Wednesday, September 1, 2021

Creation Moment 9/2/2021 - Time & Psalm 90:4

For a thousand years in thy sight are but as yesterday when it is past, and as a watch in the night.
Psalm 90:4
 
 ".....Rovelli turned next to the idea that time flows in only one direction, from past to future. 

Unlike general relativity, quantum mechanics, and particle physics, thermodynamics embeds a direction of time
Its second law states that the total entropy, or disorder, in an isolated system never decreases over time. 

Yet this doesn’t mean that our conventional notion of time is on any firmer grounding, Rovelli said. Entropy, or disorder, is subjective: “Order is in the eye of the person who looks.” 

The equations for quantum gravity he’s written down suggest three things, he said, about what “clocks measure.” 
First, there’s a minimal amount of time—its units are not infinitely small. 
Second, since a clock, like every object, is quantum, it can be in a superposition of time readings. “You cannot say between this event and this event is a certain amount of time, because, as always in quantum mechanics, there could be a probability distribution of time passing.” 
Which means that, third, in quantum gravity, you can have “a local notion of a sequence of events, which is a minimal notion of time, and that’s the only thing that remains,” Rovelli said. 

Events aren’t ordered in a line “but are confused and connected” to each other without “a preferred time variable—anything can work as a variable.” 

Light traces a cone, or consecutively larger circles, in four-dimensional spacetime like ripples on a pond that grow larger as they travel. No information can cross the bounds of the light cone because that would require information to travel faster than the speed of light. “In spacetime, the past is whatever is inside our past light-cone,” Rovelli said, ... “So it’s whatever can affect us. The future is this opposite thing,” ... So in between the past and the future, there isn’t just a single line—there’s a huge amount of time.” epocket