Time in a Block Universe

7/28/2019 Time in a Block Universe

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Time and the Block Universe

This page considers the nature of time itself. Using a purely logical argument - involving nophysics or mathematics whatsoever - we shall see that time must behave in a way which is

completely at odds with our usual mental conception of the passage of time. As Einstein himself

said, the flow of time is only a "stubbornly persistent illusion".

This page might very well shake the way you view the nature of time.

"There is nothing outside the universe"

The first principle to note is that ofgeneral covariance (sometimes called diffeomorphism

invariance). According to the principle of general covariance, a theory must give the same

results not matter how you move its coordinate system around in the universe (generalcovariance arose from the requirements of general relativity). To put it another way, general

covariance says that no set of coordinates is special: there is no absolute coordinate system.

Instead of object positions being defined absolutely, the position of every object in the universe

must be defined solely in terms of the position of other objects in the universe. This leadsdirectly to theprinciple of relativity.

It can be seen that general covariance inevitably arises from another simple maxim: there isnothing outside the universe. Hence, there are no absolute axes of reference for space or timeoutside the universe by which we can make our measurements (this principle - that there is

nothing outside the universe - is described as the "first principle of cosmology" by Lee Smolin inhis bookThree Roads to Quantum Gravity). (We will actually discover an exception to this

principle on the Living in the Matrix page).
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Two Theories of Time

There are two dominant - and incompatible - theories of time: the tensedtheory, and thetenseless theory. The tensed theory of time most resembles the popularly-held view of time. The

tensed theory requires there to be a present moment (the "now"), and a distinction between an

event in the past, present, and future (an event in the past was real, an event in the present is real,and an event in the future will be real). Notice that the "now" moves. This apparent movement of

the "now" is an essential feature of the tensed theory of time.


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However, there is a philosophical (and logical) problem to this idea of a moving "now". Put

simply, it raises the question which has puzzled philosophers: "How fast does time flow?". If the

"now" moves then it must move with respect to some time reference. So is it moving withrespect to itself? Surely not. To say "Time moves at the rate of one second per second"is

meaningless. Rather, the rate of time flow would have to be measured with respect to some

secondary, external time reference. However, in our earlier discussion on general covariance itwas stressed that there was no clock outside the universe, so there could not be any such

external time reference. It is simply logically impossible for there to be a moving "now". Time

does not "flow"!

So what is the alternative? The alternative is to consider a universe in which all of time is laid-out (just as the space dimension is laid-out), and there is no moving "now". All times are equally

real: as there is no special "now", there is no distinction between past and future. This forms the

tenseless theory of time.

Most physicists would favour the tenseless theory as the most accurate representation of time. It

is also calledblock universebecause all of spacetime can be viewed as being laid-out as anunchanging four-dimensional block:

For a clear explanation of the block universe, see this excellent Scientific American article by

Paul Davies.

But we all feel a "flow" of time in which an unknown and unfixed future becomes our present

moment before being relegated to the past. How can we reconcile this feeling with the block

universe in which all of time is laid-out, and there is no moving "now"? It emerges that thefeeling we have of the passing of time is nothing more than an illusion of human perception due

to the asymmetry of the time axis: we can remember the past, but we cannot remember the

future. This then gives the illusion of a flow of time with the unknown future becoming the fixedpast. For more details on this, see the Arrow of Time page.
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Here is a video in which Brian Cox explains the block universe:

However, Brian Cox's explanation is rather misleading when he shows himself travelling down

the road "into the future". If all times are equally real then he is already in the future, so no need

to travel into it - there is no need for a moving "now". In fact, it's not good that Brian Cox says inthe video: "According to Einstein, the past, present and future all exist", whereas in fact whatEinstein said was: "The distinction between past, present, and future is only a stubbornly

persistent illusion."Einstein certainly did not believe in the distinction between past, present,

and future.

Eternal Life

It might come as a surprise that this orthodox "block universe" view of time in fact leads us to

conclude that we possess a form of eternal life! This is a consequence of the principle that in the

block time model all periods of time are equally real. If a loved one dies, you might take somecomfort from the knowledge that this period of time in which your loved one is dead has, in fact,

no greater reality than the time when your loved one was alive. According to physics, it is just as

valid to consider your loved one as alive as it is to consider them dead!

Einstein took comfort from this knowledge when his lifelong friend Michele Besso died. Hewrote a letter consoling Besso's family: "Now he has departed from this strange world a little

ahead of me. That means nothing. People like us, who believe in physics, know that the

distinction between past, present, and future is only a stubbornly persistent illusion."

Of course, the flip-side is that you're already dead!

Causality in a Block Universe

If we are living in a block universe then the whole notion of causality - one event happening

before another event occurs - is mistaken. A definition of causality between two events - X and

Y - can be defined by: "We say that an event, X, causes another event, Y, if X is necessary for Y

to occur". It is then possible to have a causal chain of events happening at different times and atdifferent places in spacetime (indeed, this is the orthodox view of the structure of spacetime - see

The Hole Argument):
http://plato.stanford.edu/entries/spacetime-holearg/http://plato.stanford.edu/entries/spacetime-holearg/


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A game of tennis represented as a network of events in spacetime (based on a diagram from LeeSmolin's Three Roads to Quantum Gravity).

But if we are living in a block universe then all times (and hence all events) must be equally real.Hence, every event in the network of tennis events must be real. The notion of causality (an

event only occurring once a previous event has occurred) is therefore clearly false. David

Deutsch describes this situation in his book "The Fabric of Reality": "If we observe where one

piece of a fully-assembled jigsaw puzzle is, and we know the shapes of all the pieces, and thatthey are interlocked in the proper way, we can predict where all the other pieces are. But that

does not mean that the other pieces were causedto be where they are. If the piece we observed

was laid down first, then it was indeed among the causes of the other pieces being where they

are. If any other piece was laid down first, then the position of the piece we observed was aneffectof that, not a cause. But if the puzzle was created by a single stroke of a jigsaw-puzzle-

shaped cutter, and has never been disassembled, then none of the positions of the pieces arecauses or effects of each other."

In the block universe model of our universe, it does not make sense for one moment to be "laid

down" after another, for that would be the flow of time. We have just discussed how the flow of

time is just an illusion, so causality is just another illusion related to the psychological of time(humans order events in sequence in the direction of the psychological arrow of time, and so get

the impression that earlier events "cause" later events).

So instead of causality which is time-directed, we are just left with a network ofall the events inthe tennis game. There are still relationships between the events, but these are not causalrelationships. Rather, the relationships seem to reveal mutual dependencies between the events

which work in both the forward and backward time directions. These relationships hold together

and define the structure of spacetime.

The Astounding Implications of the Block Universe


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I do not believe the implications of the orthodox block universe model are widely realised - even

among physicists! I regularly read phrases in published papers (even from highly-reputable

authors) which make no sense at all from the point of view of the block universe. Theconclusions presented here relating to the block universe model follow directly from Einstein's

theory of general relativity and so should be considered to be orthodox physics.

According to the block universe model, every moment in time is equally real, so the whole of

space and time must be laid-out in one unchanging spacetime block:

The universe structure is one unchanging spacetime block. Essentially, this means that the wholespacetime "cone" shown above exists as an unchanging structure.

It is true that there is a time dimension defined within the universe. And for an observerwithin

the universe, objects appear to change with respect to this time axis. However, this apparent flow

of time is just an illusion of human perception due to the asymmetry of the time dimension. Asthere is no clock outside the universe, there is no "external" time axis, and the external view of

the entire universe structure can therefore never change with respect to that non-existent external

time axis. This lack of temporal change in the entire universe structure has the followingimplications:

1. The "Big Bang" does not represent the "start" of the universe. Remember, all

times are equally real in the block universe - there is nothing special about time at the

"Big Bang". As all times are equally real, the final state of the universe is just as real asthe initial state. So the so-called "initial" Big Bang tells us nothing more about the

existence of the universe than the "final" state does. While it is true that to an observer

within the universe the Big Bang might appear like the start of the universe this isrevealed to be an illusion of human perception caused by the psychological arrow of time

(for more details on this, see the Arrow of Time page).

The structure of the universe at the Big Bang does seem unusual because of its peculiar

spatial geometry. But that does not make it the "start" of the universe. All we can sayabout the entire universe structure at the Big Bang is a comment about that unusual

spatial geometry: "Along one of its dimensional axes (the backward time dimension), we
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find the spatial dimension decreasing in size until it reaches a point"(this is essentially

describing the "cone" structure in the diagram above).

2. The universe did not "emerge from nothing". It is meaningless to talk of the"start" of the universe, or the "emergence of the universe from nothing", or any other

term which implies change of the entire block universe structure over time. The entirespacetime block is laid out as one unchanging structure. Here's a quote from Stephen

Hawking's book "A Brief History of Time": "If the universe is really completely self-contained, having no boundary or edge, it would have neither beginning nor end: it

would simply be."

This means that any theory which attempts to explain the existence of the universe solelyin terms of events which happened at the Big Bang would appear to be plain wrong. This

includes any theory which suggests the reason for the existence of the universe is because

the universe "emerged from nothing" (so-called ex nihilo solutions). This includes the

theories of Tryon and Vilenkin (considered at the top of this page) which suggest that the

reason the universe exists is because it quantum tunnelled into existence from nothing.

Ex nihilo explanations for the existence of the universe are a red herring.

3. The universe is not expanding. Again, there is no temporal change in the entire

universe structure, so it is meaningless to talk of a universe which is expanding with time.After all, expansion means an increase in size with respect to some time reference. With

no external time reference axes, there is no absolute directional reference axis for time for

you to say "the universe is expanding" rather than "the universe is contracting" - one isobviously just the reverse of the other, and with no external time reference axis how

could you possibly prefer one statement over the other? (Also see Julian Barbour's article

The Non-Expanding Universe).

It seems to my mind (and to John Cruickshank who made this suggestion in a commentposted on the Arrow of Time page) that we are relying far to heavily on the psychological

arrow of time to determine our time directionality, and hence decide whether the universe

is expanding or contracting. We "perceive" the universe to be expanding because our

brains determine our feeling of directional time flow in the forward time direction. Butthat psychological arrow of time is always going to align itself from a low entropy

universe state to a high entropy universe state. That is no basis to say "the universe is

expanding" - that just says something about the distribution of entropy in the entireuniverse structure. It is more accurate to say the universe is neither expanding or

contracting. It just has a structure. It justis

.

The Wheeler-DeWitt Equation

A great puzzle in physics has been how to reconcile Einstein's theory of general relativity withquantum mechanics. General relativity remains our main theory for describing gravity, and is

extremely accurate for with large objects (stars and planets, etc.). Quantum mechanics, on the

other hand, is our main theory for dealing with microscopic objects, and the other three
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fundamental forces which act at the atomic scale (see theIt's a Small World page for a

description of those other three fundamental forces). General relativity describes space as being a

smooth surface, but quantum mechanics reveals a discontinuous microscopic world with constantfluctuations and activity. So, each of these theories is accurate in its own right but they describe

the nature of space and matter so differently that it has proven highly problematic to combine the

theories into a single unified theory.

As part of the effort to reconcile quantum mechanics and gravity, many physicists are seeking tofind a quantum theory of gravity. As part of this quest, we are going to introduce the

Hamiltonian. The Hamiltonian is an incredibly useful property of a system, which represents the

total energy of a system - the sum of the kinetic and potential energy. To be precise, theHamiltonian is the sum of the kinetic and potential energy of a closed system expressed in terms

of momentum, position, and time (see here).

But if we want to consider the Hamiltonian (total energy) of the universe we come up against a

problem. As we have just seen, there are no axes of reference outside the universe. Hence, it is

impossible to define a position for our "universe object" (so we cannot say it has a potentialenergy) and it is impossible to define a speed (so we cannot say it has kinetic energy). As

Misner, Thorne, and Wheeler say on page 457 of their book "Gravitation": "There is no suchthing as the energy (or angular momentum, or charge) of a closed universe, according to

general relativity, and this for a simple reason. To weigh something one needs a platform on

which to stand to do the weighing"(see here). So in this case, the Hamiltonian (the total energy)of the universe is zero:

This is called theHamiltonian constraint(it is actually true that the Hamiltonian is zero for any

system which has general covariance - for a derivation of this, seehere).

You may find it hard to accept this idea that the total energy of the universe is zero. This is only

possible if we consider gravity to provide "negative energy". This is described well in this article

by Filippenko and Pasachoff: "You can easily see that gravity is associated with negativeenergy: If you drop a ball from rest (defined to be a state of zero energy), it gains energy of

motion (kinetic energy) as it falls. But this gain is exactly balanced by a larger negative

gravitational energy as it comes closer to Earth's center, so the sum of the two energies remains

zero."

Stephen Hawking also explains this principle clearly in this extract from his book "A Brief

History of Time": "The total energy of the universe is exactly zero. The matter in the universe ismade out of positive energy. However, the matter is all attracting itself by gravity. Two pieces of

matter that are close to each other have less energy than the same two pieces a long way apart,because you have to expend energy to separate them against the gravitational force that is

pulling them together. Thus in a sense, the gravitational field has negative energy. In the case of

a universe that is approximately uniform in space, one can show that this negative gravitationalenergy exactly cancels the positive energy represented by the matter. So the total energy of the

universe is zero."Also see thisNew Scientistarticleby Lawrence Krauss.
http://www.ipod.org.uk/reality/reality_small_world.asphttp://www.ipod.org.uk/reality/reality_small_world.asphttp://cr4.globalspec.com/blogentry/1545/The-Hamiltonian-A-Qualitative-Analysishttp://www.ipod.org.uk/reality/reality_gravitation.asphttp://www.ipod.org.uk/reality/reality_wheeler_dewitt.asphttp://www.ipod.org.uk/reality/reality_wheeler_dewitt.asphttp://www.ipod.org.uk/reality/reality_universe_from_nothing.asphttp://www.ipod.org.uk/reality/reality_universe_from_nothing.asphttp://www.ipod.org.uk/reality/reality_free_lunch.asphttp://www.ipod.org.uk/reality/reality_free_lunch.asphttp://www.ipod.org.uk/reality/reality_free_lunch.asphttp://www.ipod.org.uk/reality/reality_small_world.asphttp://cr4.globalspec.com/blogentry/1545/The-Hamiltonian-A-Qualitative-Analysishttp://www.ipod.org.uk/reality/reality_gravitation.asphttp://www.ipod.org.uk/reality/reality_wheeler_dewitt.asphttp://www.ipod.org.uk/reality/reality_universe_from_nothing.asphttp://www.ipod.org.uk/reality/reality_universe_from_nothing.asphttp://www.ipod.org.uk/reality/reality_free_lunch.asp


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In order to convert the Hamiltonian to its quantum mechanical form, we have to consider the

Hamiltonian as representing the total energy. We can then use the quantum mechanical formula

for energy which we derived previously on the Quantum Casinopage:

As this is an energy operator, we need something for it to operate on. So we have had to againintroduce this strange concept of a wavefunction, , extending through space. So another new

concept must now be introduced: the wavefunction of the universe. The principle of the

"wavefunction of the universe" imagines the entire universe as a single object, a quantum object.

Michio Kaku explains it well: "When the universe was born, it was smaller than an electron,which is a quantum object that can exist simultaneously in many states. So the universe must

also be a quantum object and exist in many states."(seehere). So we can apply our Hamiltonian

operator to our "wavefunction of the universe":

This is the Wheeler-DeWitt equation - a sort of Schrdinger equation for the gravitational field. It

is the most famous equation in quantum gravity.

(A variation on this canonical quantization of gravity eventually leads to the recent, cutting-edge

theory ofloop quantum gravity - see thisPhysics World article by Carlo Rovelli, or Lee Smolin'sScientific American article Atoms of Space and Time).

Time and the Wheeler-DeWitt Equation

There's something remarkable about the Wheeler-DeWitt equation, and it can be seen if we

expand the Hamiltonian operator:

Or, expressed in words, the rate of change of the state of the universe with respect to time is zero.

The universe isn't changing with time! But we look around us and we see things changing all thetime: people are walking, birds are flying. So is the equation wrong? Well, no. What the equation

is once again telling us is that there is no external time reference by which we can measure the

progress of time within the universe: there is no clock outside the universe! As Andrei Linde

explains: "The notion of evolution is not applicable to the universe as a whole since there is no

external observer with respect to the universe, and there is no external clock that does notbelong to the universe"(see page 25 of Andre Linde's paperInflation, Quantum Cosmology and

the Anthropic Principle).

Therefore, the Wheeler-DeWitt equation agrees with our earlier analysis of the nature of time

because it suggests a block universe model in which all of time is laid-out (just as the space

dimension is laid-out), and all times are equally real: there is no special "now", no distinction
http://www.ipod.org.uk/reality/reality_quantum_casino.asphttp://www.ipod.org.uk/reality/reality_quantum_casino.asphttp://www.villagevoice.com/arts/0216,edlim,33954,12.htmlhttp://www.villagevoice.com/arts/0216,edlim,33954,12.htmlhttp://www.ipod.org.uk/reality/reality_rovelli.pdfhttp://www.ipod.org.uk/reality/reality_rovelli.pdfhttp://www.ipod.org.uk/reality/reality_smolin.asphttp://arxiv.org/abs/hep-th/0211048http://arxiv.org/abs/hep-th/0211048http://www.ipod.org.uk/reality/reality_quantum_casino.asphttp://www.villagevoice.com/arts/0216,edlim,33954,12.htmlhttp://www.ipod.org.uk/reality/reality_rovelli.pdfhttp://www.ipod.org.uk/reality/reality_smolin.asphttp://arxiv.org/abs/hep-th/0211048http://arxiv.org/abs/hep-th/0211048


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between past and future. In fact, "past" and "present" do not exist - the movement of time is

considered to be just an illusion of human perception.

Free Will in a Block Universe

Some people have suggested that the block universe model is incompatible with any notion offree will. This, they would say, is because the future appears to be set-in-stone in the block

universe model, so we are never at liberty to change it by our choices. I would disagree with this

reasoning as I believe it shows a fundamental misunderstanding of what the block universeimplies. We will see that the block universe is completely compatible with the notion of free

will.

The misunderstanding arises because the notion of free will is so poorly defined. We all think we

know what "free will" is, we have a feeling, but it is very hard to write down what the phraseactually means and implies. In the absence of a satisfactory definition, I am going to define "free

will" in what I believe is the best and most accurate description:

Free will is defined as the ability to make decisions.

(This appears to be the same definition of free will used by theCompatibilism school ofphilosophy which states that you have free will if you feel free to make a conscious decision

without, for example, someone forcing you to make a particular decision by pointing a gun at

your head. Hence, the Compatibilists believe you can have free will even in a deterministic

universe. But I am taking the Compatibilist view further by saying that not only can you havefree will in a deterministic universe, but you can also have free will in a deterministic block

universe).

So what do I mean by "making a decision"? It means the ability to consider a range of manypossible courses of action, and to select only one course of action from that range of possibilities.To all intents and purposes, I think that is a reasonable definition of free will.

This definition of free will is completely compatible with the block universe model. The key

thing is that only one course of action results when we make a decision. There is only oneoutcome. There is only ever one stream of events. For example, the sequence of events when we

come to a fork in the road might be:

EVENT 1) You walk along the road and come to a fork in the road.

EVENT 2) You decide to turn to the left.

EVENT 3) You continue your journey along the left road.

This is just a sequence of three events, and that's all the block universe is: a sequence ofsuccessive events. So these three events can easily be incorporated into the block universe

model.
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In the block universe model, events are unchanging and "frozen-in-time". But that does not mean

that those events do not represent the expression of free will. For example, when we look back

into the past we consider those past events to be "frozen", and nothing could change thoseevents. However, we might also remember some of those past events as representing moments

when we made decisions, i.e., expressed our free will. So the notion of free will is in no way

incompatible with the block universe "frozen-in-time" representation of unalterable events.

In his bookThe Fabric of Reality David Deutsch suggests that some sort of "branching"multiverse universe is required to account for free will and the human decision process (see the

New Scientistarticle Taming the Multiverse). In Deutsch's model, when the human comes to a

fork in the road, the universe (and the person) splits into two different universes so the person iscapable of travelling down both roads. Deutsch appears to think that this is the only way that the

human can have free will. But Deutsch is ignoring the fact that a decision can only ever have oneoutcome, so only one road is travelled after the decision is made (i.e., after the human expresseshis free will). This is therefore completely compatible with a single block universe: no branching

"multiverses" are necessary.

Back to the main page

Comments

Comments are now closed on this page.

I've been trying to wrap my mind around all these concepts, QM, relativity, the theory of

everything, etc, for a while now, reading everything that I could find (which is just a smallfraction of what's out there), and everytime I think I come close to some understanding, I

stumble upon something else that throws me right back to square one. Tonight it is the blockuniverse concept that did it again.

So I have a few questions, and I ask you to go easy on me :) because I got to the point when I

walk around the apartment talking to myself :):):)First of all I think that all the physics of the 20th century, beginning with Einstein's special and

general relativity, then quantum mechanics and all the thories that try to unite them are

absolutely counterintuitive.(Although they amaze and fascinate me). But that happenedthroughout the history after all, there were many "crazy" concepts that we ended up accepting as

real. So hopefully I will end up understanding all this :)I need some help though...

1. It is stated here that: " It is true that the universe appears to change for an observer within theuniverse, as there is a time dimension defined within the universe. So it is valid to considerobjects within the universe changing with time. But there is no clock outside the universe, so the

"external" view of the entire universe structure can never change with "time".

For me, this statement contains a contradiction: since we are all whithin the Universe, how canwe tell what is or what is not outside the universe? Since we are whithin the universe and it is

valid to consider objects changing with time, isn't this block universe actually a view from

outside the universe?
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2. How can we leave all human bagagge and sensations at the door, while we are still human?

And since the time arrow is a result of a trick that our mind plays on us, how do we know that for

instance the block universe is not actually another trick of our mind? What makes one conceptmore real than the other?

3. From the perspective of an unchanging block universe, are our actions of any importance and

consequence? (OK, this is more a philosophical question, but then again, isn't all this very muchlike philosophy?)

4. Going back to QM, I was trying to understand the effects of it (lets assume now there are

causes and effects in the univers) on us, human beings, since we are all built out of atoms andtherefore particles that are in superpositions. Can QM have a role in our very way of looking at

the universe and everything within it, including time? Maybe our answers will come when we

eventually understand our brains, and the illusions or realities these brains object us to?

Not long ago I came across Edgar Cayce and Akashic records, which actually sustain the idea ofa block universe, where there is no past, no future. But since this man gave all the "predictions"

under hypnosis, could it be possible that everything is encapsulated in our brains?

Uff, it's a wild world:) -Monica Garliceanu, Winnipeg, Canada, 24th March 2009

Hi Monica, that's a lot of very interesting questions. I'm glad it has got you thinking. Firstly, didyou read Paul Davies's excellent article on the Block Universe:

http://www.ipod.org.uk/reality/reality_mysterious_flow.asp I really can't explain it better thanthat, but I will try to answer your questions.

1) Yes, that extract was not very clear and I have modified the text - thanks. The passing of timeis an illusion for objects (such as humans) within the universe. The block universe is the true

picture in which all times are equally real.

2) I think from our very earliest years we accumulate human "baggage". For example, we aretold in school that "times passes". I think maybe we can get rid of our human baggage by

pretending we are children again, with no preconceptions of how the world works.

3) I have just added a section to the end of the main article called "Free Will in a Block

Universe" which hopefully explains how we can still make decisions (i.e., express free will) in a

block universe. So our actions and decisions are definitely of importance and consequence.

4) Yes, quantum mechanical effects definitely play a role in making it appear as though time is

passing: this is the "quantum mechanical arrow of time". Again, see my "Arrow of Time" page

for a discussion of this.

Thanks a lot, Monica. Keep thinking! -Andrew Thomas, 24th March 2009

These models do not explain why the Second Law of Thermodynamics is not consistent - bothlife and gravity cause entropy to decrease. Further - they assume that the BB and the expanding

universe are correct. This is a house of cards as they are interdependent - if one fails then so does

the other. For a simpler explanation for the mechanism of time go to:http://www.toequest.com/forum/toe-theory-articles/3578-the-dance-shiva.html - Unknown, 31st

March 2009

Hi, thanks for your comment. Sorry my anti-spam software filtered-out your name. If you want

to post your name again, I can correct that.
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But life does not cause entropy to decrease - I'm afraid we all go wrinkly as we get older. As far

as gravity is concerned, gravitational entropy seems to work in the opposite way to normalentropy. I will quote Roger Penrose from his book "The Road to Reality": "Gravitation is

somewhat confusing, in relation to entropy, because of its universally attractive nature. We are

used to thinking about entropy in terms of an ordinary gas, where having the gas concentrated insmall regions represents low entropy, and where in the the high entropy state of thermal

equilibrium the gas is spread uniformly. But with gravity, things tend to be the other way about.

A uniformly spread system of gravitating bodies would represent relatively *low* entropy,whereas *high* entropy is achieved when the gravitating bodies clump together". See

http://www.ipod.org.uk/reality/reality_gravity_entropy.asp -Andrew Thomas, 31st March 2009

But the question reamains that there is a 50-50% chance of everything existing than nothing

existing, so some factor must exist that swayed the balance to existence. This is where i believein God. Maybe not as religeon sees it, but omnipotence must be that factor. Plese submit your

opinions on this. Very thought provoking site, though. Thanks Andrew Thomas!

- Shaun Goold, 2nd April 2009

One more thing. If time is equaly real, then using the other three dimensions in some way, surelya beam of light has no particular speed. (if time does not progress or regress, then S=D/t does not

apply) - Shaun Goold, 2nd April 2009Hi Shaun, thanks for your comments.

Regarding existence, and your 50/50 idea, we simply don't understand existence and "Why isthere something rather than nothing?" Still, that doesn't stop us thinking about it! I don't really

see we can assign a 50/50% probability to existence as you suggest: it might be that there is a

100% chance of existence (so we HAD to exist), or a 0.00001% chance of existence and we just

got lucky! We just can't tell.

As far as the speed of light is concerned, the movement of light is no different from the

movement of any other object as regards this discussion about the block universe. I think you arethinking about the fact that time does not pass for a photon due to relativity:

http://www.physicsforums.com/archive/index.php/t-211186.html -Andrew Thomas, 3rd April

2009Hi, Andrew:

Let me involve myself in this your wonderful web site. I'll try to be concise. It's curious that in

our world there only one universal movement exists: oscillatory movement. Earth, Moon, Sun

and galaxies all them have a movement that can be treated as oscillatory, as we know sinceCollege. Rectilinear movement is an exception even in Earth. In the microworld it's a common

transformation as well. This is just what the clocks count. And it's curious in our universe exists

another general phenomenon also: the increase of entropy, that tell us about the Arrow of Time.In my mind for evolution both are conditions needed. Let's see the simple oscillatory movement

(harmonic)

simple, but the must essential-. From school we know that along a semicycle it passes from afree forces point to an intermediate tendency of centralization point, then to a maximum

centralization of forces point in the extreme and then to another decentralization of forces point.

The first point is completely the opposite of the third and so do the second point and the third.

It's the natural way of transformation. But besides there is the increment of entropy, that finally
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stops the pendulum. If there is not an increment or decrement of entropy it will be a

transformation but not evolution, everything will returns to its origin. This increment is not only

a bad thing, because of it exists evaporation, mixtures, amalgams; you can't recombine an egg ifit hits the floor but thanks to this you can crack the egg to eat it. I can suppose a world where

along its oscillations entropy decrease and there it will be evolution as well, but if entropy is

constant along the oscillations then there is no evolution. It's the case of the electromagneticwaves in vacuum and for that its velocity is absolute, doesn't evolve. A particular kind of

*oscillation plus entropy* (what maybe is bad called negentropy) occurs in biological systems,

where a whole unique is constructed from the cells aggregations dividing, uniting likeoscillations-. Also in thinking, who goes from analysis to synthesis to analysis, etc. And, finally,

in the successions of civilizations throughout the History as we have described in The tiny

Leonardos smile, mentioned in a commentary I'd done some steps up in this same page. It also

explains the deep condition of beauty in the art masterpieces could be done for literary workstoo- throughout the History. It's curious. Alberto Prez-Delgado. Havana. Cuba.

-Alberto Prez-Delgado, 23rd April 2009

Hi,Andrew. A few explanations. In my haste I wrote that the second point is the opposite of the

third, its wrong, is the opposite of the fourth. Also,I misprinted: bad named, I should wrote: itswrong -or incorrectly- named negentropy. Its necessary to explain that in the context of my note

when I say that the increment of entropy finally stops the pendulum its not necessary refers tofriction because heat is not like mechanical energy, an energy we can transform totally in other

forms of energy, when the pendulum becomes warm we cant use it in restore the movement,

precisely caused by the Second Law of Thermodynamics and heat is the only form of energy thatdoes this kind of thing. Its curious. -Alberto Prez-Delgado, 28th April 2009I studied Experimental Psychology at Cambridge in the early 'fifties with Richard Gregory as my

tutor; the subject had only just been moved from the 'woolly' arena of association with politics

and economics to become a part of the Natural Science Tripos. We were thus some of the firststudents to treat psychology with the rigour of a scientific subject rather than as the somewhat

disreputable basis for 'psychoanalysis'.

This fact, I think, affected my thinking about science as a whole over the rest of my life (I was

actually studying medicine at the time).

In particular, I now see, it has made me impatient with physics, which pretends -- I use the world

in its old-fashioned sense -- to describe the universe to us. I could never understand how this

could be so, since physics almost studiously avoided (and still avoids) the mind as an entity for

study.

I do understand, of course, why this should be the case; the 'scientific method' -- which I find

admirable in itself -- is largely unsuited to framing hypotheses (which need to be falsifiable byway of observation) about the nature and attributes of the mind. If I may put it light-heartedly:

the consequence of this has been that physics despises psychology as being the province of

artists who would like to fancy themselves as scientists, while the humanities despise physicistsas mere mechanics who should stick to designing better mouse-traps and leave the greater

questions of 'How?' and 'Why' to philosophers who (being gentlemen and ladies) are better

educated for the task.


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I always saw that this was nonsense, but could never persuade either side to take much of an

interest in the other's area of expertise -- an area which in the case of the mind is, as a matter of

sheer fact, poorly examined, perhaps because it requires little in the way of expensive particleacccelerators and so forth. In any case, I have always been more saddened by the refusal of

physics to study the mind than by the inability of psychologists (including myself) to get a fair

grip on the mathematics of physics.

This has been the state of affairs for several centuries. It cannot, though, continue thus for much

longer. Descartes was right; the only way we know we, and the universe, exist is by way oflooking at what we experience with our minds, there being nothing else we can directly examine.

All of physics, therefore, is carefully and expertly constructed (but wholly by inference) from

what we can observe, namely, our mental experiences; and, now that we think of computers as

able to reason and in some sense to 'observe', the interface between the immaterial mind -- ofwhich physics is justifiably leery -- and the material world has become vital to our study if we

are to progress in making sense of the Way Things Are as a whole.

We cannot treat matter and mind as conveniently separate entities any more; something physicalis happening where they meet, and we need to be able to describe what it is. -Martin

Woodhouse, 23rd May 2009Thanks a lot for that, Martin. A super contribution. Personally, I just stay clear from ALL

questions about consciousness and the mind. For a start, we seem to have such a poor

understanding of it. But secondly, my gut feeling is that it consciousness as such does not play afundamental role in the universe (sorry!). I just feel it's an emergent property when billions of

neurons are firing at the same time.

I've always had an interest in John Searle's Chinese Room:http://en.wikipedia.org/wiki/Chinese_Room. I think it's the best thought experiment for

revealing insights into intelligence and consciousness. I think it shows that if any AI system is to

be considered "conscious" then it has to be sufficiently complex to contain internal models ofitself ("self-awareness"). Simple pattern matching of inputs and outputs is not enough - it has to

contain that internal model of itself. I think when it achieves that self-awareness, it is conscious.

That's just my gut feeling on the subject. Thanks again. - Andrew Thomas, 23rd May 2009Hi Andrew, greetings from the US; I am loving your articles and the comments as well.

Ever since I was about 19 y.o. (that's 34 years ago, I think) I've had a couple of problems with

'block universe'-type views of reality.

First, when we apply the logic of 'block universe' as a logical formalism at every level, then,

because all logic is time-directional/evolving, we MUST wind up producing such statements as'what I say has no meaning,' 'rationality is, rationally speaking, a delusion,' 'the idea of rational

discourse is a red herring', 'the idea of red herrings is a red herring' and so on--versions of the

liar's paradox. If time is an illusion, so is logic. In a block universe where evolution does notexist there can be no valid development of an argument, no experimentation, no meaningful

statements about errors, etc. In a REAL block universe all my endeavors are absurd, all my goals

red herrings, and so on. But when we are so obviously attached to all of our time-directional,

purposive, meaning-manipulating endeavors, including science and experiments and Internet
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comments and so on, it seems a little hasty to throw a logic bomb like that into the mix--and self-

defeating in a potentially serious way. Since we obviously CAN'T and WON'T adopt such a

philosophy for our everyday lives, why make ourselves so absurd, even in the abstract? In otherwords, no one REALLY believes that, in the sense of acting on it; they just SAY it.

A second problem I have is the blitheness with which some people seem to make such statementsas 'there is nothing outside the universe', 'there is no clock outside the universe', 'there is no

external observer', and so on. While for certain purposes (oops...that's certain illusory purposes)

it makes sense to think of the universe we observe as a closed 'eternal' system, where is thereANY evidence that it is actually like that and not, for example, one of a pair of 'entangled'

'quantum' systems [to use an analogy], or an S3T bubble inside a universe of different

dimensions, or who knows what?

So again thanks Andrew, and if anyone can show me the errors in my logic (see shorter

statements below) I would be grateful...oops, I would think I was grateful...um, I would have the

illusion of thinking I was grateful...ah, shoot!

Love ya.

Contention i. Assumption of the absence of time-directionality in the 'real' universe reduces ALL

linguistic, rational and scientific statements, (including 'time-directionality is an illusion') to

absurdities, or 'red herrings'.

Contention ii. There is no evidence AT ALL for such statements as 'there is nothing/no clock/no

observer outside the universe', and it is weak thinking to base 'scientific' descriptions of reality

on such unfounded, scientifically untestable 'maxims'.- deWitt, 16th October 2009

Hi deWitt, thanks for a great comment (I'm lucky that people do post great comments on this

site). I'm pleased to tell you that the block universe model is completely compatible with the waywe live our lives and changes nothing about our "logic" or our "goals" (of course, if the block

universe model was not compatible with our experiences then it would have been rejected as an

inaccurate model of the world).

Just as an example, let's consider your statement "all my endeavors are absurd, all my goals red

herrings". I can reassure you that the block universe model is completely compatible with a

universe in which people make decisions and those decisions have outcomes. This is becauseeach decision only has ONE outcome. I have just added a new section to the end of the main

article called "Free Will in a Block Universe" to explain how free will is compatible with the

block universe model precisely because any decision only has one outcome.

And I'm pleased to tell you that "logic" can also be incorporated into the block universe model in

a similar way. You say "time is an illusion". No, time exists, it is only the FLOW of time whichis an illusion. The block universe changes nothing about how we experience logic and time. The

block universe model is not absurd in any way, in fact it is absurd to suggest that time flows at a

certain rate (as then we would have to ask "How fast does time flow? One second per second?" -

a clearly absurd statement).


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So there MUST be a "now" moment; even if the points in time in which I have finished typing

this post already exist, I can at least say that I have not experienced it yet because "now" I am

still typing this post.

The question is, why is 23rd March 2011 NOT "now"? The fact that it is not makes it apparent

that there IS a now, even if "now" just a perception of movement through a dimension in whichall moments "before" and "after" the moment called "now" already exist.

I'd like to add that the reality of a changing "now" moment is apparent in the fact that a "past"and a "future" can ONLY be defined in relation to "now".

In other words, "now" could seem to be defined as the point in time before which you are able to

remember and afterwards you are not.

This seems no different than defining the points along a road ahead of you and behind you; all

the locations along that road exist simultaneously...but you can only define what's "ahead" of you

and "behind" you along the road in reference to "here", or your location on the road.

That you are NOT able to remember tomorrow may not necessarily mean that tomorrow hasn'thappened yet, but it DOES mean that tomorrow is not "now". - Taurus, 16th October 2009

Hi Taurus,

You make some very good points, and you're right: it is surprising that nobody has brought thisup.

I'm going to start by emphasising that there is no special "now" point in time, unlike your

suggestion. All times are equally real and there is nothing to identify any particular point asbeing "special".

But surely, you might protest, we know that the time "now" is special because it is the pointwhen all the past is in our memory and all the future is unknown to us. Surely there is a clear

division, with time being divided into "past" and "future" by the "now". That is the point you are

making.

Well, the answer is that *every* point on the timeline is exactly the same. No matter which point

on the timeline you might select, you would always feel like that is the "now". No matter which

point you might select, you would always be able to remember the past and unable to know thefuture.

So the point is, no matter which point you pick, you would always feel the same you wouldalways feel like that is the "now" point. So (I look at my clock) right now it is 3pm on Friday the

23rd October 2009. And it feels like "now" to me. So if I could see the whole timeline I would

see myself on Friday the 23rd October 2009 feeling like it is now. But I could also see myselfagain at a later point on that timeline (all points in time are equally real) a year from now looking

at my watch and feeling like it is "now" as well.

The timeline is just a long line of dates and times and I exist at each date and time feeling like it


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is the "now". So to answer your question "Why am I experiencing THIS particular point along

the time axis (typing out a post on this website) and not another" is that no matter what point you

might pick in time, you would always find yourself feeling like it is "now". There is nothingspecial about this particular point you would feel that same way whichever point you picked.

Thanks a lot for an excellent question. -Andrew Thomas, 16th October 2009Andrew, in your post where you state that to measure how fast time passes "we would need some

sort of second measuring clock *outside* the universe, outside of time itself, and such a clock

could never exist."

You're forgetting here that Einstein solved this puzzle a bit ago. Both the speed of light and

alternate frames of reference are perfect yardsticks for measuring the flow of time.

Scientists have measured differing flows of time for astronauts (slower aging) with atomic

clocks, and for our entire GPS system to work, compensations in the calculations must consider

the changes in the flow of time as different sats whirl at different relative speeds to our locations.

Now is there a master flow of time that all of these "slower speeds" of time are relative to?Perhaps... and maybe (maybe!) THAT can only be known by having a measuring stick outside of

our dimensions. However quantum theory and gravity are not well understood and these may in

fact contain such a measuring stick.

From the perspective of earth, a person traveling by at the speed of light would be practically

motionless because time would be passing so slowly. Of course from that speedy guy's

perspective, the time on earth would be flying by incredibly fast. This is one reason among manywhy achieving the speed of light itself (within our dimensional universe) is probably impossible

for a physical being. -MarkL, 17th October 2009

Hi Mark, good question. Yes, if we put an astronaut into space then we find that he ages at aslower rate that someone on earth. So you could possibly say that "time passes at a slower rate

*relative* to someone on earth". So you make a good point that there can be *relative*

differences in an apparent flow of time.

However, this does not answer the question "How *fast* does time pass?" As we all appear to

feel a flow of time, precisely how fast is that time moving? (This is the "master flow of time" to

which you refer). If we imagine the "now" point to be a pointer sliding on a scale of events, a"moving now", how fast is that pointer moving?

Quantum theory and gravity doesn't come into it. A simple philosophical argument (it is absurdto say that "time flows at one second per second") shows that *time itself* does not move, and it

is illogical to suggest that it does. It's just a feeling.

You mention Einstein, so let's finish with a quote from Einstein about the illusion of the "moving

now" (which is included on the "Cosmic Universe" page of this website): "People like us, who

believe in physics, know that the distinction between past, present, and future is only a

stubbornly persistent illusion." -Andrew Thomas, 17th October 2009


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Everything is always measured in terms of something else. So measuring time in reference to a

baseline makes perfect sense.

For example we could postulate "Earth-Time-Flow" as our baseline. With that agreement,

relativistic effects would enable us to measure both faster and slower time-flows.

The fact that time may be an illusion doesn't preclude the measurement of it. Most interpretations

of Quantum mechanics indicate that mass itself is an illusion... yet my ruler, speedometer, and

GPS work quite effectively, because at the illusion level there's an obvious baseline and sharedagreement.

What's more, we know what both the minimum and maximum timeflows are (time stops as you

approach the speed of light which has a known max, using calculus limits), giving us a gradientscale or "time speedometer."

I disagree that the flow of time isn't measurable. You're looking for an external yardstick, but one

isn't necessary just as one isn't necessary to measure distance. When we say a mile is a mile, howdo we know that a mile on the other side of the earth isn't "stretched" by some extra dimensional

force? We don't! In fact many physicists believe that gravity is the effect of the stretching ofspace-time.

The point is, that you don't need an external reference to compare or measure things. You justneed to agree on a baseline. An inch is about...*holding fingers up* that long.

We also don't need an extra-dimensional reference to measure how fast time-flows. A second is

about "thaaaat" long. Now we can look at others moving at relativistic speeds and clearlymeasure that a second is longer or shorter for them.

Thus, even today, we can (and have) measured the flow of time. -MarkL, 20th October 2009Hi Mark, yes, we can absolutely measure time using a clock, for example, and we can say things

like "This time is longer than that time". Time is just another dimension, like length, so yes, we

can measure it. But the question we are considering here is the question of the moving "now". Dowe have a "now" point which is actually moving, or are all times equally real?

Measuring lengths of time is a very different thing from saying "How fast is the 'now' point

moving? How fast is time itself moving?" We can measure lengths of time without needing tohave a moving 'now' point at all.

You suggest we could send an astronaut close to the speed of light, and then we would find theclock of the astronaut has measured less time than our clock, yes, absolutely. But that is all

possible without needing a moving "now". That is possible by just having fixed events ("We read

our clock", "the astronaut reads his clock") in a fixed spacetime structure. For a great explanationof this, see the section "How Time Doesn't Fly" in Paul Davies's great article:

http://www.ipod.org.uk/reality/reality_mysterious_flow.asp

So, yes, by using a clock we can measure a time duration, a *length* of time. But what we are
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not necessarily measuring is the *speed* that something (the "now" point) is moving.

You could attempt to convert that time duration into some sort of measure of speed of a moving"now" point, and calling it a measure of the speed of the "flow of time" (as you suggest), but

there is really no justification in physics for doing that (other than the emotional feeling we have

of the "now" moving).

(You make a good point that if there could ever be an *absolute* baseline "time flow" then we

could consider different rates of time passing relative to that baseline. I actually cover this in thesection "Spacetime in a Simulation" on the Living in the Matrix page:

http://www.ipod.org.uk/reality/reality_simulated_reality.aspIn that example, a "clock outside the

universe" was provided by the external simulating universe. However, we don't have access to

such an absolute baseline).

It's interesting you mention length, and the problem of finding an absolute yardstick. You might

enjoy Julian Barbour's article "The Non-Expanding Universe":

http://www.fqxi.org/community/articles/display/117which considers eliminating absolute sizeand the universal clock.

Thanks a lot, Mark. -Andrew Thomas, 20th October 2009

Well, I guess we'll disagree on this one. To me if I can see that an atomic clock on an astronaut's

space ship is going slower than mine, and that his now is progressing at a measurable, slowerrate, I can indeed measure the flow of time. I can state that his flow, or his time rate, or the speed

with which his now is moving forward is different than mine... and can measure the difference in

our flows quite precisely. -MarkL, 24th October 2009

Hi Mark, let's consider this "flow" of time thing:

Your proposal is that someone on earth can measure the "flow" of time and use that as a standard

so that everyone else in the universe can measure a "flow" of time relative to the earth standard.But in order to achieve this - in order to set a standard "flow" of time - it has to be possible for

*someone somewhere* to measure the "flow" of time, i.e., it has to be possible for someone

somewhere to measure the speed at which *time itself* moves.

So ask yourself this, Mark: how would *you* measure the speed at which *time* moves? Yes, it

is possible to get a stopwatch and measure the speed at which light moves between two points.

But that's not measuring the speed at which *time* moves, that's measuring the speed at which*light* moves.

Using a stopwatch it is possible to measure the speed at which an object moves with respect totime, but it is not possible to use a stopwatch to measure the speed at which *time itself* moves

with respect to ... what?

So it's not possible for the person on earth to set the standard speed for the "flow" of time

because it is impossible for *anyone* to measure the flow of time using a stopwatch.

I can strongly recommend getting hold of a copy of Craig Callender's book "Introducing Time"
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which explains this all much better than I can. Here is a four-page extract:

http://www.ipod.org.uk/reality/reality_introducing_time.asp

(In that extract, Callender refers to the block universe model as the "tenseless" theory, with your

proposed model being the "tensed" theory). The book is well worth a few quid of anyone'smoney.

I suspect we're going to have to agree to disagree on this one, Mark. Thanks for all yourcomments. -Andrew Thomas, 25th October 2009

Andrew, thank you for your thoughtful reply....

...but I still can't wrap my head around this concept.

You're right to point out that every single point on the timeline would be percieved as a "now"

moment....but I don't see how this in and of itself is particularly convincing as an argument

against a "now" moment because *the same would STILL be true if there WAS a moving "now".

If there was a moving now moment, you would recall each point along the timeline as "now" the

same exact way you recall your location along a road you are moving along as "here". It would

seem fallacious to conclude that no "here" location exists merely because you always perceivedyourself as "here" along every point on the road.

From an external reference point, you could look back on every moment in the past (or future) as

"now" the same way you could look at every location of your vehicle along a road as "here", butthat doesn't make "now" or "here" not special either; "here" is the point along the road before

which you have already traveled and after which you have yet to travel. If you are actually

moving along the road from point A to B, then "here" necessarily changes.

"Here" and "now" can also be quantified as reference points; If you were moving from point A to

B, "here" could be ~70km from point A. "Now" could be ~13.7 billion years from point A, couldit not?

....and I ask again, if the "flow" of time is an illusion caused by our inability to remember the

future, then how can you define the future without a "now" moment? How can you delineatebetween the past and future without the "present"? As I said, even your picture frame example

shows "The Present" clearly marked.

It's not difficult for me to grasp that the flow of time would be an illusion if time were a

dimension that we merely experience in a particular way. But it *IS* difficult for me to grasp

that my perception of that dimension is not akin to traveling along the rest of the threedimensional world; a span of time may be laid out the same way a span of road is, but I delineate

between the "past" and "future" using "now" the same way I delineate between "behind" and

"ahead" using "here". "Here" is just as real and useful as "now" in this sense, is it not? - Taurus,

28th October 2009
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Hi Taurus, thanks, this isn't an easy thing to "get one's head round" at all. And I don't think the

majority of general amateur physics readers are even aware of this fundamental principle, which

is surprising considering how crucial the concept of time is.

Firstly, you're absolutely right when you say "the same would STILL be true if there WAS a

moving now" - the end result would be exactly the same as the block universe model. In theexample you provide about moving along a road, yes, you're right, the end result is exactly the

same as if you are existing at every point in the road.

So, you might ask, why should the block universe model be favoured? Well, there's actually a

few reasons.

Firstly the laws of physics we have discovered (such as Newton's laws) do not include anymention of any "now" moment - no reason why, say, the current year 2009 should be preferred

over 1975, for example. Even though the current year feels very special to you, as far as the

equations are concerned it is not special at all and is treated just the same as 1975. The "now"

just doesn't figure in the equations anywhere. In fact, the only reason why we seem to feel theneed for a "now" is because of the way we "feel" - we "feel" like the time now is special, and that

that now is moving. So apart from an emotional response, there is no need for a "now" in knownphysics.

Secondly, there are some strong philosophical arguments against the moving "now", such asMacTaggarts's "Unreality of Time" argument (which I find quite hard to understand):

http://en.wikipedia.org/wiki/The_Unreality_of_Time

and D.C. Williams's argument "How fast does time flow?" which is much easier to understand:

http://www.ipod.org.uk/reality/reality_introducing_time.asp

And then, most seriously, Einstein's theory of relativity appears incompatible with the moving

now according to the Rietdijk-Putnam argument (see the idea of Hilary Putnam in that previouslink). It is simply not possible to cling to the idea of the moving "now" once we introduce

relativity.

As to your objection that we cannot identify "past" and "future" without having a "now" point Iwould just like to quote Einstein again: "People like us, who believe in physics, know that the

distinction between past, present, and future is only a stubbornly persistent illusion."

(Regarding my diagrams which appear to show a "now" moment, yes, you're right, that's not

great - that's inaccurate. But it would be extremely difficult to illustrate the idea of the lightcone

without using the conventional idea of time with a "now" point - I'd basically have to draw a longseries of light cones with lots of different "nows", and the diagram would look a mess. So as you

say a the end - it is useful to talk about a "now" sometimes! But in strict physics terms it is very

dubious.)
http://en.wikipedia.org/wiki/The_Unreality_of_Timehttp://www.ipod.org.uk/reality/reality_introducing_time.asphttp://en.wikipedia.org/wiki/The_Unreality_of_Timehttp://www.ipod.org.uk/reality/reality_introducing_time.asp


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Thanks a lot. -Andrew Thomas, 29th October 2009

One more thing Andrew!

Doesn't the Heisenberg Uncertainty Principle imply that the "Block Universe" must not be an

accurate description of time if the future is indeterminate?

You also didn't mention anything about time being quantized in Quantum Gravity, Chronons, or

the general implications of the idea that time may not be continuous and how that would relate tothe "Block Time" concept. - Taurus, 29th October 2009

Hi Taurus, yes, you're right that the block universe model ignores any quantum mechanical

effects - it merely deals with the implications of relativity. For example, the argument of Hilary

Putnam shows that the tensed theory is incompatible with special relativity - he doesn't refer toquantum mechanics at all.

However, the argument of D.C. Williams ("How fast does time flow?") does not refer to either

relativity OR quantum mechanics. In fact, it doesn't depend on any physics at all! Instead, itseems to reveal a fundamental flaw in the human intuitive model of time. (Basically it says that

"time itself" cannot move because it cannot move with respect to time. How fast is time moving?One second per second? That's a nonsense).

So there is a logical flaw in the tensed theory of time which does not involve relativity orquantum mechanics at all. The human model - which is so widespread - has a simple logical

flaw. I don't see how it can be correct. No QM or relativity required. -Andrew Thomas, 29th

October 2009

Thanks again for your answer, Andrew.

I have *NO PROBLEM* with a universe in which the "future" (and all of my actions therein) is

essentially already written, indeed this was how I understood the implications of specialrelativity and how I explained it to friends for decades.

My apparent mistake was that I understood that time is laid out like the spatial dimensions of aroad along which a "now moment" progresses. Like a moving roller coaster car bound to a track

that's already built, no part of the track comes into existence as you move forward; the track, the

distance it traverses, and the directions in which it is laid out are already there, but the roller

coaster is MOVING along the track.

As I tried to explain, I thought that "now" was akin to "here" in the above analogy.

I thought that the rest of my life was laid out along the time dimension *but that I am MOVING

along that dimension* just as I move along the spatial dimensions.

As Andrew has elucidated (and as my own further research has confirmed), this appears not to be

to the case (at least as far our current understanding suggests). It appears that there is no "now"

moment and that I am NOT moving through a time dimension that is akin to the other spatial

dimensions. If I understanding Andrew correctly, I am not moving through time at all!


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Since I had understood time to be like a spatial dimension for many years, I'd assumed I was

moving through it the same way I was moving through the other dimensions. I'm very surprised,even startled, to find that this is apparently not the case... In fact, I'm having some difficulty

understanding exactly how it can be the case and it is my difficulty that troubles me, not the

concept itself.

....and I'm not *entirely* convinced that the block time concept is unassailable... Just dug up

something while looking for more (layperson-oriented) information on the topic: PhysicistsBrian Cox and Fay Dowker seem fairly certain that Einstein's view of spacetime is

fundamentally wrong... http://www.youtube.com/watch?v=iU90FeFSn2I&feature=related -

Taurus, 30th October 2009

Hi Taurus, that's a great video you found there - thanks. I have just added a trimmed-downversion of that video to the main article. I remember when I first saw that Brian Cox film last

year I thought that it was the first time the block universe model had been explained on TV.

However, Brian Cox's explanation is rather misleading when he shows himself travelling downthe road "into the future". If all times are equally real then he is *already* in the future - there is

no need for a moving "now".

In fact, it's not good that Brian Cox says in the video: "According to Einstein, the past, present

and future all exist", whereas in fact what Einstein said was: "The distinction between past,present, and future is only a stubbornly persistent illusion." Einstein certainly did not believe in

the distinction between past, present, and future, so that was a mistake by Brian Cox.

Then later in the video, those quantum gravity theories must be considered speculative, whereasthe block universe model derives directly from Einstein's theory of general relativity which has

been thoroughly experimentally tested. So the block universe model should be considered to be

the orthodox model, whereas Dowker's model should be considered to be speculative. Thanksagain for your contribution, Taurus. -Andrew Thomas, 31st October 2009
http://www.youtube.com/watch?v=iU90FeFSn2I&feature=relatedhttp://www.youtube.com/watch?v=iU90FeFSn2I&feature=related

Documents

Time in a Block Universe