insisted that even if absolutely nothing at all happened, time would be passing, and that I believe is completely wrong." To Barbour, change is real, but time is not. Time is only a reflection of change. From change, our brains construct a sense of time as if it were flowing. As he puts it, all the "evidence we have for time is encoded in static configurations, which we see or experience subjectively, all of them fitting together to make time seem linear."
John Polkinghorne, a quantum physicist and Anglican priest, believes that the flow and direction of time are real and relentless. It is a "mistaken argument," he said, to use relativity to assert that time is an illusion, "because no observer has knowledge of a distant event, or the simultaneity of different events, until they are unambiguously in that observer's past. And, therefore, that argument focuses on the way observers organize their description of the past and cannot establish the reality of the awaiting future."
"We live in a world of unfolding and becoming," he said.
To many physicists, while we experience time as psychologically real, time is not fundamentally real. At the deepest foundations of nature, time is not a primitive, irreducible element or concept required to construct reality. The idea that time is not real is counterintuitive. But many ideas about how the world works that humanity had taken for granted have required a complete rethink. As Tegmark puts it, "There've been so many things in physics that we thought were fundamental that turned out to be mere illusions, that we're questioning everything — even time."
What reality is depends on what time is. Is time irreducible, fundamental, an ultimate descriptor of bedrock reality? Or is our subjective sense of flowing time, generated by our brains that evolved for other purposes, an illusion?
Many physicists and philosophers now suspect that time is not fundamental; rather, time emerges out of something more fundamental — something nontemporal, something altogether different (perhaps something discreet, quantized, not continuous, smooth).
The alternative, of course, is our common intuition: time does flow, the present is superspecial as the only real moment, and the deep nature of reality is one of becoming.
I cannot decide. I'm out of time thanks for reading and let your mind wonder and wander sometime.