ATS1835 Study Guide - Final Guide: Grandfather Paradox, Temporal Parts, Nomic
18 May 2018
School
Department
Course
Professor
TIME TRAVEL
COHERENT STORIES
Impossibilities:
- Psychological
o Logical inconsistency with our psychological ability, i.e. learning
Finnish
- Technological
o Inconsistent with our current technological reach, i.e. zika vaccine
- Physical
o Inconsistent with facts and laws of nature
▪ Note: anything physically possible must also be logically
possible
- Logical
o Law of non-contradiction
▪ No two contradictory statements are both true
o ’
▪ If two things are identical then everything true for one is true
for the other
TIME TRAVEL PROBLEMS - PG.9
Identity crisis:
If you can meet your younger self, how is it possible for you to be wholly
present in two places at once; for that would involve contradiction – I am
simultaneously in the bathroom and not in the bathroom but instead in the
kitchen.
- solution: temporal parts
The grandfather paradox:
For me to be able to go back in time to kill my grandfather is for me to be
able to prevent my own birth. I must have existed to perform the act, but not
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existed consequently.
- solution: com-possibility
Foreknowledge and prevention:
If I know what happens in the future, I cannot prevent it, because preventing it
’ , ’ have the knowledge with
which to prevent it.
- solution: com-possibility, if one acted in the past then one always did, time
travel does not need us to change the future/past, only to act in it
Closed causal loops:
I might go back in time to make a bank deposit which collects interest enough
for me to be able to build my time machine.
- solution: deny the premise as it begs the question
The logically pernicious self-inhibitor:
’ , ty
switch to prevent to firing if rocket detects the return of the probe: the rocket
will fire the probe if and only if it does not fire the probe.
- solution:
TIME TRAVEL PHYSICAL POSSIBILITIES - PG.10
The tachyonic antitelephone:
Tachyons: theoretical particles that move faster than light, backwards in time.
ö’ :
Under certain conditions, solutions to the field equations of general relativity
were possible that would allow backward time travel.
Black holes:
No practical possibility but they do ‘ ’
connecting two points in the space-time continuum.
THE STRUCTURE OF TIME - PG.11-14
Four-dimensionalism:
The past and future both exist now, as the present does.
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Presentism:
Only the present is real. The past and past objects no longer exist, the future
is not set, rather an infinitely branching tree of possibilities. This means there is
no where to go to if we were to time travel.
Personal and external time:
External time is the chronological ticking of time on a clock, whereas personal
time is what we see happen from our perspective.
- Lewis is , ‘’
‘ ’
o Temporal order (external time)
▪ 1930, 1931 then 1932, things happened chronologically
o Causal order (personal)
▪ 2016, 1930’,
and my coffee was cold
Temporal parts:
The temporal parts idea tries to explain how we, in different stages of our lives,
are just a temporal part of a whole.
WA ‘A’ TIMETRAVELLERS DO - PG.15-16
It could happen that I kill my grandfather, I could have a gun and be trained to
use it. Could it be true that I kill my grandfather? No, therefore I can and can
not kill my grandfather.
Changing the past:
The past happened ju , ’
back and change it, that is, for it to have one property before my action and a
different property after. This leads to the idea that we cannot change the future,
’ re and after, nor the present.
LEWIS 1.2
- Lewis maintains that time travel is possible
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find more resources at oneclass.com
Document Summary
Psychological: logical inconsistency with our psychological ability, i. e. learning. Inconsistent with our current technological reach, i. e. zika vaccine. Inconsistent with facts and laws of nature: note: anything physically possible must also be logically possible. Logical: law of non-contradiction, no two contradictory statements are both true, (cid:704)(cid:724)(cid:728)(cid:721)(cid:733)(cid:728)(cid:745)"(cid:738) (cid:704)(cid:720)(cid:742) (cid:734)(cid:725) (cid:701)(cid:723)(cid:724)(cid:733)(cid:739)(cid:728)(cid:739)(cid:744) If two things are identical then everything true for one is true for the other. For me to be able to go back in time to kill my grandfather is for me to be able to prevent my own birth. I must have existed to perform the act, but not existed consequently. If i know what happens in the future, i cannot prevent it, because preventing it (cid:742)(cid:734)(cid:740)(cid:731)(cid:723) (cid:732)(cid:724)(cid:720)(cid:733) (cid:728)(cid:739) (cid:742)(cid:734)(cid:740)(cid:731)(cid:723)(cid:733)"(cid:739) (cid:727)(cid:720)(cid:735)(cid:735)(cid:724)(cid:733), (cid:739)(cid:727)(cid:724)(cid:737)(cid:724)(cid:725)(cid:734)(cid:737)(cid:724) (cid:701) (cid:742)(cid:734)(cid:740)(cid:731)(cid:723)(cid:733)"(cid:739) have the knowledge with which to prevent it. Solution: com-possibility, if one acted in the past then one always did, time travel does not need us to change the future/past, only to act in it.
