We have started to explore space, but are stunned and bewildered by its expanses.
The distance to the Sun and neighboring planets was guessed at by the Greeks, but known confidently only since the late 1700s. A generation ago, we finally achieved the capability to travel out into space, and visited our nearest neighbor, the Moon, which is a few days away on our fastest human-carrying rocket. Unmanned trips to Mars take months. Jupiter and the outer planets, or inwards to our sun, would take months to years. But while those planets seem far away, compared to what lies beyond, they are just in our backyard.
We are starting to closely observe neighboring stars, and have found 547 extrasolar planets, some of which could have siblings that could resemble Earth or Mars in their size and proximity to their star. But even though these are the closest stars to us, they are very far away.
The nearest stars (besides our Sun of course) are about 4 light years away, which means it takes light beams 4 years to get there.
However, we can only travel the smallest fraction of light speed. Voyager 1 & 2 were launched in the 1970s and took 30 years to leave the solar system, and will take a few millennia to make it to interstellar distances. Of course, technology has greatly increased our capability, and it seems possible to build much faster craft. Projects Daedalus, Longshot and Icarus have proposed various methods of nuclear propulsion. However, these methods seem to get us to only about 10% of light speed, making the closest stars tens to hundreds of years distant. Magellan's voyage around the world took three years.
Project Valkyrie proposes a very ambitious system that could achieve 90% of light speed, but even then this only brings our nearest neighboring stars into practical reach.
Looking further out, we move through space with our nearby stars and thousands of others in an extended and curved cluster, one of two "arms", which extend in a spiral for vast distances. In total, these arms and connect to from a center that hundreds of millions of other stars, all of which together form the milky blur across the sky that we call the Milky Way, our galaxy, which is about 100,000 light years across. Traveling at the speeds proposed by Valkyrie, or even at light speed if that were possible, exploring and colonizing our galaxy will take time spans equivalent to the age of our species.
But even that distance is trivial. Our galaxy again seems to just be our local neighborhood, as there are an estimated 500 million other galaxies, all separated from each other by much greater distances and spanning across all of the known creation, for a total distance that we can perceive on the order of tens of billions of light years.
Within such a great expanse, we are nothing. We could never explore such a vast realm.
Or, could we? It would take a long time. We'd have to learn to be very patient.
How fast does your brain beat?
20 times per second. Yes, you may not have known it, but now you do. Your brain beats just like your heart, but at a faster rate, and with much less ado. Brain beating causes electrical pules, or waves, that can be measured by a sensitive instrument and graphed over time; a technique known as an electroencephalogram. What these measurements tell us is that the brain has a few sets of waves that run through it and coordinate the activity of the individual neurons that together make up the mental activity that we perceive as sights, sounds, emotions and mind. Some waves are a bit faster or slower, but all are within the tens of cycles per second, and the main wave, the "alpha" wave, cycles about 20 times per second. Now it just so happens that the coordinated activity of your visual and auditory sensory systems cannot detect events that happen within shorter time spans than about 1/20th of a second (which is why film and TV frame rates slightly greater than that at 24+ frames/sec seem like fluid motion). So it may be the case that this mental wave is linked to our sensory temporal resolution. Or more simply: the apparent speed of time is due to how often we observe it.
Getting back to space travel then, and to the vast time scales involved, it might be useful to see what happens if we change the frequency at which we sense the world around us. For instance, what if we thought 20 times slower? Then a whole regular minute would seem to pass in 3 seconds! This is because thinking 20 times slower means "observing" the change to the world once per second instead of twenty times per second. The effect of this is that every time we would "open our eyes" to observe things, more stuff would have happened in between, so we would think things were happening oh so much more quickly, specifically 20 times faster, or a minute taking 60s/20s per "usual" minute = 3 seconds. Or if we thought 60s per minute X 60 minutes per hour = 3600 times slower, an hour would seem to take a second. Extend this out further, and you could make any amount of time appear to take shorter (or longer if you sped up thought) than it seems to with our current senses. For instance, we might slow down enough that a trip around the galaxy would take 80 days, like it once took to get around Earth!
Let's work this out. The galaxy is 100,000 ly across, or 50,000 in radius, and so by the equation for the circumference of a circle is about 2*3.14*50,000 = 314,000ly around. If we travelled at 1/10th the speed of light, which is a reasonable limit of our theoretical propulsion technologies, then it would take 3.14M years to circumnavigate it. To have that seem to be 100 days (about 80, and makes the math easier), we would have to think so slowly that 3.14Myrs seemed like .27yrs, or about 11 million times slower than 1/20th of a second, which is 573,050 seconds or about 6.6 days per brain cycle. In other words, if we could somehow slow down our brains to the point that each beat took a week, then time would appear to pass very quickly, and a few million years would only seem like a hundred days. It is in this way, by changing ourselves, and not the laws of physics, that we can explore the galaxy, and even the universe.
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