The first bit is the most practical, then it gets difficult.

Use the Planck time as the basic unit of time, the Planck length as the unit of length, the velocity of light in vacuo as the unit of velocity, the mass of the electron as the unit of mass and the charge of the electron as the unit of electrical
charge. Define other units from these terms. Rather than using the usual decimal multiple units, use the binary multiple system kibi-, mebi- and so forth. No subunits are needed, because nothing physical can be said to exist at a smaller scale than the basic units.

Two more, less practical, proposals. Base the calendar on these units. This is not in itself difficult, but finding a date to count from is unless an event in the early Universe can be pinpointed. Clearly the Big Bang is the most important such event, but it can't be precisely dated. Therefore, provisionally, choose the Julian date until a better one comes along. This would unfortunately mean there would be negative dates.

Clearly days would be a peculiar number of units in length, as would years, but these are parochial considerations based on an insignificant little blue-green planet orbiting an unregarded yellow sun rather than anything that really matters.

The other proposal, even less practical, is to get the whole population of the planet to abandon their current counting systems in favour of binary. Rather than using cumbersome long strings of ones and zeroes, however, they are to say the sounds /i/ for one and /o/ for zero separated by glottal stops, and there would be no ambiguity.

If the universe is expanding, is the Planck length a constant, and if so, am I going to have to revise my Planck length every Planck time to compensate?

If you have a unit of time and of distance then one unit of distance can only be travelled in one unit of time by one unit of matter that must fit exactly in one unit of distance. This is illogical and does not describe reality.

So time and space are not divisible in units and I will go one step further and say that matter is also not divisible in units. Yep the universe is one blur.

So rather then putting everything in order by these or any other scientific rules and units I propose we divide our living space in stretches of how long they feel, in units of tiredness from walking for example.

And time also, possibly in units of boredom.

What with everybody having different perceptions and feelings we would need much more communication to understand eachother. Or at least we could have a good laugh about how strange everything is.

And even if it does matter, does it matter that it matters?

[zeno], you made me smile and i also note the parallel between what you say and your paradoxes of motion.

I think you are talking about measuring Gegend or the spatiality of Dasein, whereas i am talking about Cartesian space-time, which is less real in a way. I suppose you could, and probably people do, divide their lives up into how long they see themselves as having, which is maybe why time goes faster as one gets older. I like the blobby world too, but i also like the crystal world.

Thanks. However, how are we to know the whole of physics, which tells us these things, isn't just provisional and useful? Aliens might have a completely different set of theories and concepts that works just as well, so these units might be just as provincial as miles, days and pounds.

If all derived measures are dimensionless. I will be even more likely to mix kW and kWh [as they are now known], and if they become just dimensionless numbers who would know?

If you're going to reset the calendar, just start coutning down to a point arbitrarily far in the future. It provides lots of entertainiment when you get close to that point and people have forgotten why it was chosen.

I'm wrong again, so I’ll take back the bone I gave.
Apparently to possible to arbitrary add beck on “unit markers” to stop thing descending into a see of dimensionless numbers.

This brings up the possibility of making useful every day units out of planck units.

1*10[7] is about 218g, a convenient mass for every day use. So call 1*10[7] planck masses a “roc” or something else that gives an impression of mass, and a unit marker to help keep the maths strait. For industry 1*10[12] (21760kg very roughly) a “lode”

1*10[34] (vaguely 4 inches) planck lengths could be called a “rool”. And so on for all of the basic and derived units. The exact comparison with SI units is not in the least important, what is important is people will have a set of units for normal use. but when the kids start learning science or engineering, once they learn a few conversions and how to multiply by 10, they are of to a flying start.

I'm still looking for SI units for analogies, so you can mathematically predict when they been pushed too far. Might also work on Church of England sermons?

Here's my problem with Plank Units and the non-continuous hypothesis that allowing integers to represent real-world values provides.

Say an atom moves* 1 Plank Unit North, and then 1 Plank Unit East. How far is it from its original location? Can you get `/2 Plank Units? No, because they're indivisible, involate, integer inventions.

*Of course it can't actually move, it has to instantaneously transport itself and all of its constituent fundamental particles this distance in less than or equal to 1 Plank Unit of Time.

RE: `/ - anyone got a better way to represent the square-root symbol?

//Say an atom moves* 1 Plank Unit North, and then 1 Plank Unit East. How far is it from its original location? Can you get `/2 Plank Units? No, because they're indivisible, involate, integer inventions.//

I think it's best to 'unask' that question, sensu Hofstadter, because it is based on incorrect assumptions.

Here's an attempt at an analogy. Take ocean waves. Below a certain length, ordinary ocean waves don't exist, because surface tension and viscosity forces become very large in comparison to kinetic and gravitational forces. I will guess this length to be 3 mm.

In this context, your question is like asking:

Say a storm system moves* 3 mm North, and then 3 mm East. How far is it from its original location? Can you get `/2*3 mm? No, because 3 mm are indivisible, involate, integer inventions.

*Of course it can't actually move, it has to instantaneously transport itself and all of its constituent waves this distance in less than or equal to 3 mm divided by the speed of ocean waves of Time.

It's a meaningless question, and a meaningless answer, for much the same reasons as the original.

[pocmloc], [lurch] it can't work that way, otherwise things moving diagonally to the universe would go twice as fast!

[spidermother] I take your point, but I don't think the problem is quite as fundamental as that - it's just a case of size. So instead of a thunderstorm/atom, what about instead we watch some fundamental, tiny thing, like a photon?

It's not just a question of size; yes, I picked a storm system to reflect that compared to the Plank length even a subatomic particle is colossal, and an atom is colossaller still, but (with respect) virtually every part of the question is flawed.

Many of the same objections occur with a photon, which would equate to a single set of waves like the ripples from a stone.

There is nothing forbidding movement by an irrational multiple of the Plank length, just as there is no rule saying that a wave can move by 3 mm or 6 mm but not by 3*sqrt(2) mm.

In fact, the opposite is the case. An event having some scale (such as a wavelength) of sqrt(2) Plank length is possible, but would require an almost inconceivable concentration of energy, whereas exactly 1 Plank length would involve a breakdown of the laws of physics - a photon with this wavelength would tear space-time and be a black hole!

I think my analogy is a rather good one; and it is as fundamental as that. For instance, an attempt to create waves on water with wavelength less than the lower limit would, instead, shake the water apart into droplets, since the water surface simply can't curve that sharply, which is closely analogous to what a theoretical event below or at the Plank length would do to space-time.