Repost: Is Time Travel Possible?

Posted Aug 31, 2001

NOTE: This is a repost of an article I wrote long ago I originally wrote in back around 2003 or so.

Is time travel possible? Yes and no, but mostly no. During the research I've done into time travel, I've found out that the concept is more diverse than most people think.

When talking about time travel, we must first understand there are different versions of time travel.

We can either travel forward or backward in time and can either view it or be able to participate in it. These options give us four types of time travel.

The four types of time travel:

  1. Viewing the past
  2. Participating in the past
  3. Viewing the future
  4. Participating in the future

Each of these versions has their own specific answer, so we will go over them separately. The concept of whether we return to our original time after the travel is irrelevant, as we'll discuss later on.

However, in order to understand whether time travel, in any of these forms, we must first understand the true concept of time and its relationship to space and matter.

The definition of time that I use in this article is simple:

"Time" is the passage of one moment to the next.

This definition begs, "What is a moment?".

A "moment" (for purposes of this article) is an instant defined by the position of all particles in relation to each other.

For example, one well-known moment was the precise split-second when the bullet hit John F. Kennedy's head. I will use this moment as a reference point when discussing traveling in the past.

With this in mind, let's work our way through the different types of time travel.

Viewing the past

This method is generally the one that most scientists talk about when they discuss time travel. When they talk about how time travel is possible, they usually talk about finding some way to travel faster than the speed of light. If a light beam is sent and afterward we activate time travel, we overtake the light and, in effect, see it sent off again from our new location. So when a "moment" occurs, we can head out beyond the light waves of that moment and see it again. Due to the immense distance required, this method is usually discussed in terms of traveling to solar systems far beyond our current capabilities.

In this method of time travel, we have no ability to interact with what happened. We can only observe. The most notable example of this type of time travel is stars. We see the light waves they sent off years ago, but have no way of interacting with the occurrences because they:

So with this in mind, we want to see JFK's murder. To do this we must travel faster than the light waves carrying those moments and view them.

OK, so Friday Nov. 22, 1963, 12:30:07 PM CMT is the time we are looking to witness. Around Elm Street Dallas Texas is the location.

In order to witness the event we must first calculate which direction that part of the Earth was facing so we know the best route to find the correct light waves. It does us no good to just zoom off past the speed of light. We would most likely head in the wrong direction. After all, the light waves from an event don't pass through the Earth and head out equally in all directions. Just as an astronaut on the other side of the moon could not get our attention with flares.

So we calculate the approximate location of the light waves. Now we must catch up to them.

Is faster than light speed possible? Not currently. It won't happen any time soon. Right now the most common theory as to how to do it involves bending space so you have a shorter travel distance than the light wave. However regardless of the theory and/or technique used faster than light travel still involves traveling through space faster than 186,000 miles per second. That's well out of our grasp so far. It will occur, but not yet.

But for the sake of argument let's pretend 100x light speed is currently possible. A ship takes off in the right direction, speeds out, overtakes the light rays and prepares its telescopes and recorders.

Now let's think about this for just a moment. Those light rays are going to be very far away. Well past the planet Pluto.

Let's take our best telescope (Hubble, if I'm not mistaken) and point it at Pluto. Let's pretend the telescope is 100x more powerful than it is right now. How much specific detail do you think we can see?

In a word, zero. Light dissipates as it travels just like any other wave. The details get blurrier the farther you go. This is simple physics.

We make devices to clear up and focus as best as we can, but the fact is we will never be able to make a device fast enough or clear enough to be able to zoom in on the famous assassination.

OK, so let's make things a little more reasonable. Let's pretend an attack occurred just 5 minutes ago and we can travel fast enough to see the event occur again 2 minutes from now. We can see what happened and head back to report the details missed the first time.

That is, as long as they occurred out in the open. No light waves could travel from an event, out the window and bank up toward our spacecraft for us to see and no passive "x-ray" types of technology exist. They all require us to shoot something into the area and view the results. But since what we want to see already happened, we have no chance to "x-ray" anything. No decent information would probably be available.

All this of course is still presupposed on the concept of faster than light travel, which is still much too fast for us yet. When (and if) FTL speed is reachable than this type of time travel will be possible.

However in truth it is less time travel and more space travel.

Is time travel viewing the past possible? Yes, but not yet.

Participating in the past

The classic concept of time travel in where we can travel back into time and meet Albert Einstein or our dead great grandparent.

Could we do it with faster than light speed? Nope. No matter how fast we are, what occurred, has already occurred. Seeing someone pull a trigger and moving faster than light afterward could never bring you to your exact location before the event has occurred. So if this type of time travel is to be possible it must be done with some other method.

The moment of JFK's death, while famous and full of interest, holds many details that must be discussed when considering time travel.

Remember I defined a moment by the relative position of all particles to each other. In this case, the position of the bullet compared to the position of JFK's head. However, many more things were going on at that exact moment.

Where JFK was geographically speaking, where every person and animal around them were, where objects around them were, etc.

But looking at time travel with just these details is not detailed enough. A moment in time has many other factors including:

Where the Earth was in relation to the sun, where the sun was in relation to the solar system, and where the solar system was in relation to the universe.

That moment in time is defined by the location of every atom in the universe and their precise distance from each other.

Consider traveling back in time to a nighttime situation. (Remember, it's always night time somewhere on the Earth) If our time machine only affected the Earth, then the Sun, stars, planets, etc would be in the wrong location, and a "hiccup" would be felt by all.

So traveling back in time can't be accomplished by simply recreating the exact situation, since we must also recreate the position of the very stars. our device would have to affect the entire universe. This is entirely impossible. Under no circumstances could we ever affect the entire universe to replay a past event.

Is time travel participating in the past possible? No.

Viewing the future

This concept of time travel involves being able to witness future events and travel back to the original time to what we would consider the present so you can act upon that knowledge.

While it is very possible to guess at what the future holds (as many know I'm a big proponent of predicting the future, but that's for another article) Let's look at what this type of time travel requires.

To view the future, we have to:
  1. Move forward to view the event
  2. Move back again to act on the information

It's that second part that catches most people. As we already discussed, time travel to participate in the past is not possible.

Once we witness and event, we can't go to a time before the event occurs.

So we are stuck with only the first part. If we can view a future event but can't go back, we are then obviously pulled along the stream of time and by default interact with the future, which has now become our present. That is the fourth and final part of our discussion.

Is time travel viewing the future possible? No.

Participating in the future

This is the theory that we are able to leap far ahead in time. For example, taking a one minute journey and ending up 2,000 years into the future.

This is usually conceived in the "suspended animation" concept where time passes but your body is unaffected somehow. The best example of this is simple sleep. You close your eyes and in what feels like minutes, the entire night has gone by.

The problem with sleep is that you are still affected by time, you were simply unaware of the effects. There is no method to move into the future with out the effects of time occurring on your body.

There is no way to make time move faster and not affect the traveler. The problem is the same as traveling back. You just can't affect the entire universe. Therefore no "immediate" travel method into the future method is possible.

However eventually we will be able to improve the "suspended animation" concept so that the effects of time are greatly slowed upon the target person. They will be unaware of their surroundings during this process. They won't be able to watch and wait until it's time to stop the ride. They will "go to sleep" today, and "wake up" further in the future.

But, their travel will take the regular amount of time. Travelling 1,000 years into the future will take 1,000 years, no more, no less.

As we mentioned up above, traveling back into the past isn't possible. So if you move far into the future, it's a one way trip. Once you move into the future to make it your present, you can never go back.

Is time travel participating in the future possible. Yes.

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