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Does Time Really Pass? Simon Prosser University of St Andrews University of Durham Institute of Advanced Study Public lecture, 20 th November 2012. Does Time Really Pass? Simon Prosser University of St Andrews University of Durham Institute of Advanced Study - PowerPoint PPT Presentation
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Does Time Really Pass?
Simon ProsserUniversity of St Andrews
University of Durham Institute of Advanced StudyPublic lecture, 20th November 2012
Does Time Really Pass?
Simon ProsserUniversity of St Andrews
University of Durham Institute of Advanced StudyPublic lecture, 20th November 2012
T
Does Time Really Pass?
Simon ProsserUniversity of St Andrews
University of Durham Institute of Advanced StudyPublic lecture, 20th November 2012
Does Time Really Pass?
Simon ProsserUniversity of St Andrews
University of Durham Institute of Advanced StudyPublic lecture, 20th November 2012
Near past
Distant past
Present
Near future
Distant future
A-series
t5
t4
t3
t2
t1
t3 is earlier than t4 and
t5 but later than t1 and
t2, etc.
This is true at all times
B-series
John McTaggart’s (1908) A-series and B-series
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Near past
Distant past
Present
Near future
Distant future
A-series
The A-theory of Time
The A-theory of Time:
Time is best represented by the A-series
Time passes. There is a metaphysical asymmetry between the present and other times. The ‘Common sense’ view.
6
t5
t4
t3
t2
t1
t3 is earlier than t4 and
t5 but later than t1 and
t2, etc.
This is true at all times
B-series
The B-theory of Time
The B-theory of Time:
Time is best represented by the B-series
Times are ordered, but there is no metaphysical asymmetry between the present and any other time; there is no objective ‘now’. Time does not pass.
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= existing events
= non-existing past or future events
= the objective present
‘Moving spotlight’ A-theory
‘Growing Block’ A-theory
Presentism (A-theory)
B-theory
The Ontology of the A and B Theories
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Four arguments against the passage of time
1. McTaggart’s paradox
1. The rate at which time passes
2. Einstein’s Theory of Relativity
1. The impossibility of experiencing the passage of time
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Four arguments against the passage of time
1. McTaggart’s paradox
1. The rate at which time passes
2. Einstein’s Theory of Relativity
1. The impossibility of experiencing the passage of time
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1. McTaggart’s paradox
o McTaggart (1908, 1921) held that the A-series leads to contradiction because if time passes then every event is past AND present AND future
o He held that attempts to remove the contradiction by saying, for example, that the event was future, is now present, and will be past, fail because a new contradiction appears at the second-order level (e.g. the event must be future-future, present-present and past-past).
o In recent years, however, this argument has increasingly been found wanting
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Four arguments against the passage of time
1. McTaggart’s paradox
1. The rate at which time passes
2. Einstein’s Theory of Relativity
1. The impossibility of experiencing the passage of time
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2. The rate at which time passes
o If time passes, how quickly does it pass?
o Standard answer: one second per second!
o But can we make sense of a rate of one second per second?
13
Four arguments against the passage of time
1. McTaggart’s paradox
1. The rate at which time passes
2. Einstein’s Theory of Relativity
1. The impossibility of experiencing the passage of time
14
3. Einstein’s Theory of Relativity
o If there is an objective present time then there should be a single, objective fact about whether the two rings are simultaneous
o But according to relativity theory, if the rings are simultaneous for an observer at rest with respect to the bells then the rings will not be simultaneous for a observer moving as shown
o Is there some privileged frame of reference that determines which events are present?
15
Four arguments against the passage of time
1. McTaggart’s paradox
1. The rate at which time passes
2. Einstein’s Theory of Relativity
1. The impossibility of experiencing the passage of time
16
Could we build a device that detects the passage of time?
A B
PASSAGE DETECTORTM
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✗ ?
Why no physical device can detect the passage of time
Near past
Distant past
Present
Near future
Distant future
A-series
t5
t4
t3
t2
t1
t3 is earlier than t4 and t5 but later than t1 and t2, etc.
This is true at all times
B-series
o Physics predicts the same series of events regardless of whether the A-theory or the B-theory is true.
o So the detector would behave in the same way regardless of which theory was true.
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Why do we believe that time passes?
… we are immediately and poignantly involved in the jerk and whoosh of process, the felt flow of one moment into the next (D. C. Williams, 1951)
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Eddington on experiencing temporal passage
… consciousness, looking out through a private door, can learn by direct insight an underlying character of the world which physical measurements do not betray. (Sir Arthur Eddington, The Nature of the Physical World (1928: 91)
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The impossibility of experiencing the passage of time
o So, the nature of experience gives us no reason to believe that time passes
o However this might seem compatible with the claim that if time passes we can experience it passing
o I shall now argue that even if time did pass, we could not experience it passing
o Then, finally, I shall argue that it follows that time does not pass
21
Experiences map uniquely to worldly features
E1
E4
E3
E2
E5
Experiences
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o Suppose there were H-theorists, who believed that headaches were perceptions of H-properties instantiated by nearby clouds. They knew nothing else about H-properties.
o Can an H-theorist accept that headaches have nothing to do with H-properties, but still claim that clouds have H-properties?
o No: they have no understanding of which properties H-properties are supposed to be.
o The obvious conclusion should be that there is no such thing as an H-property.
Time does not pass
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Summary
o Our first three arguments - from McTaggart’s paradox, the rate of time’s passage, and Einstein’s theory of relativity – threaten the claim that time passes, but perhaps they are not conclusive
o However our experiences give us no reason to believe that time passes
o Even if time did pass, none of our experiences could really be experiences of time passing
o Consequently we don’t even know what it would be for time to pass
o The only reasonable conclusion to draw is that there is no such phenomenon as the passage of time, and the B-theory is correct.
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