Theoretically, why can't we change the past?

Question

i was just watching the Time Machine today, when I decided i would ask this question. In your opinion, why can't we change the past?

Answer 1

because the past makes us who we are today....

Answer 2

If you had a time machine, and decided to use it to kill your grandfather before he met your grandmother, you will not succeed. If it worked, you would not exist, you could not kill your grandfather, thus paradox. I can easily see you having an accident and dying on your way to your grandfather. In that case, the time trip was just another event, as opposed to the paradox.Given that nature usually takes what we call the path of least resistance, your death is far, far more likely to happen than your murder plans.

That is not the only possible paradox. You cannot change your reasons for the time trip. If you did, you would not make the trip at all, thus paradox. I am sure there are other possible paradoxes I have not mentioned.

This is more a physics question, as philosophy can only provide an educated guess. That said, I would say you can visit the past. You may also influence events so your past happens properly. You cannot change your own personal past, but you can use the machine to change your own personal future.

Answer 3

"Theoretically" anything is possible, as it's not based on practice or experience. I don't want to "vault" off into space, (as much fun as that can be).
I don't believe in "time" as an abolsute, but rather as a human concept to rationalize what is unknown. This may appear to contradict my answer, but it truly doesn't.
The "past" was made of the same "stuff" as this very moment, which will immediately become the "past." Can I then go "back" & change it, or more important, why would I, & what would be the consequences? (Excellently expressed by IWILLSurvive.)
Words are so inadequate; I "doubt" we could change the "past," as it existed as this moment exists. If this were possible, where would we begin? Our entire history would be totally wiped out. Fine. Perhaps we could make it "better?" How would we know, since every cause & effect would be a chain reaction, unpredictable, unknown.
"New evidence through the study of history" doesn't change the past, only temporarily reinterprets it to be reinterpreted yet again.
Memories are subject to selectivity; this doesn't change the past, only our changing choices as to how we wish to perceive it.
Now, as the devil's advocate, &/or a non-believer in time, are there parallel universes? Parallel SELVES who enter & exit reincarnations? Is our Newtonian world nothing but a fantasy? Was I dreaming while I slept, or am I dreaming the dream when I'm "awake?" Mystics have had 100% credible experiences that make a fallacy of time.
Bottom line for me: Whether or not we can change the past, I'd choose not to. At the very least, our perceptions give us a bit of scaffolding. Time "travel"would be fascinating, but if we could change the past, how could we ever get "back" to our selves? It's possible we wouldn't even exist.
Theoretically, anything is possible.
Thank you, Third P, for starring this question, that otherwise I wouldn't have seen.

Answer 4

Well, we can't really change the things that happened in the past but we can change how we feel about what happened.
Actually, a lot of what the past is is our feelings and memories, so if we decide to view things in a more positive light, I guess we've improved the past in some way.

Answer 5

We do change the past all the time. Through the study of history, new evidence comes up that makes us reconstruct how a battle occurred. Or we find that a famous leader was really homosexual because we find love letters to his male companion. You may claim that we are not changing the past, but if you look at it you find that before history finds this evidence the past is one thing, but after the discovery, the past is something else. As such, we continually change the past.

On the personal side, we find that our memories of events change. An old flame was attractive, but in our mind we think of them as extremely beautiful. We have changed the past in our own minds, in our own lives. The past is never a stable entity but rather a complex, changing story that we constantly construct and reconstruct.

Answer 6

Let me answer you question with this: What we have to understand is that the time is an accumulation, a growth, a duration. Duration is the continuous progress of the past which gnaws into the future and which swells as it advances. It means that the past in its entirety is prolonged into the present and abides there actual and acting. Duration means that the past endures, that nothing of it is quite lost.

Doubtless we think with only a small part of our past; but it is our entire past.. .. that we desire, will and act. And since time is an accumulation, the future can never be the same as the past, for a new accumulation arises at every step.

I hope i answered your question in any way i can. Thanks for a good question.

Answer 7

What's done is done. You can only change what you would do in that same circumstance by not repeating it again. Good or bad. You can't change yesterday because it is gone and you haven't been given tomorrow yet. All you can do is change the future of the world in the day you are given for 24 hours only.

Answer 8

because we can't travel into the past. if this has something to do with the butterfly effect however, i'll give a different answer. the tiniest change on earth can have a huge impact on the future. for example. killing a blade of grass by stepping on it can kill the caterpillar who was going to feed on it, which in turn would kill the bird that will starve without the caterpillar, which in turn would kill the fox that was going to eat the bird, which will in turn diploid a rich lady from buying the fur coat made from the fox, who will spend the money instead on a homeless person, who will buy a sandwich with it, and that sandwich will give the poor owner of the restraunt motivation to carry on with his business, which will one day become the famous fast food joint we now know as mcdonalds. and all that was caused because a blade of grass was killed. :] so basially we can't change the past because we would never know of the monstrous effect it could have on the future. i hope that answer your question!!

Answer 9

Check Sir Arthur Eddington"s important book, "Time's Arrow." Extremely important to scientifically understanding why everything goes in one direction, rather than the other.

Answer 10

Theoretically, we can change the past, but that is called revisionist history and is usually reserved for political gain.

Answer 11

Time travel has been problematic due to paradoxes. A paradox though is only when we choose to believe two things that are in conflict. I believe that time travel is possible, however, most of us lack the insight into how we conceive of time to actually understand how to move through it.

A memory or a flashback can be considered travelling through time.