In an earlier post I wrote about a closed minded scientist, Quintin Cooper. He unequivocally states that time travel is not possible. Well, I am writing this article to tell you time travel is possible you just wont like the caveats as it seems you cannot travel back in time to pick the wining mega millions but time travel is definitely possible. I read this amazing article in Nautilus, subscribe if you like sciency stuff, and it got me thinking about what is really happening when we talk about relativity. So I went back to the famous train example Einstein used to describe the general theory of relativity:
This always amazed me, one of the greatest minds in history thinking about one of the most complex topics in history used such simple models to think about questions until he understood them at their most fundamental level. That suggests anyone can think about complex topics using simple initial models and variants of the problem. Even you and me!
Given the Nautilus article I wanted to understand what happens when you travel faster than the speed of light? Do you travel backwards in time? To figure this out I imagined a model where we have two suns 1000 light years apart. Each of these suns has a parallel earth revolving around it, earth 1 and earth 2, in 2018 they both have Trump in office. On earth 1 a person watching the Trump presidency and looking to the stars watching earth 2 is seeing the birth of King Ferdinand the 1st of Spain on earth 2, an event 1000 years in the past. This is because the light particles bouncing off baby Ferdinand coming from earth 2 take 1000 years to reach to our location on earth 1. On earth 1 we will see Trump declare fake news a second time 1000 years from now when the light bouncing off the earth 2 Trump finally reaches us on earth 1.
OK, fine. But what happens when we travel faster than the speed of light between two locations. Imagine two cameras each 250 light years from sun 1 or sun 2. If we look at images from Camera A we are seeing the Stamp Act, the first direct tax levied on the American Colonies, from earth 2 and we are seeing the first elected English Parliament, also known as Montfort’s Parliament, from earth 1. Clearly we are seeing events from wildly different times. Now lets imagine our space ship takes 1 year to move from camera A to camera B moving away from earth 2 towards earth 1. At Camera A when we depart we are seeing events from 1265 for earth 1 and 1765 for earth 2 due to how long it takes for the light to travel to us. When we arrive at Camera B one year later having traveled 500 light years, meaning we are traveling 500 times the speed of light, we are seeing events from the years 1766 for earth 1 and 1266 for earth 2. For astronauts on the space ship, 1 year has passed, but for the people living on earth 1, 501 years have passed so we have moved 500 years into the future. At the same time, while we are now 1 year older, we are seeing events from 501 years in the past relative to people on earth 2, as a result we have traveled backwards in time 500 years relative to people on earth 2.
Looking at the above we traveled both forward and backwards in time simultaneously. Whoa, inception!
OK now lets imagine another experiment we are in the same space ship but before we leave our earth we are going to test the spaceship by circling the earth at an altitude of approximately 6400000 meters going 500 times the speed of light. Given these parameters, we will circle the earth approximately 100 million times in throughout the year of the test flight. Now what happened to the people on earth? Are we looking at an earth that is 500 years younger, older, or both? Looking at the picture below you will see it takes 1/2000th of a second to circumnavigate the earth at an altitude of 6400km traveling at 500 times the speed of light. It takes light 1/10th of a second to travel from the surface to the orbital altitude of 6400km. So after 2000 orbits of the earth one second has passed for the astronauts and they are seeing events on earth that are 1/10th of a second old. 10000 orbits later the astronauts have lived for 5 seconds and when they pass point A they are seeing events from earth that are 1/10th of a second old. No matter how many times we circle earth we are always seeing events that are 1/10th of a second old. If you go back and look at both the picture of Einstein’s theory of relativity of my drawing of the parallel earths you will see the relativity is based on 3 elements, distance from the source of the event and direction of travel relative to the event at a given velocity. If you are very far away from the event or traveling very quickly towards or away from the event it creates a relative time difference. In this example where we are traveling very fast but staying close and not changing distance there is no difference in relativity after 1 year in the space ship 1 year as passed on earth and so no change in relative times. We traveled at 500 times the speed of light but did not experience a relative difference in time. This seems to suggest speeds impact on time is affected by the direction of travel relative to the observer. Relative time is directly correlated with direction of travel at a velocity relative to the observer or the person on earth 1 or 2.
Mathematically you can calculate the relative time differential by multiplying the vector of velocity and time by the cosign of the angle of travel relative to the observer. If you are traveling at 500 times the speed of light at a 30 degree angle relative to the observer on a planet then you travel 433 years into the future while simultaneously traveling 250 years into the past. This leaves you 188 years in the future from where you started, 433 – 250 = 188 as a result of your year of travel. If you are traveling at a 60 degree angle then you travel 250 into the future and 433 into the past leaving you 188 years in the past at the end of your year of travel.
But seriously, what the hell is time?
It seems to me that looking at the 2 earths example all of the times exist simultaneously that is why we can see all times depending on your place relative to the earths. So that means time is dictated by the movement of light waves, or, since the same type of experiment would work using closed eyes and sound, waves in general? In this case, there are a set of waves emanating from a source, earth 1 and 2, and your distance from a source dictates your experience of time relative to a person’s experience of time on that earth. Additionally, your movement relative to that source dictates the relative time difference between yourself and a person sitting on the source. So yes you can travel back in time, just fly away from earth very fast and you will see the past. Travel 100m light years away from earth instantaneously with a really good telescope and you will see dinosaurs roaming the earth. Note how this view of time travel avoids the grandfather paradox because once you have traveled far enough away to travel back in time, you are also so far away that you cannot impact the state of things on earth. And when you travel back to earth, you will return at exactly the same age you would have been if you had never left.
Going through this thought process suggests to me that time is a facet of how our minds process neural inputs. Our minds process the current state our senses. Then our minds process our sensory state again, and again, and again as fast as the mind can process the neural state data. Think of it like a line or queue, our neurons send information to our brain and our brain processes them as quickly as it can. The sequence of events and the number of times your brain processes the inputs I hypothesize causes the sensation of time. In essence, time is the “clock speed” of our brains. It is entirely possible we could eventually discover a species that has a mental clock speed faster than humans. In fact, wrestling with my dog I often think he is capable of processing inputs faster than I can so perhaps we have already discovered species that have a higher clock speed than humans?
Based on that hypothesis, looking for the ability to travel in time will require something other than physical movement through the stars or we have to accept that our time frame of reference is rooted to our physical location and we can only travel in time moving to other locations great distances away which seems to defeat the whole point of time travel. (Although I would like to see my father again even if only from a great distance knowing I cannot talk to him…)
Maybe this make sense to you maybe not, what matters is it makes sense to me. Getting these images in my mind helped me understand the theory of relativity better than ever. At work I do the same thing, I look for the simplest model I can use to understand how things work then layer complexity on from there if complexity is even necessary. I hope this model of thinking can help you digest complex topics better.