“Ten Things Everyone Should Know About Time”

Cosmic Variance has an interesting and brief article about the nature of time – ten realities about time that we may not realize. They’re already brief points so I won’t try to summarize them all (go read it!), but here are some parts I like:

2. The past and future are equally real. … Intuitively we think that the “now” is real, while the past is fixed and in the books, and the future hasn’t yet occurred. But physics teaches us something remarkable: every event in the past and future is implicit in the current moment… As Einstein put it, “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.”

4. You live in the past. About 80 milliseconds in the past, to be precise. Use one hand to touch your nose, and the other to touch one of your feet, at exactly the same time. You will experience them as simultaneous acts. But that’s mysterious — clearly it takes more time for the signal to travel up your nerves from your feet to your brain than from your nose. The reconciliation is simple: our conscious experience takes time to assemble, and your brain waits for all the relevant input before it experiences the “now.” Experiments have shown that the lag between things happening and us experiencing them is about 80 milliseconds.

10. A lifespan is a billion heartbeats. … Remarkably, there exist simple scaling laws relating animal metabolism to body mass. Larger animals live longer; but they also metabolize slower, as manifested in slower heart rates. These effects cancel out, so that animals from shrews to blue whales have lifespans with just about equal number of heartbeats — about one and a half billion, if you simply must be precise. In that very real sense, all animal species experience “the same amount of time.”

Obviously these are imperfect points by virtue of being extremely simplified, but they’re pretty interesting nonetheless. I find the “you live in the past point” particularly interesting. Reality is changing faster than we can perceive it; everything you think you see is wrong (in that your perception does not match your body’s current state, albeit only by 80 milliseconds). Keanu “whoa”. 

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One Response to “Ten Things Everyone Should Know About Time”

  1. Alejandro Montejano says:

    Although all of what I read was interesting, only 2 of the 10 things we should know about time really sparked my attention. First off, the idea that the past and future are equally real wasn’t easy for me to understand at first. The past and future are both obviously real things, one no more than the other, but as I read farther into the article it all made sense. I read, “…every event in the past and future is implicit in the current moment…”. In other words, what we’re doing right now, at this very moment, is found in both the past and future. Right in the middle. They’re equal to each other in thepresent. Another interesting thing I found was that we all live in the past due to an 80 millisecond lag in what we consider our “now”. Time is allowed for everything including our brain signals. The article read, “…our conscious experience takes time to assemble, and your brain waits for all the relevant input before it experiences the “now””, which makes sense after learning about the 80 millisecond “now” lag. It was fascinating to learn that what we think is our present really isn’t and that the way we’ve been perceiving time all along wasn’t exactly as simple as we thought.

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