The Observing Time Traveler HypothesisIf we knew everything about the present, we could know everything about the past. The expanded version: If it were possible to know absolutely everything about the present state of a given scenario (or universe), down to the smallest detail, and a small period into the future, we could know absolutely everything about the past of the scenario (or universe) Introduction Imagine a photo of a glass of wine that’s falling from a table top. Our experience will tell us it’s a glass falling from a table top. However, it could also be a trick, and instead be a glass being thrown upwards or perhaps even suspended in midair using invisible lines. But if we had a few more photographs that were taken shortly after the first, we would be able to say with much more certainty what had happened in the past. Add to this photograph evidence in the form of audio, video, temperature etc, and we would be able to say with 100% certainty that the glass fell off the table. Nothing interesting yet, but what if we could see the tiniest detail? For example, fresh fingerprints on the glass. Knowing the temperature of the water, the glass, and the air, and the rate of condensation as measured over a small time period, we would be able to tell whether the fingerprints were actually left exactly at the point in time as the glass was pushed off the counter top. If we could know everything about this specific scenario at a specific time and over a small time period, we would be able to tell exactly what the state of this scenario was a few moments prior, provided that this ‘scenario’ is a closed environment. What’s more amazing is that this is recursive. If we can deduce everything about the scenario a few moments ago, we could use that to figure out what the state was a few moments prior to that! Practical applications Of course, knowing everything about the present state is the tricky part. One way to get a good picture of a scenario would be to use nano-sized robots. Imagine a murder scene that happened a few hours ago. Nanobots would be able to float in, measure the temperature of the body, the blood around it and determine the exact time of death. They could measure the temperature of a bullet in the wall, the rate at which it’s cooling and the texture of the wall, thus determining how long ago the bullet was fired and the velocity of the bullet when it entered and reference-check this to determine the exact distance from which it was fired. A footprint on the carpet invisible to the naked eye will stand out clear as mud when determining the exact state of the individual fibers. Building a Time Machine With nanotechnology advanced enough to see into the past, we could also use it to recreate history using a Star-Trek like Holodeck. You could travel back in time as an observer and see things as they were 100s of years ago. Problems Chaos Theory could introduce variables. However, Chaos Theory is concerned with predicting the future, an altogether different task than “remembering” the past. We might not be able to say whether a butterfly flapping its wings today will cause it to rain in NYC tomorrow, but if we knew every detail of the universe at this exact moment, we will be able to say whether the butterfly was the cause in the past. Furthermore, storing and processing the tiniest details of the entire universe would be a monumental, if not impossible task. The main problem practically is that we might be changing the actual state by the act of observing it. Thousands of nanobots swarming around a bullet to measure its temperature will likely change its temperature. The further you “travel” back in time, the more uncertainty is introduced. There might be some far-out solutions to this, but I think I’ve done enough theorizing for today. Summary Although the time-traveler won’t be physically be going back in time, we could build a time-machine that will effectively allow the traveler to go back in time as an observer only. We are re-creating the past, today, thus bringing the past environment forward in time, rather than trying to move ourselves into a past environment. Disclaimer This idea is entirely my own, though it’s a simple idea and I therefore wouldn’t be surprized if someone had already thought of it and proven or disproven it.