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Quantum theory smashed our intuitions about objects, by denying that they have definite values of physical properties that are independent of whether, or how, they are observed.
Heaven did not hand down the word ‘time’. Man invented it…. If there are problems with the concept of time, they are of our own creation … as Einstein put it ‘Time and space are modes by which we think, and not conditions in which we live.’”30
the amount of information you can cram into a region of space is proportional to the area of the surface surrounding that space.
Each pixel of spacetime has the same length, called the Planck length.
If you play a video game on your computer, such as Doom or Uncharted, you see compelling 3D worlds with 3D objects. Yet the information is entirely 2D, limited by the number of pixels on the screen.
Nothing can travel through space faster than the speed of light. But that speed limit does not apply to space itself. Where space pours into the black hole at the speed of light, it is no longer possible for light, or information, to paddle upstream fast enough to escape. This is the event horizon of the black hole, the divide between the outside, where light can escape, and the inside, where escape is not possible.
In classical physics you can specify an object’s position and momentum at the same time. You can say that the instant after a soccer player kicks a ball its position on the field is this and its momentum toward the goal is that. But not in quantum physics. If you fire an electron out of an electron gun, you can precisely measure its position or its momentum, but not both at the same time.
According to Heisenberg’s uncertainty principle, the more you know about position the less you can know about momentum, and vice versa.
rapprochement.
consternation,
Some physicists counsel avoidance of a god’s-eye view by restricting physics to the “causal diamond” of an observer—the portion of spacetime that may interact with the observer.
What is real for an agent rests entirely on what that agent experiences, and different agents have different experiences.”
Quantum states vary from observer to observer. So does spacetime itself.
At least one physicist has argued that the universe has no history apart from observers, that “histories of the universe … depend on what is being observed, contrary to the usual idea that the universe has a unique, observer independent history.”
epoch
tome,
But if spacetime is not the bedrock of reality, not the preexisting stage for the drama of life, then what is it? It is, I will suggest, a data-compressing and error-correcting code for fitness.
what physics is supposed to be about is describing things as they happen in space and time.
if there’s no spacetime, it’s not clear what physics is about.”
spacetime is doomed.
spacetime is doomed. But we don’t know what it’s replaced by.”
“What physics is supposed to be about is describing things as they happen in space and time. So, if there’s no spacetime, it’s not clear what physics is about.”
pertinent
We see objects in three dimensions not because we reconstruct objective reality, but because this is the format of a compression algorithm that evolution happened to build into us.
Perhaps distances in space encode costs of acquiring resources: an apple that costs few calories to acquire may appear just a meter away, while an apple that costs far more calories may appear much further away.
people given a drink containing glucose make shorter estimates of distance than those given a drink containing no carbohydrates
people who are more aerobically fit make shorter estimates of distance than those who are less fit.
This suggests that our perception of a distance depends not just on the energy cost, but rather on the ratio of the en...
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Slip a decimal about fitness and you may slip from life to death.
We should expect that natural selection has built redundancy into our perceptual interface, that it has shaped our desktop of spacetime and our icons of physical objects to be redundant codes for fitness payoffs that permit detection and correction of errors.
spacetime and objects are a code used by our senses to report fitness.
Vision scientists don’t claim, of course, that perception is always veridical. They admit that it can distort reality by using heuristics. But they assume that veridicality is the goal, and is normally attained.
conjectured
surfeit
purposive
ignoble
truism
Our perceptions evolved to guide adaptive exploration and action:
Spacetime is simply a species-specific
spacetime is a communications channel and physical objects are messages about fitness.
The “perceive-decide-act” (PDA) loop.
proclivity
Experiences and actions are not free. The larger your repertoire, the more calories you need, so there are selection pressures to keep these repertoires small.
olfactory
There is no consummate solution—just workable schemes that let agents survive in available niches.
We see repurposing in the unintelligent design of our eyes: light that passes through the lens of the eye must negotiate a gauntlet of blood vessels and interneurons before it chances on a photoreceptor at the back of the retina.
kludge,
Spacetime is not an objective reality independent of any observer. It is an interface shaped by natural selection to convey messages about fitness.
In sum, spacetime is not an ancient theater erected long before any stirrings of life. It is a data structure that we create now to track and capture fitness payoffs.
The human eye only sees light with wavelengths between about four hundred and seven hundred nanometers—a minuscule fraction of the entire electromagnetic spectrum. This is not just data compression, it is data deletion.
