Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

The struggle to find the origins of time

#1
C C Offline
https://astronomy.com/magazine/news/2022...ns-of-time

EXCERPTS: Everything you think you know about time comes largely from your internal experience of it. In terms of how your brain experiences the world, only the immediate present exists, and it encompasses only about one second.

We call this the present, but technically, it is called the experience of now by psychologists, philosophers, physicists, and brain researchers. Your brain generates your sense of the past through its stored memories and your sense of the future from predictions that it makes about what will happen in the next few seconds, minutes, or hours. The flow of time is an illusion based on a succession of immediate memories, your experience of now, and a succession of events you anticipate in the coming seconds. A century of accumulated knowledge from stroke victims and neurophysiological pathologies has also revealed the many brain systems — such as our prefrontal cortex, basal ganglia, and anterior insular cortex — that must work together to provide us with a sense of time.

[...] We infer from past memories and our sense of how the physical world behaves that our past did indeed occur; it is not a random hallucination of unrelated snapshots. And objects exist that can corroborate aspects of this story: diaries, photographs, video records, documents, even archaeological relics and fossils. Many of these records can be dated with independent techniques, reinforcing a self-consistent historical story.

But why do we remember the past and not the future? The reason for this asymmetry has to do with entropy — the amount of disorder in the universe. We have memories and historical records only because entropy in the past was lower than the entropy of the present...

[...] This idea that time is an emergent phenomenon from within our space-time and not present outside of it was proposed in 1983 by physicists Don Page of the University of Alberta in Edmonton and William Wootters of Williams College in Williamstown, Massachusetts. It was a dramatic solution to the origin of time, placing its source in a phenomenon called quantum entanglement.

In quantum mechanics, two particles are entangled if they interact with each other in such a way that their quantum states can no longer be described independently: That is, if you measure the quantum state of one particle, causing its fuzzy cloud of possible states to collapse to one single state, you can immediately deduce the quantum state of its partner particle. The wave function of the partner particle also collapses instantly, even if it has since zipped off to the other side of the universe. Einstein hated this because it violates the principle of causality in relativity — another way in which quantum mechanics and relativity don’t mix.

But Page and Wootters suggested that an entangled system could give rise to the phenomenon of time — and recently, scientists have begun to test this hypothesis in the lab. In 2013, experiments led by physicist Ekaterina Moreva at the Istituto Nazionale di Ricerca Metrologica in Torino, Italy, showed that the emergence of time occurs in a system of two entangled photons. If an observer uses one photon as a reference clock — or timestamp — to observe its entangled partner, the system appears to evolve in time. But to an observer comparing the entangled photons to the rest of the universe, the system remains static. This means time only emerges for observers within the universe — there can be no “outside the universe” clock where time exists.

Related to this idea of quantum entanglement is the no-boundary proposal for the origin of the Big Bang, developed by James Hartle at the University of California, Santa Barbara, and the late Stephen Hawking, as well as independently by Alexander Vilenkin at Tufts University. In 1983, they proposed that one of the universe’s four spacelike dimensions underwent quantum mechanical tunneling into a timelike dimension at the Big Bang. This triggered what Vilenkin calls “eternal inflation.” Although the universe initially was made of pure space in many dimensions, once one dimension emerged as the direction of a past-to-future succession of states, the Big Bang occurred. This triggered the progression of the universe in the direction of increasing entropy, defining the arrow of time — a critical transition. According to Smolin, without it there could be no coherent 3+1 space-time, but simply a random collection of 4D spacelike spin foams that do not lead to our physical space-time.

The bottom line. Our experience of time may be subjective and limited to a sense of now, but on the cosmic scale, time seems to be a feature of entangled relationships between objects and not a feature from outside our universe. The arrow of time is a consequence of the increasing entropy of an expanding universe since the Big Bang. It appears this precludes us from remembering the future. But at least we have our memories, courtesy of the steady march of entropy, which allows us to recover past events and stitch them into a consistent story. Lucky for us, our universe seems to have a consistent story to tell in the first place! (MORE - missing details)
Reply


Possibly Related Threads…
Thread Author Replies Views Last Post
  Consolation philosophy & the struggle of reason in Africa C C 2 636 Oct 4, 2018 05:05 AM
Last Post: Yazata



Users browsing this thread: 1 Guest(s)