Truely universal time and distance

[Dooby]

What would be a truly universal measure of time and distance be?

Obviously, seconds, hours and years, light years wouldn't mean the same on another planet. And miles and kilometers are also arbitrary and wouldn't mean anything to another civilisation.

I was thinking something along the lines of time being measured by rotations of an electron around a hydrogen atom. And then distance being measured in light in a given time from the electron.

I know both of these can be affected by magnetism/gravity, but its the most basic thing I can think of.

What do you guys think?

 

[3dilettante]

Setting down a base unit of time is pretty arbitrary.
The second has been retroactively defined in terms of a physical phenomena (courtesy wiki)

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

Another time constant, or at least a very common one would be something based on Planck time.
This is the time taken by light in a vacuum to travel a distance of 1 Planck length.
The use of the speed of light in a vacuum means that component is constant, going by relativity.
The Planck length is the smallest any distance can effectively be.

Granted, if any of several universal constants were to be found to be less than constant, it is no longer quite as universal.

 

[Davros]

I'm not sure about that, the plank I have is about 6 feet long

 

[3dilettante]

It's obviously not special enough, since its first letter is lower case and it's spelled properly. It takes a very special one to warrant capitalization and its own spelling.

 

[Dooby]

Thats a bit too obscure for what Im trying to think off. Thats such an arbitrary number that you would never have based a time system off it. 1million or 10 billion passes of something maybe, but 9,192,631,770 is just a "what goes into a second". I want something more concrete.

 

[3dilettante]

Thats a bit too obscure for what Im trying to think off. Thats such an arbitrary number that you would never have based a time system off it. 1million or 10 billion passes of something maybe, but 9,192,631,770 is just a "what goes into a second". I want something more concrete.

It was retroactively defined, as in "what in nature can we use to match what we already call a second", and the ground state transition was what was picked. It's arbitrary. They weren't going to blow up centuries of timekeeping to find a neater unit of time.

Outside of something based on what we believe to be constants, like Planck time, a base unit of time is going to be whatever we want to use.

 

[hoho]

Well, both time and distance have been defined pretty nicely already. Sure, time has rather arbitrary number attatched to the definition but there aren't really many other events going on that would be constant enough to be used as etalon. Once time is defined it's easy to define metre from it using light speed as helper. Defining metre through other means is just asking for problems.

 

[_xxx_]

None, since both time and distance are relative, see Einstein or modern quantum mechanics.

Using atoms for measuring is bonkers. Say Hydrogen, which one of the 6 isotopes would you prefer? Which electron energy level? In what environment? And on and on - there is simply no valid reference since nothing is predictable or constant, nor completely isolated from any interactions.

Aside from that, time is really just an illusion produced by our senses. In effect distance is also just that, our ape-brain limitation in spacetime.

What we have now is just a clutch, but anything else instead would be also that, just in another package.

 

[Davros]

We thought we had a fixed unit for time called XXXTime,
but it changed from a couple of weeks to a year

 

[_xxx_]

It never changed, you just missed the initial discussion. Or do you want me to google that post for you? No prob, can do if it's too much for you.

And once more, please keep that bull in RPSC where it belongs. This is the second time in just over a week that you drag RPSC discussions into the open here.

 

[Arwin]

We thought we had a fixed unit for time called XXXTime,
but it changed from a couple of weeks to a year

None, since both time and distance are relative, see Einstein or modern quantum mechanics.

...

In all seriousness though, I agree with _xxx_ on this one (oh, and Einstein). Distance needs something to be distant from, so is relative. Movement is change of that difference, and time is measuring movement against other movement. So the best values are always going to be the best values in a certain context. In the scale of huge distances, the speed of light is a pretty decent yardstick, and the meter has now officially been defined in relation to the speed of light in a vacuum.

I think your confusion comes from the fact that if you talk about lightyears, you've already combined the constant of speed of light in a vacuum with two other things, the earth and the sun.

 

[_xxx_]

The speed of light in vacuum is also not a constant, even there it's still affected by gravity.

 

[Arwin]

The speed of light in vacuum is also not a constant, even there it's still affected by gravity.

But is the path of light affected by gravity, or the speed of light?

Talking about gravity, doesn't gravity also travel at the speed of light? So we could use that as well perhaps?

 

[Dooby]

Well, both time and distance have been defined pretty nicely already.

Defining metre through other means is just asking for problems.

My point is, if we made contact with another species entirely, a second wouldn't mean anything to them. A metre wouldn't mean anything to them. So we would give them directions to our planet and say "its 90 billion miles from the left turn at the black hole" and they wouldn't know what a mile was and end up in the middle of a star somewhere else.

So, what could 2, or 3, or 4 completely seperate civilisations use as a time and distance that each would be able to understand and quantify.

This also makes the assumption they are at least at the level of technology that we are now.

 

[3dilettante]

If the goal is to tell somebody on another planet where we are, NASA uses a map that positions the solar system relative to pulsars, and it has placed it on various probes that have exited our neighborhood.
The Voyager golden records use hydrogen electron orbital transition time to give a base unit of time, which is used to then indicate the period of those pulsars for identification purposes. Given its ubiquity in space and its simple dynamics, that element is about the best we can do.

If the assumption is that the aliens have picked up a signal, it's really on them to figure out how to look back in its general direction and figure things out.

 

[_xxx_]

But is the path of light affected by gravity, or the speed of light?

Talking about gravity, doesn't gravity also travel at the speed of light? So we could use that as well perhaps?

I tend to think it's both.

Gravity - well I'd like to, but so far our science has no idea what gravity is or how it works Really, not a slightest idea, despite thousands of theories which all can't yet be proven.

It's a futile exercise, so far we really have no firm reference for anything at all. We only have relative measures based on our limited and relative world view.

Also, time is useless anyway - the subjective time is always different. You feel time differently when you're in a highly extatic active state or when you're apathic and sitting in the darkness, or say when you're high or when you have sex or when you're being tortured by the inquisition for what I care. Sometimes seconds are like hours or vice versa.

Also if we eventually should have space travellers, their time and our time would diverge very soon, so even with a "firm" reference, it would be futile - because that firm reference would be only valid for a static situation on any place. Think about that.

There is an interesting book i read recently from a guy called Cathie. Think Erich von Daeniken but from New Zealand, mysteries, aliens, free energy etc. He developed his own version of unified field theory and what seems a very plausible maths theory along with that. Some stunning and crazy stuff in there, it would explain many things if there's any merit to it. Among other things the relations of gravity, speed of light in different media, electromagnetic fields etc.
But this or that way, it's a very interesting and entertaining read that fits this topic quite well, so I can recommend it.

 

[rpg.314]

Gravity - well I'd like to, but so far our science has no idea what gravity is or how it works Really, not a slightest idea, despite thousands of theories which all can't yet be proven.

You never take a break, do you?

 

[3dilettante]

Light can be influenced by gravity, but the constant c is not affected by gravity.
When deriving certain units, we would be using c, not whatever speed light happens to have in the room at the moment.

Assuming these are advanced enough aliens to have at least the idea of nuclear power/weapons, the value of c will most likely be as clear to them as it is to us.

Barring some variation in the constants, which has not yet been found, our best bet is to assume their constants are the same as ours.

 

[Frank]

Google "universal constants". The first hit (wikipedia, physical constant) is pretty good.

In general, these are constants defined by the nature of the universe, not something arbitrary as the more-or-less random division of the rotation of some planet by 86400.

The Planck ones are probably the best candidates, as far as we know. Because they don't depend upon any other units than those universal constants.

 

[_xxx_]

You never take a break, do you?

Why, it's just the simple truth. Gravity is so far still a mystery.