Time

Question 1

Time

Answer 1

time would seem to move
what would be the present moment would seem to switch over time

Question 1

change

Answer 1

change is something that happens over time
eg. when a train changes locations - At t1 the train is at L1, at t2 the train is at L2, at t3 the train is at L3…and so on
change with respect to some properties would seem to just be having different such properties at different times

Question 2

How do they relate to our normal everyday moments of time such as 1:00, 2:00, 3:00

Answer 2

Option 1: These times are distinct things from our everyday moments of time - Just as normal events such as a train’s moving unfolds in time, so too does the unfolding of time happen in time
Call this hypertime - the unfolding of time happens in a different sort of time from the unfolding of normal
events

Question 3

Problem for hyper time

Answer 3

If hypertime is really a sort of time, then it would seem like it should be something that changes with respect to the hyperpresent
f that’s so, then it must change with respect to some time.
And if it does that then it would seem that this must be some other sort of time distinct from hypertime.
Call this hyperhypertime

• this leads to an infinite regress argument

Question 4

infinite regress

Answer 4

a certain bit of reasoning could be iterated indefinitely

Cases in which the regress isn’t bad are sometimes called virtuous regresses - bad ones are vicious regress

Question 5

Option 2 for How do they relate to our normal everyday moments of time such as 1:00, 2:00, 3:00

Answer 5

he moments t1, t2, t3 etc with respect to which the present moves are just our everyday moments of time

Problem:
According to this account when we say (i) at t1, 1:00 is present, (ii) at t2, 2:00 is present, (iii) at t3, 3:00 is present, we are really saying: (i) at 1:00, 1:00 is present, (ii) at 2:00, 2:00 is present, (iii) at 3:00, 3:00 is present
- this doesn’t explain changes in time

Question 6

the case of ‘here’

Answer 6

Sider
In Seattle Seattle is here’ is true. Similarly in Portland Portland is here’ is true, and so on.

But this doesn’t mean that being here is a property that changes over locations

Question 7

The Space-Time View

Answer 7

maybe time doesn’t move
maybe space and time are analogous
Time is another dimension in addition to the three dimension to space

On this view, events may be represented as having a temporal as well as spatial coordinates

all points of space exist in the same sense, so too, on this view, do all moments of time exist in the same sense

Question 8

temporal parts

Answer 8

Just as you have spatial parts, such as your arms, legs etc., which occupy smaller regions of space than you do, so too do you have temporal parts
that occupy smaller regions of time than you

Question 9

temporal parts solving duplication

Answer 9

when one person duplicates, it’s just the case that prior to the duplication, these two people literally overlap in sharing a large extended temporal part.

on this view, there has always been and always will be two people

Question 10

Objections to the space-time view

Answer 10

(1) Change is having different properties across time. Call this temporal heterogeneity

an object is spatially heterogeneous just in case it has different properties at different spatial regions

On the space-time view change is analogous to spatial heterogeneity, but on the space-time view time is not exactly the same as space. And the differences between the two can explain why change is different from
spatial heterogeneity

Question 11

Objections to the space-time view

Answer 11

(2) Space and time are importantly disanalogous with respect to motion

Objects move back and forth in space, but don’t move back and forth in time

Question 12

Objections to the space-time view

Answer 12

(3) How objects are spatially related to one another does not, in principle, constrain the causal relations that they can stand in. But temporal relations do: Future events cannot cause past events

Response: It is true that as a matter of fact, we don’t find future events causing past events. But this may be a mere quirk of our universe

For there to be a real disanalogy between space and time it would have to be that in a strong sense
future event could not cause past events

Question 13

time travel

Answer 13

It involves a discrepancy between time and time

she departs, travels for one hour, but
the time she reaches is not one hour from the time of departure

Question 14

external time

Answer 14

calendar, date time
the way time unfolds

Question 15

personal time

Answer 15

as an approximation we can think of this as being measured by the time traveler’s wrist watch

If the time traveller goes towards the future the wrist watch may read one hour but the difference in external time will be greater etc

We can think of personal time as coordinates that follow these events, regardless of how these line up with external time

Question 16

What unites the stages of a
space-time worm that would allow for such time travel

Answer 16

According to Lewis, what unites these stages is the same sort of mental continuity that unites anyone else

The time traveller is connected and continuous with respect to personal time, but not external time

Question 17

Can there be such backward facing
causal connections

Answer 17

according to Lewis in principle it may be that certain later events stand in
this relation to earlier events

At any rate, according to Lewis, if there can be backward causation, then there could be time travel

if you can have such backwards causation, then it follows that you can get closed causal loops

An example: A time traveler comes back and tells her younger self how to build a time machine, which she does and travels back and tells her
younger self how to build a time machine

Question 18

An argument against time travel

Answer 18

The past cannot be changed. But if time travel were possible the past could be changed. Therefore time travel is impossible

In certain cases time travel may mean
that a person is unable to do something that in other circumstances they would be able to do

Tim, who wants to go back and kill his grandfather before he is born

no matter how good he is at
shooting, Tim won’t be able to kill him, this is because, if Tim were able to kill his grandfather, then Tim wouldn’t exist to then go back in time and kill his grandfather

to say that something is compossible is to say that something can happen

eg. an ape can’t speak finnish, but i can
i may not be able to actually speak finnish but it is compossible that I am able to, as humans are able to speak finnish