Philosophy of Space and Time: Exam I

Aristotle: Why can't there only be one "now"?

-A brick wall does not exist one brick at a time, but with all of them at the same time. Time would have to consist of all nows at the same time

Galileo: what explanatory role did the aether play?

-Aether - Underlying substance from which the particles of matter and light were formed -Could wiggle and thus transmit the light from the sun through the intervening empty space to the Earth -Medium in which everything exists -It explained light, gravity, and matter -Gravity was due to the pressure differences in the aether -Working model by which many optical phenomena (Polarization, diffraction, refraction) could be quantitatively explained

Epstein: why does spaceship voyager Danny wind up younger than his twin?

-Danny used some of his speed to carry him through space and so had less speed for travel through time -his twin used all his speed for time travel

Aristotle: He says time is not composed of nows. What are two reasons he gives for this conclusion?

-If a "now" is the smallest unit of time, it would take up no time. It would be a limit continuously approaching zero -time would have to consist of all nows at the same time ex. A brick wall does not exist brick by brick, but with all bricks at the same time

Hume: contrast Hume's account of time perception with Locke's

-Locke: particular ideas are all derived from impressions of sensation and reflection, and general ideas by abstraction of reason applied to these -Hume: disagrees that the idea of time is derived from reflection, argues it is all one perception that takes time -perception extended in time

Michelson-Morley experiment

-Michelson and Morley proposed that light propagates itself through the aether -NOT the case: discovered that the speed of light is constant: in a vacuum, light travels at the same speed regardless of the velocity of the source of light or one's relative velocity -Shows that differences in the speed of light can't be used to establish absolute velocity either, and so the notion of an underlying, fixed aether (or a Newtonian absolute space) was inoperable in describing or predicting motion → the aether does not exist -Refutes Newtonian view, which at the time was considered "classical physics" -Results of the experiment: (Special Theory of Relativity) -->All motion is relative, there's no such things as absolute motion (or an aether) -->The speed of light is constant

Aristotle: How does he define a continuous quantity?

-No part of a continuous quantity can be right next to each other i.e. the number that comes right before 1 is 0.999 infinitely

Aristotle: Is time change?

-No, change can be slower or faster but time cannot -rather, we use time to describe change

St. Augustine: Does the present have duration?

-No. an instance is only present when it cannot be divided into the most minute fraction, infinitely divisible -this point in time passes so rapidly from the future to the past that is duration is without length

Aristotle: Why does Aristotle reject the notion that instants, or "nows", succeed one another?

-Nothing that is divisible and finite has only one limit -but a now is a limit, and a finite time can be grasped -therefore, time is not a quantity

Aristotle: Why can't the present have duration?

-Nows can't be simultaneous because it would either be two nows that are the same, or a now within a now -So if time is a real quantity, its parts (nows) must be successive

Leibniz: how would absolute times or spaces violate the Principle of Sufficient Reason?

-Principle of Sufficient Reason (PSR): God cannot make arbitrary decisions, all with reason

Kant: How does he argue (vs. Aristotle or Leibniz) that time is not like a concept?

-Relationists think of time as a concept, Kant argues it is more like a quantity -concepts do not have parts, they have instances (ex. Chairs are not a part of the concept of a chair. Unicorns are a part of the concept of unicorns because they have no instances) -Concepts have criteria. what would time's criteria be? -time is infinitely divisible, concepts are not

Aristotle: Why might one think he is defining time in terms of time?

-Sort of a circular argument: How can changes themselves have a temporal aspect if time is not real? -change is real, time is an abstraction, but the only way to understand change is through time

Kant: What is time?

-Time is a priori (known independently of sense-experience) and synthetic (descriptive of the world around us) -by process of elimination, the answer must be in idealism (Kant = transcendental idealist) -time is a precondition for the thought of any event -time has synthetic a priori axioms

What is time, according to Plato in Timaeus? What do the celestial bodies have to do with it?

-Time is the movement of celestial bodies -When God created the heavens, he created time as the eternal regular motion of the heavens -Notions of the past, present, and future are not applicable in the eternal

Hume: define extensionalism

-We perceive succession directly via temporally extended acts of awareness -doesn't require any backward-looking element that assumes the representation of time in the original representation of succession -experience of succession is just a succession of present acquaintances -our field of vision is made up of colored dots and their order - a special arrangement of points in space and time

Aristotle: What is his response to each of Zeno's paradoxes?

-Zeno is confusing time (the measurement) with change (the real phenomenon) -1 & 2 rest on the assumption that the time it takes to get from one place to another is actually composed of an infinite number of finite lengths of time -the 3rd assumes that time is an illusion composed of instances --> motion = motion over an interval with non-zero duration. Distance traveled per 0 seconds is not a rate of motion

Galileo: what is Galileo's Dictum?

-all smooth, linear motions are relative ex. if you are in the cabin of a moving ship and drop a coin, it will still fall straight down

St. Augustine: what was God doing before he created the universe?

-before he made heaven and Earth, God made nothing -no time could have elapsed before God made creatures / beings -God made time by making creatures

Russell: define retentionalism

-experience includes retained, fading content presented as just-past -present perception and present reverberation Ex. whistle - the past melody is reverberating, its echo is present

Paton: explain Paton's objection to Russell's retentionalism

-experience of the current location of a second hand, combined with fading sensations of past locations, would at best give you the experience of a stationary fan, brighter at one end

Parmenides: Why does Parmenides deny the possibility of change?

-if future and past events were real now, they would be present -if something is real, then it is real now

Leibniz: why is an absolute space/time incompatible with God's eternal nature?

-if space is absolute and infinite than God must be in space. Space has parts, God cannot have parts

Leibniz: what are some reasons he gives to reject absolute space or time?

-if space is absolute and infinite than God must be in space. Space has parts, God cannot have parts -Principle of Sufficient Reason (PSR): God cannot make arbitrary decisions, all with reason --> there can be no absolute space because of orientation -there's only relative location, space would not exist with nothing in it

Aristotle: Why can't time be identified with motion or some set of motions?

-if time is not a quantity, is it a process? Aristotle answers No

St. Augustine: What are our ideas of past and future of?

-impressions on our minds via sense-perception (past) -more correct to say that there is a present of past things (memory), a present of present things (direct perception), and a present of future things (expectation)

Epstein: why can't we go faster than light according to his "myth"? What does this tell us about the relationship between space and time?

-nothing can ever be done to alter the speed of anything, only its direct motion through spacetime can be altered -everything is always moving at the speed of light -even when you are at rest in a chair, you are moving through time

Post-diction

-our brains need to hold multiple presents to make sense of the world - we don't read letter by letter, but instead word by word

phi phenomenon

-stationary objects are placed side by side and illuminated rapidly one after another -gives the impression that the object is moving

Galileo: what is the relationship between Galileo's Dictum and relativity?

-the extension of Galileo's dictum to include the aetherial things (like light) as well as mechanical things (like coins) called the Principle of Relativity -relativity grows out of understanding that Galileo's dictum applies to everything

St. Augustine: Do the past and future exist?

-the past and future exist for humans, but not for God -God does not experience time pass, but rather he stands outside of it, watching all at once (eternity)

What is scientific instrumentalism?

-the purpose of physical science is to create a model that is pragmatic -helps us organize observations and predict events only as we know them

St. Augustine: does the present seem to have duration?

-there is a mental quantity that we confuse as an object fact about the world -in the end, our temporal concepts are not applicable to the world. However, we cannot put ourselves in God's shoes.

Why do Albert and Isaac (at the train station) disagree on the lightning flashes?

-they are in different inertial frames, they disagree on the temporal intervals between events -neither are wrong, they just have different frames of reference; simultaneity is relative -therefore, there is no absolute time. what time is "now" depends on one's inertial frame of reference

Aristotle: What is the relation between time and change? Can there be time without change?

-time does not exist without change

Aristotle: How is time like a number?

-time is a feature of change that makes number applicable to it -time is the quantifiable before/after aspect of change -time is not real, but it is an appropriate way of describing things that are real

St. Augustine: How do we measure lengths of time, and what does this tell us about what time is?

-time is a mental quantity. we measure time in our own minds -Freddy Mercury at Live Aid: the audience knows how to repeat the length of the call

Kant: In his Transcendental Aesthetic, how does Kant argue (vs. Locke or Newton) that the concept of time is a priori?

-time is a priori because without it, we would not understand simultaneity or succession vs. Locke: Locke says succession presupposes time, Kant says the opposite: need time before you have succession -Principles of succession and simultaneity cannot be learned through experience, but are known independently of sense-experience

Kant: What do we know about time a priori, according to Kant?

-time is a priori, known independently of sense experience -time is synthetic, it makes a substantive claim about the world -Synthetic claim: time only has one dimension, events occur on one timeline. we don't know that from experience, time is a precondition to understand those events - we have to put them on the same timeline

St. Augustine: What is the difference between time and eternity?

-time is always changing, but eternity is still

Wagon Wheel example

-we don't perceive the world continuously. we perceive 10x per second and take an 80 millisecond picture of it -we SAMPLE the world, not perceive it continuously -wagon wheel isn't actually stopping, just moving at such a speed that we take that mental picture a few times -reaction time considerably better to sound than visuals

Kant: what does he mean when he says "time is not perceived?"

-we perceive that appearances succeed one another. We are making two connections IN time, not perceiving time itself

Parmenides: summary of ideas

-we tend to talk as though the past and future both exist and do not exist -the very notion of change is incoherent -there is only What Is

Pace perceived

-when we hold up a folder and move it around the room, we see a smooth motion instead of seeing it stop at each point

Zeno: Explain Zeno's paradoxes

1. The Dichotomy -In order to reach a destination, you must cover an infinite number of finite distances 2. Achilles and the Tortoise -Achilles gives the tortoise a head start during a race -Achilles will continuously have to catch up to point A, B, C, and so on that the tortoise reaches -this will take an infinite number of steps, each of which require a finite amount of time to accomplish 3. The Arrow -An arrow flying through the air is not moving, because whether or not something is in motion should be a fact about that thing now -not a fact about its location in the past or present -therefore, motion is impossible In sum, Zeno's resolution to this is that movement, and change in general, is an illusion

Newton: what reasons does he give for the existence of absolute time?

Absolute space + time = absolute motion -space exists and is infinite

Parmenides: why does he reject the notion of the endurance of an object?

Even if there is no change, wouldn't there still be the time that passes as a thing endures? Parmenides' Response: an enduring thing would have to have temporal parts: parts that used to, do, and will exist. But then it would and would not exist; an existing thing cannot have non-existing parts

flash lag

Ex. Syncing audio and video Sounds can lag in a video more than it can lead. If the audio is behind the video we don't really notice, but if the audio is ahead of the video we do

Kant: What is the role of the concept of causation in time awareness?

How does the inference that some event A was followed by some event B? Answer: substance and cause. -organizing one's own experiences in time is a necessary condition of any coherent thought, we need to think of our experiences in relation to the things around us -the idea of temporal succession is innately present in our info-processing schemes Kant makes some good points, but if we buy too far into his idealism, we lose any objective truth.

Hume: why might one think extensionalism is an improvement on memory theory?

Memory theory: perception is confined to the present moment, and our access to past perceptual contents is via memory alone

St. Augustine: Does God experience the passage of time?

No, he stands outside of time in eternity