Predicting the Future and Light Speed

Click For Summary

Discussion Overview

The discussion revolves around the concept of predicting future states of a system, particularly in relation to the constraints of information transmission and the speed of light. Participants explore the implications of making predictions based on current knowledge and initial conditions, and whether such predictions could be construed as information traveling faster than light.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the nature of predictions, suggesting that knowing future states might imply information from the future, which could violate the speed of light constraint.
  • Another participant counters that predictions do not involve information transmission, as they rely solely on current data and models, which may not account for unknown factors.
  • A later reply proposes a hypothetical scenario where complete knowledge of physical laws allows for accurate predictions, questioning the nature of information used in modeling past versus future states.
  • Participants discuss the idea that if future predictions can be made with complete accuracy, then the future does not hold new information, as all necessary information is already known.

Areas of Agreement / Disagreement

Participants express differing views on whether predicting the future can be seen as a violation of information transmission limits. There is no consensus on the implications of predictions regarding the nature of information and its relation to the speed of light.

Contextual Notes

Participants acknowledge the theoretical nature of their discussions, particularly regarding complete knowledge of physical laws and the implications for information transfer. The discussion remains open to various interpretations of how predictions relate to information and causality.

ejproducts
Messages
8
Reaction score
0
This is probably the stupidest question I have ever asked, but it is bugging me and I am looking for an illuminating answer - not one that simply tells me I have the wrong idea, but one that explains in what way I have the wrong idea.

I can, based upon some knowledge of initial conditions and some equations, predict a future state of some system. For example, I can predict the next eclipse. Now, this prediction is based upon information that I have at the present, and some of that information is the initial conditions (where the sun, moon and Earth are now) and some of that information is the equation (how they move). With this information, I can know information about a future state before it happens.

Here is the troubling bit. I know that information cannot exceed the speed of light, and if it did it would be virtually or practically traveling into the past. But when I have information of the future state of something, that seems like information "from" the future, or at least, virtually indistinguishable from information from the future. That would entail, of course, information traveling faster than the speed of light. Yet I am pretty sure this hasn't happened - no information has been transmitted in the traditional sense from one location to the other.

However, when I think about this example backwards, I feel like information has been transmitted. If I calculate an eclipse that happened in the past, it is by virtue of it happening in the past that I have the information with which I can calculate the previous eclipse. The fact that it happened contributed to my current observations which I use as my initial conditions, though I set time to -1 to calculate the past.

Why doesn't predicting the future violate the speed of light? What is different about the circumstance or the information in this case?
 
Science news on Phys.org
I don't understand why you'd think that predicting the future would violate the speed of light, since you seem to agree that no information is being transmitted. Your prediction of a future eclipse, for example, is only as good as your model and your current data. (There may well be additional factors currently unknown to you that will prevent your prediction from coming true.)
 
I see what you mean. But let's assume it is a simple set of states that I have complete knowledge of, and I can predict a future state with complete accuracy as I have managed to discover all the laws of physics. This then removes the impediments of unknown elements as far as I can see. Although this is a theoretical and unrealistic state of affairs, let's go with it.

When I build my model, the information for my model comes from somewhere. If I build a model to calculate a past state, the information for my model effectively comes from that past state, the information having traveled through time to the present state, where I can extrapolate it by creating my model. So there is no problem with this, because my information got to me by the "regular route" - all the information I calculate for the past state I calculate with the information from the past state having traveled to me at the speed of light or less.

But when I calculate a future state...

Wait, I think I've figured it out. In this scenario there's only one set of information, isn't there? So when I calculate the past or the future, I don't have any new information. Is that right?
 
ejproducts said:
Wait, I think I've figured it out. In this scenario there's only one set of information, isn't there? So when I calculate the past or the future, I don't have any new information. Is that right?
That's what I would say. If you can predict the future with 100% accuracy, then the future itself holds zero new information. You already have all the information.
 

Similar threads

Graduate Measuring the speed of light in a straight line
  • · Replies 19 ·
Replies
19
Views
2K
Undergrad Calculating distance between lux meter and light source
  • · Replies 2 ·
Replies
2
Views
2K
Graduate Can Tachyons Travel Faster Than the Speed of Light and Alter the Future?
  • · Replies 3 ·
Replies
3
Views
2K
Graduate Absolute Zero v. The Speed of Light
  • · Replies 40 ·
2
Replies
40
Views
16K
Graduate Speed of Light when not in a vacuum?
  • · Replies 5 ·
Replies
5
Views
6K
High School Why Do Events Freeze For Me at the Speed of Light?
  • · Replies 4 ·
Replies
4
Views
1K
Graduate Blazed Gratings and Littrow Mounting
  • · Replies 2 ·
Replies
2
Views
1K
High School An experiment to measure the Speed of Light
  • · Replies 14 ·
Replies
14
Views
2K
Graduate Speed of Light Thought Experiment
  • · Replies 4 ·
Replies
4
Views
2K
Graduate Why does the speed of light change in different media?
  • · Replies 4 ·
Replies
4
Views
4K