time, time travel and causal loops
TRANSCRIPT
-
7/27/2019 Time, Time Travel and Causal Loops
1/23
-
7/27/2019 Time, Time Travel and Causal Loops
2/23
Time
Before we can discuss awesome things like
time travel and causal loops we need to
determine what time is first
What do you guys think?
-
7/27/2019 Time, Time Travel and Causal Loops
3/23
Presentism
Only the present moment exists, the past and
future do not.
-
7/27/2019 Time, Time Travel and Causal Loops
4/23
Clarification
Conventionally, time is divided into three distinct regions;the past, the present, and the future. the past is
generally seen as being immutably fixed (i.e. it is totallyunchangeable), and the future as undefined and nebulous(i.e. unclear, vague).
As time passes, the moment that was once the presentbecomes part of the past; and part of the future, in turn,
becomes the new present. In this way time is said to pass, with a distinct present
moment "moving" forward into the future and leaving thepast behind.
What are the implications of this viewpoint for time travel?
-
7/27/2019 Time, Time Travel and Causal Loops
5/23
Four-dimensionalism/Eternalism
Future events are "already there",
there is no objective flow of time.
The entire universe is contained
within the block
It is sometimes referred to as the
"Block Time" or "Block Universe"
theory due to its descriptionof space-time as an unchanging
four-dimensional "block"
-
7/27/2019 Time, Time Travel and Causal Loops
6/23
Clarification
Eternalism considers all points in time to be
equally valid frames of referenceor equally
"real.
Essentially all moments in time are in existence
we simply do not have access to them.
The concept of the past present and future still
exist but are states of bring and are dependent ofthe direction from which you are observing it.
-
7/27/2019 Time, Time Travel and Causal Loops
7/23
The Past Where are you standing relative to this van?
Assume you are stationary.
You are located behind it, you are able to see
it traveling away from you. This is like the past
-
7/27/2019 Time, Time Travel and Causal Loops
8/23
The Future Where are you standing relative to this van?
Assume you are stationary.
You are located in front of it, it is coming towards you.This is like the future, it is already in existence and istravelling towards you at a rate of can anyone guess
-
7/27/2019 Time, Time Travel and Causal Loops
9/23
One SecondPer
Second
-
7/27/2019 Time, Time Travel and Causal Loops
10/23
Time travel
What would a presentist say about time
travel?
What would an eternalist say about time
travel?
What does science say about time travel?
Though the science in fascinating we are focusing
on philosophy here though there is some
support for the eternalist viewpoint.
-
7/27/2019 Time, Time Travel and Causal Loops
11/23
Time travel
Let us assume an eternalist perspecitve:
If we do so time travel is possible
I cant waitor perhaps I am already back from the
future and therefore know all the secrets about
the universe
What are some of the problems we now face?
-
7/27/2019 Time, Time Travel and Causal Loops
12/23
Problems
How do I age if I go back in time?
What happens to everyone elses time if I go
back to the past or forward into the future?
What happens if I change something in the
past?
Any others.
-
7/27/2019 Time, Time Travel and Causal Loops
13/23
Lets start with what happens if I change something
-
7/27/2019 Time, Time Travel and Causal Loops
14/23
Causal loops
Before we discuss this problem in a little more
detail lets talk about one of my favorite topics
in all of philosophy
Best explained through an example
-
7/27/2019 Time, Time Travel and Causal Loops
15/23
Example
Imagine if no one wrote Motzarts symphonies:
What do you mean you askwell imagine if Mozart was my favorite composerof all time and I really wanted him to sign a copy of my book containing all hissymphonies. So I build a time machine and travel back to see him taking thisbook with me. Now I slightly miscalculate and arrive before he has writteneven one of his pieces, but I ask him to sign them anyway. Unfortunately upon
my return to the time machine I left my book in Mozart's house and as Itraveled back to today my time machine broke so I was not able to go backand collect my book. Now Mozart looked at these symphonies and thought tohimselfwow these are great, he slowly copied and released them over therest of his life.
In essence we have a case where there is no composer of the music. I believe
Mozart wrote it, however there was no creativity in the process, the musicmerely materialized out of this loop.
Who wrote them?
-
7/27/2019 Time, Time Travel and Causal Loops
16/23
The Grandfather paradox
-
7/27/2019 Time, Time Travel and Causal Loops
17/23
-
7/27/2019 Time, Time Travel and Causal Loops
18/23
How can we solve this problem
Perhaps as suggested in the clip there are
multiple parallel universe theory
Every time we go back in time we create another universe
in which another reality takes place
Perhaps there is a mysterious additional law of
physics which have not yet uncovered.
Perhaps this in itself proves that time travel isimpossible
-
7/27/2019 Time, Time Travel and Causal Loops
19/23
Back to the Grandfather paradox
Is there any resolution?
All we can do really is employ the
same solutions to our causal
loops.
-
7/27/2019 Time, Time Travel and Causal Loops
20/23
Could you encounter yourself?
Is it possible that there are 3 versions of
myself in the same room at the same time?.
We normally think of time as consisting of
temporal parts i.e. as having a Continuity
Connectedness Causation
-
7/27/2019 Time, Time Travel and Causal Loops
21/23
Personal time
External time exists on a one dimensional plane (it is linear)and continues forward at a constant uninterrupted rate ofone second per second.
Conversely but not in contradiction with the notion ofexternal time is time as experienced by the individual.
This is known as personal time, it is in essence experiential.Though the time traveller will continue to age at the rate ofone second per second, he/she moves through externaltime appearing out of sequence with its ostensible linearity,thus external time is of little consequence whenconsidering his/her physical age and not a limiting factorwhen considering personal time.
-
7/27/2019 Time, Time Travel and Causal Loops
22/23
A time traveler seen from the standpoint of an
external observer.
-
7/27/2019 Time, Time Travel and Causal Loops
23/23
Cool idea to leave you with
Many years from now, a transgalacticcivilization has discovered time travel. A deep-thinking engineer wonders what would happen
if a time machine were sent back to the
singularity from which the big bang emerged.His calculations yield an interesting result: thesingularity would be destabilized, producing an
explosion resembling the big bang Needlessto say, a time machine was quickly sent on itsway.