Take Lucretian atoms, are they subject to time?

For how they arrange themselves, when they move and collide; they are subject to time; but this is in relation to other atoms, or to the place they themselves are in.

But atoms in themselves, and solely in respect to themselves, is that in time?

For they do not come into being, and nor do they pass away from being; and they aren't, in themselves, subject to increase or decrease [ie change]

Aristotles, De Caelo

We could say, they are in time; but whilst in time, they do not change; they have constancy; this I think, is the usual explanation.

But consider, would we get the same theory, if we supposed these atoms were not subject to time?

For if they aren't subject to time; then they can't come into being, and nor can they pass away, and nor can they increase or decrease.

  • Any concept of the "atom" faces the all the paradoxes of the mathematical "point" with zero dimensionality. If it is conceived as "in-itself" and relativized to nothing else, it is effectively "nothing" and nothing can be said about it. Time is an ordering process of relative parts or moments. It is one of the divisions or "concepts" that allows us to speak about the "universe" as if it too were an absolute totality, though we recognize this does not really make sense. – Nelson Alexander Feb 19 '16 at 22:51
  • @nelson Alexander: for sure; that's why Aristotle uses the concept of simple bodies instead; Even the Atomists took them to be extension less - otherwise they couldn't have shape; it's an interesting question when the idea of atoms as being extensionless arose; perhaps it's a conflation between Euclids point, and the Lucretian atom. – Mozibur Ullah Feb 21 '16 at 0:59

Time, space and spacetime are concepts we use in the context of physical theories to denote objects and events.

According to both the Special and the General Theory of Relativity, the basic concept is spacetime, a 4-dimensional manifold. Events are points in spacetime. They are determined by 4 parameters. After choosing a coordinate system we decompose these 4 parameters into 3+1 coordinates. They denote the space where the event happens and the time, when the event happens.

This fact can be taken as the meaning of the sentence "to be in time".

But immediately we have to face the fact, that decomposing the 4 parameters into space and time has a certain arbitrariness due to the choice of the coordinate system. Hence the absolute statement is "to be in spacetime". Only the latter is independent from the choice of the coordinate system. While "to be in time" is a relative statement.

When restricting to gravitational interactions every object which is "in spacetime" always moves through spacetime on a distinguished curve (geodetic line). This fact can be denoted as "being subject to spacetime".

As a consequence my answer to your original question is: Yes, everything, which is in spacetime, is subject to spacetime.

Of course there are things which are not in spacetime, e.g. laws of nature or mathematical objects or propostions.


Kant says time is something we impose on the things in themselves, which I suppose includes the atoms in themselves. It is thus conceivable that in such a Kantian world, the atoms aren't subject to time, it is only our minds which impose time on them.

Stephen Hawing in his "A Brief History of Time" proposes that the arrow of time is an artifact of the way our minds process information. Presumably at the atomic level time isn't linear, and atoms are maybe not subject to it at all.

  • I think Barbour too argues for a timeless universe; whereas I think Smolin is for it; Hawkings statement sounds kinda Kantian; but not sure if he would accept that label - given his dissin' of philosophy. – Mozibur Ullah Feb 19 '16 at 8:23

Of course, the answer turns on interpreting "subject to time", one could say that if something is not subject to time it is is not properly speaking "in" time. But I think a more fruitful way to construe the question is to ask if something not in time can interact with things in time. We have to qualify this immediately because not being subject to time at least means that it can not be acted upon from time, so interaction can only go one way, can something not in time act on things in time? To this question both Plato and Christian theology give a positive answer, ideal forms populating Platonic realm are "imitated" by sensible things, moreover we contemplate them in anamnesis, God creates the sensible world from outside of time, and intervenes in it.

But closer to home we find examples in Aristotle's own theory of universals. Unlike Plato's Aristotle's forms do not populate a separate realm, they are embodied, they exist "in" or "beside" the sensible things as their invariances, they "give form" to matter through entelechy, and are directly perceived by us. So they are much more "in time" than Plato's. But on the other hand, not only are they not subject to time, they also have another peculiarity, they can be many places at once while remaining single, they are in space but not subject to space either. The form of circle is one and same as perceived in every imperfect sensible circle. It is through entelechy of form into matter that Aristotle overcame both the erosion of Heraclitean flux and the imperialism of Platonic ideas to affirm a seat for the science of sensible world.

The idea of interpreting the immutability of atoms as immutability of forms was indeed developed, albeit not in antiquity. One can see Leibniz's monadology as idealized form of ancient atomism. Of course, monads are more than just forms or atoms, they are active, they have "living force", but they were seen as vitalized ideal atoms constituting the world in a more subtle non-mechanistic way.


I would say that things that cannot be changed do not necessarily have time. And this is not an antique or purely philosophical notion. Lucretius's notion of the unchanging atoms remains with us in elementary particle theories.

Elementary particles in our current physics seem to lie outside of time. Richard Feynman has noted that the invariant nature of the electron means that we cannot know there are actually multiple electrons, rather than a single one that has travelled back and forth in time, moving backward most of the time when it is far away from us and forward when it is near us.

These particles have quantum numbers to which we assign continuous movements, but we have come to accept that those movements are not coordinated in ordinary time the way that we imagined them for modelling purposes. The 'angular momentum' of a particle in its 720-degree 'rotations' is not a continuous temporal event that we can observe. Particles 'in phase' with one another are 'more real' to one another and more directly interfere. But is that an aspect of them, or of their incomplete presence to our observation? Really, this model for the varying degree to which particles can interfere with one another is more likely to be an aspect of the nature of their immersion in our space, than any actual motion that would be observed in the frame of reference of the particle itself.

According to special relativity, photons, notoriously, have to have a frozen time frame, since they travel at the speed of light. But to the degree the Schroedinger equation is realistic, any particle can theoretically transit out of existence and move to another location in ways that violate relativity. Things that can violate the limit of the speed of light do not seem likely to be able to experience a time shared with us in any way. If they did, information 'available to them' in their own 'timeline' could be borne various places in ways that violate relativity. Instead, we must see not just photons, but all other things small enough to be captured by a single wave equation, as things that do not experience time, or that do so only in ways that cannot be shared with us.

  • There's also Hegel history of philosophy, where he also implicitly states this 'not neccesarily in time'. – Mozibur Ullah Feb 23 '16 at 18:23
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    And Augustine's notion that God and angels are 'eternal', as reflected in Kant's decision that time is a human projection, so that traditional Roman Catholic 'Intelligences' are intelligences. The point was, that it is still with us, even if we reject most of history and just look at current science. – user9166 Feb 23 '16 at 18:44
  • For sure; what are the traditional Roman Catholic 'intelligences' - angels? Or is it an allusion to neo-platonism or Plotinus? – Mozibur Ullah Feb 23 '16 at 19:36
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    Once they are dead, they are officially angels. So that would be kind of wrong? :) I don't mean this man plato.stanford.edu/entries/pseudo-dionysius-areopagite was an angel, I mean this is a kind of angel described in his writings. He is famous for an analysis of the vision of Elijah, reinforced by NeoPlatonic and a little Aristotelian philosophy that describes what kind of angels should exist, and why. It had substantial influence on Scholastic philosophy. – user9166 Feb 23 '16 at 22:22
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    One kind of amusing aspect is that no one knows whether this man is a Saint or not. St. Denis was canonized, and this man is famous for writing a book pretending to be St. Denis. But no one knew the author was a different person at the time of the canonization. So it is really a matter of Scholastic philosophical positions whether or not this man was meant to be included in the rituals that affirmed St. Denis was a saint. If he is a saint, is he St. Denis the Areopagite? If not, he has no name, because that name is taken by the person he was pretending to be. – user9166 Feb 23 '16 at 22:42

We could say, they are in time; but whilst in time, they do not change; they have constancy; this I think, is the usual explanation.

But consider, would we get the same theory, if we supposed these atoms were not subject to time?

As far as I have learned from the origins of the concept of time, motion makes time.

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So if there were only a few stationary atoms in empty space there would be no time, and the atoms would not be "subject to time". On the other hand, if the atoms were moving they would create time and be subject to time.

Also, if there were a few stationary atoms but something else was moving, time would exist and the stationary atoms would again be subject to time.

Note further to down-vote

The link to motion can be observed in that at high speed all mechanisms are slowed down due to their constituent sub-atomic particles being inhibited by the light-speed limit. So time is not universal, (although the moment is). At the speed of light time stops, i.e. there is no time. All this is incidental to my post, which about time in a more fundamental, definitive sense.

That is to say, while a mechanism moving at the speed of light (if it could) would be totally pressed against the light-speed limit and would be frozen "in time", i.e. no motion, elsewhere in the universe someone could be observing so the mechanism would be in time. However in the hypothecated heat-death of the universe there would be only radiation and therefore no time.

Returning to the OP's question:

would we get the same theory, if we supposed these atoms were not subject to time?

If the atoms were stationary in an empty universe there would be no motion, no time, and the atoms would not be subject to time. However if there is discernable relative motion there is time and they are "subject to time", (taking this expression on face value).

This demonstrates that the OP's question is incoherent, misunderstanding time. Despite the Lucretian atoms not changing, if something is moving they are in time.

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