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Comment by Lewton | Hacker News Reader

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Lewton·

> this change may be as much as one centimetre per second per year

Anyone have an idea what that's supposed to mean?

Edit: Ah, thanks to both of you, it seems obvious now

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It has the unit-dimension the same of acceleration (that is [Length]/[Time]^2), so it should be read as:

'Every year, the velocity of the distant quasars (going away relative us) is increased by 1 cm/s.'

Could there be a similar observation of this if time were slowing slightly?

I don't see how. Also, what would "time slowing slightly" even mean? That is, what frame of reference is time slowing against? How would we even measure that effect, given that all of our tools which measure time do so my detecting a fixed interval of it passing? Intervals which would also be "slowed".

To be more specific, if our reference time were slowing slightly, where 'our' is defined as all humans and devices making the measurements.

I think our time would have to be slowing different amounts w.r.t. objects at different distances from us. This would imply a Universe-wide effect on the rate of passage of time which is coincidentally centered on Earth, or at least on our group of galaxies. Universal expansion has the advantage that it doesn't require the Earth to happen to be at a special privileged point in the cosmos.

That if something has a velocity of X cm/sec this year, it might have a velocity of (X+1) cm/sec next year.

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