You know the saying, "things are rarely what they seem"? The phrase is meant to encourage us to examine the way in which we view the people, and the world, around us. In fact, this phrase applies to the very laws of nature.
As we know, due to the finite speed that light travels in an almost-perfect vacuum, we are incapable of seeing things in "real time." We see the moon as it was 1.3 seconds ago, the Sun eight minutes ago, Proxima Centauri (the closest star to our solar system) as it was more than four years ago, and the Andromeda galaxy (our closest galactic neighbor) as it was more than 2.5 million years ago.
In essence, astronomy is "miraculous" in the sense that, just by looking out into the night sky, we are traveling through time. In the same way, observers in other parts of our galaxy could look at Earth's development over the course of our evolutionary timeline, and they would see the Earth as it appeared hundreds, perhaps thousands of years ago (depending on which part of the galaxy they live in and how far they are from Earth).
The same phenomenon allows us to study the universe as it appeared mere hundreds of millions of years after the big bang occurred—The most distant sources of light that were emitted from the first generation of stars and galaxies, which sprang up around 13.4 billion years ago.
We Only See a Fraction of Our Surroundings:
Something else that limits our perception of the universe is our inability to see light in all of its various forms. Light—which has properties of particles and waves—is just like the universe in that it is an expression of energy. Albeit, an extraordinarily unique expression of it. Most obvious to us is light at optical wavelengths. Then there is light at ultraviolet and infrared wavelengths. Astonishingly, our Sun only emits about 44% of its total electromagnetic radiation at optical wavelengths, the rest of its emissions come in frequencies invisible to the naked eye (but their true nature can be discerned using special tools and filters, like what we have on our telescopes).
Things of this nature are most obvious at large distances, but they are also applicable in our day-to-day lives as well, though the effects are not nearly as extreme or noticeable. Don't believe me? Let's participate in a little thought experiment:
First, close your eyes and extend both of your index fingers (though, unless you can see through your eyelids, you should probably read the rest before doing this....which may defeat the purpose, but ah well). After you've done that, take one of your fingers and touch your nose. With the other finger, touch your knee or ankle. Repeat this a few times (even better, have someone else do it), and you should be able to feel your fingers touching your nose and ankle simultaneously. Think about this for a second...the nerve signal from your ankle had to travel much farther (about twenty times over) to get to your brain than the signal from your nose did, but it feels simultaneous, doesn't it?
Basically—and this is trippy—we aren't sure if the ankle and the nose were truly touched at the same time, or if they were touched at slightly different moments, and the brain reassembled asynchronous signals, which led to the sensory information being put together at the exact same time.
There was actually an experiment done on this very subject (see the diagram below) where scientists had a group of volunteers press a button that would cause a light to flash after a small delay. After several rounds of this, they found that the volunteers were seeing the flash only milliseconds after they pushed the button, as the brain steadily "edited" the delay as it continued to get use to it—suggesting that our brains modify sensory information in different ways. Inevitably, some researchers conclude that our consciousness may exist in the past to some degree...similar to a few second delay.
Now, let's tie some of this together... if you were to stick your hand straight in front of your face, you will not see a present image of it. Instead, it will be delayed over the course of a few milliseconds due to the constraints of Einstein's theory of special relativity (given the time that it takes light to illuminate your hand, and the biological processes we must undergo before our brain can register stimulus). In addition, we must also factor in the speed of nerves traveling to the visual cortex in the back of our brain, where visual information is sorted through and the "speed of thought," which is largely different from person to person.
In conclusion, many things on a micro and macroscale are directly influenced from our perspective due to a myriad of variables placed on us by the laws of physics and our anatomy itself. There is the reflection and refraction of light scattered in our atmosphere, the observer effect witnessed with subatomic particles, light at various frequencies, and even the properties of time itself, or time dilation more specifically, whose effects can be seen on our satellites in low-Earth orbit (LEO) and the event horizons of black holes. All of this brings up an interesting philosophical question... Are we really observing reality, or can we only see into the past—glimpse the world as it was a nanosecond ago? Are we, in a sense, time travelers?
What are your thoughts?
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