Rewriting the Past
The past is set in stone, right? Everything we have learned tells us that you can not change the past, 88-MPH DeLoreans notwithstanding.
However, it would probably surprise you to learn that many highly respected scientists, as well as a few out on the fringe, are questioning that assumption, based on real evidence.
For example, leading stem cell scientist, Dr. Robert Lanza, posits that the past does not really exist until properly observed. His theory of Biocentrism says that the past is just as malleable as the future.
Specific experiments in Quantum Mechanics appear to prove this conjecture. In the "Delayed Choice Quantum Eraser" experiment, "scientists in France shot photons into an apparatus, and showed that what they did could retroactively change something that had already happened." (Science 315, 966, 2007)
Paul Davies, renowned physicist from the Australian Centre for Astrobiology at Macquarie University in Sydney, suggests that conscious observers (us) can effectively reach back in history to "exert influence" on early events in the universe, including even the first moments of time. As a result, the universe would be able to "fine-tune" itself to be suitable for life.
Prefer the Many Worlds Interpretation (MWI) of Quantum Mechanics over the Copenhagen one? If that theory is correct, physicist Saibal Mitra from the University of Amsterdam has shown how we can change the past by forgetting. Effectively if the collective observers memory is reset prior to some event, the state of the universe becomes "undetermined" and can follow a different path from before. Check out my previous post on that one.
Alternatively, you can disregard the complexities of quantum mechanics entirely. The results of some macro-level experiments twist our perceptions of reality even more. Studies by Helmut Schmidt, Elmar Gruber, Brenda Dunne, Robert Jahn, and others have shown, for example, that humans are actually able to influence past events (aka retropsychokinesis, or RPK), such as pre-recorded (and previously unobserved) random number sequences
Benjamin Libet, pioneering scientist in the field of human consciousness at the University of California, San Francisco is well known for his controversial experiments that seem to show reverse causality, or that the brain demonstrates awareness of actions that will occur in the near future. To put it another way, actions that occur now create electrical brain activity in the past.
And then, of course, there is time travel. Time travel into the future is a fact, just ask any astronaut, all of whom have traveled nanoseconds into the future as a side effect of high speed travel. Stephen Hawking predicts much more significant time travel into the future. In the future. But what about the past? Turns out there is nothing in the laws of physics that prevents it. Theoretical physicist Kip Thorne designed a workable time machine that could send you into the past. And traveling to the past of course provides an easy mechanism for changing it. Unfortunately this requires exotic matter and a solution to the Grandfather paradox (MWI to the rescue again here).
None of this is a huge surprise to me, since I question everything about our conventional views of reality. Consider the following scenario in a massively multiplayer online role playing game (MMORPG) or simulation. The first time someone plays the game, or participates in the simulation, there is an assumed "past" to the construct of the game. Components of that past may be found in artifacts (books, buried evidence, etc.) scattered throughout the game. Let's say that evidence reports that the Kalimdors and Northrendians were at war during year 1999. But the evidence has yet to be found by a player. A game patch could easily change the date to 2000, thereby changing the past and no one would be the wiser. But, what if someone had found the artifact, thereby setting the past in stone. That patch could still be applied, but it would only be effective if all players who had knowledge of the artifact were forced to forget. Science fiction, right? No longer, thanks to an emerging field of cognitive research. Two years ago, scientists were able to erase selected memories in mice. Insertion of false memories is not far behind. This will eventually perfected, and applied to humans.
At some point in our future (this century), we will be able to snort up a few nanobots, which will archive our memories, download a new batch of memories to the starting state of a simulation, and run the simulation. When it ends, the nanobots will restore our old memories.
Or maybe this happened at some point in our past and we are really living the simulation. There is really no way to tell.
No wonder the past seems so flexible.