[Bullet Magnet]

The problem here is that you are addressing a philosophical viewpoint, and I the scientific. Specifically, yours seems to be that time neither flows not has a present through which the universe flows, but is an intellectual structure that we use to compare events and order them sequentially. This for me is exceedingly unsatisfactory, since it is an anthropomorphisation (something that I always oppose) that implies that without humans to observe the universe, time does not exist. This further implies that therefore time is not necessary for change, since change has clearly occured without a present observer. This leads to the requirement to have a way to distinguish time from change, and holds that time itself cannot be measured, this last point to me is like fingers on a chalk board.

Ultimately it is a philosophical angle, and I haven't had a very high opinion of philosophy since a friend of mine answered a philosophical exam question with an otherwise irrelevant philosophical argument to the effect that the question does not really exist and that his answer is therefore not an answer and should not contribute any marks. He got an A.

In science, as I have said, time is a fundamental quantity. It is used to define many physical concepts that we know to be real (speed, acceleration etc) so must be real itself. However, being a fundamental quantity, it cannot be defined by another fundamental quantity, since this would lead to a circular definition to the effect of "time is time" or "time exists because time exists" which is unacceptable and most unsatisfactory.

Science has and needs only an operational definition of time. Like temperature, which is defined in terms of operations with a gas thermometer, a most accurate and sophisticated instrument by which we can standardise it, and thus derive figures from the world around us for use in calculations. Is temperature, then, subjective, anthropocentric and ultimately undefinable? Likewise, the operational definition of time, specifically the SI-unit of time, the second, which is itself defined, officially, as:

The duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the Caesium-133 atom.

This definition refers to a caesium atom at rest at a temperature of 0 K.

The ground state is a stationary state in quantum mechanics, and therefore a state of definite energy whose corresponding probability density has no time dependence. It is also set at mean sea level, or the gravitational time dilation effect would change the length of the second with altitude.

This is our means of measuring the passage of time, yes, but for 9,192,631,770 periods to occur there as to be a regular transition of crest to trough in a sinusoidal waveform, which of course there it. Here we stray into trigonometry, which, along with waves and transitional periods of radiation, exist whether or not there are intelligent beings using them to quantitatively define the passage of time in order to usefully measure their experience of change and time, which inevitably occur.

In order for there to be crests and troughs in a wave, there has to be at least two distinct states for the universe to exist in: one in which the emitter of the wave is emitting at peak amplitude and another in which the emitter is emitting at nadir amplitude. And then the universe must move from one state to the other, with any intermediate states in between that form a (functionally) continuous bridge. This change of state is time, it is permitted because time exists. If time did not exist, there would be no way for the universe to change from one state to another, thus, it would be locked in one state. I would use "eternally" to describe this, but that is meaningless without there being time.

Alien intelligence probably does not use Caesium-133 to define their scientific unit of time. This does not mean that it is impossible to convert one to the other as we would feet to meters. Their experience of time may be significantly different to ours, and their unit(s) may reflect this, but such would be down to their metabolic speed, which would affect their nervous/equivalent rate, but not the nature of time. Indeed, intelligence cannot exist without time because (and this is but one of many reasons) intelligence requires information to move from one place to another, which cannot occur where the universe cannot proceed from one state to the next.