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WaxRubiks
2017-Oct-04, 05:12 AM
I wondered if the size of an atom was proportionate the value of c, and if it was then as you reduced c, all measuring rulers would shrink as well, so c would remain the same.

I just woke up! But I was wondering this the other day.

Jens
2017-Oct-04, 05:20 AM
Well, I think the size of atoms is dependent on the strong force and electromagnetic force mostly, which do not have c as a component, so I don't see why changing the speed of light One issue with that question is that it is so hypothetical. You can't change the speed of light, so if you could, who knows how other things would change?

WaxRubiks
2017-Oct-04, 05:26 AM
Well, I think the size of atoms is dependent on the strong force and electromagnetic force mostly, which do not have c as a component, so I don't see why changing the speed of light One issue with that question is that it is so hypothetical. You can't change the speed of light, so if you could, who knows how other things would change?

yes, but the electromagnetic forces propagate at what ever value of c there is is, don't they?

I was thinking if you had a simulation of the universe on a computer what would happen if you changed the value of c.

WaxRubiks
2017-Oct-04, 05:44 AM
I was thinking, in my head thing, that what ever value of c there is, even if it were 10meters/s, that we wouldn't notice the difference...as all yardsticks would have shrunk...and the measurement of time passing would have changed as well....I was thinking that all physical reality is ordered around the speed of light..and its speed is only measured by the things(like yardsticks) that are determined by c.

People seem to think of the speed of light in the same way they think of the speed of a rocket, like some kind of ordinary thing...which is why some people seem to think that one day we might be able to go faster than c.

John Mendenhall
2017-Oct-04, 01:55 PM
I was thinking, in my head thing, that what ever value of c there is, even if it were 10meters/s, that we wouldn't notice the difference...as all yardsticks would have shrunk...and the measurement of time passing would have changed as well....I was thinking that all physical reality is ordered around the speed of light..and its speed is only measured by the things(like yardsticks) that are determined by c.

People seem to think of the speed of light in the same way they think of the speed of a rocket, like some kind of ordinary thing...which is why some people seem to think that one day we might be able to go faster than c.

I think your speculations about changes in lentgth and time are incorrect, but others can argue them better than me. What about frequency?

grant hutchison
2017-Oct-04, 03:57 PM
Changing c would change the fine structure constant, which sets the strength of the electromagnetic coupling of charged particles. Changing the fine structure constant changes the way, for instance, stars work - the stop producing carbon, or stop fusing altogether. Change it too much and you'll render matter unstable, I think.
But you won't make it smaller.

Grant Hutchison

BigDon
2017-Oct-04, 11:12 PM
To quote Dr. Venkmen,

"Right! Important safety tip, don't cross the streams!"

wd40
2017-Oct-10, 12:58 PM
Changing c would change the fine structure constant, which sets the strength of the electromagnetic coupling of charged particles. Changing the fine structure constant changes the way, for instance, stars work - the stop producing carbon, or stop fusing altogether. Change it too much and you'll render matter unstable, I think.
But you won't make it smaller.

Grant Hutchison

Halving c would seem to be catastrophic. But if it was reduced by just 1%, who and how would be the very first to notice: navigational satellites, ring gyroscopes, astronomers, police radars, the Conférence Générale des Poids et Mesures?

LaurieAG
2017-Oct-11, 10:47 AM
I wondered if the size of an atom was proportionate the value of c, and if it was then as you reduced c, all measuring rulers would shrink as well, so c would remain the same.

I just woke up! But I was wondering this the other day.

In 1964 G. Schlesinger asked "Is it false that Overnight everything has doubled in size" so you could probably just google the quote.

WaxRubiks
2017-Oct-11, 09:05 PM
In 1964 G. Schlesinger asked "Is it false that Overnight everything has doubled in size" so you could probably just google the quote.

yes, I have wondered that as well....it seems to me that changing c would be similar, and that no body would notice it..

grant hutchison
2017-Oct-11, 09:09 PM
yes, I have wondered that as well....it seems to me that changing c would be similar, and that no body would notice it..But it wouldn't be similar, and we would notice it.

Grant Hutchison

grant hutchison
2017-Oct-11, 09:14 PM
In 1964 G. Schlesinger asked "Is it false that Overnight everything has doubled in size" so you could probably just google the quote.Of course, Schlesinger answer to that question was "Yes it is false, because we would have noticed."

Grant Hutchison

Ken G
2017-Oct-11, 11:38 PM
Physics uses a bunch of unitless numbers, that are formed by combinations of parameters like c. But you cannot go the other direction, because no combination of unitless numbers can result in a number with units. Ironically, this means any quantity that has units is not an absolutely real quantity, it is always a comparison with something that does not have an absolute size of its own. But the unitless numbers do have an absolutely real quality, they cannot be changed into a different value without changing something you can notice. So it's not like doubling all distances-- distances have units, so are not actually numbers, they are comparisons of numbers to reference values that themselves do not have an absolute size. Put differently, there is no such thing as an absolute distance, or an absolute anything else that has units-- there is not even an absolute value for the speed of light (which is why its value is often taken to be 1). But the unitless numbers do matter, they are "real" in a sense that is not true for quantities that have units. (5 meters is only a meaningful length if you know what a meter is, but there is no absolute meaning of a meter, it is a comparison too. But the fine structure constant is a ratio like the ratio of the radius of the Earth to the radius of the Sun, and ratios like that have the same meaning in all units systems, whereas the value for the speed of light depends on the units.)

Here's a good way to think about this. Take any formula that has a constant in it, and repackage it to look like a formula that has no constant, but compares two situations. This is the way I feel we should write all our formulas, but it's not typical. For example, we have the rest energy of the electron is E = m c2, where c is regarded as a constant. Repackage that as the rest energy of the electron, relative to the Planck energy, given as a function of the rest mass of the electron, relative to the Planck mass. Now it looks like
E/Ep = m/mp
so the constant is gone. When we write all our formulas like that, we never need a speed of light, as all speeds are automatically measured relative to the speed of light anyway-- and that relative ratio is all that has physical significance. Hence we see the "speed of light" has no physical significance other than its ratio to other speeds we are interested in. Changing c must then mean changing that ratio, or nothing is changing.

rbar
2017-Oct-12, 02:46 AM
Choose your favourite inertial reference frame. All observable events have a time t associated with them.

Define a new time variable t^{\star}=2 t.

Make all observations, measurements, express all physical laws, etc., in terms of t^{\star} instead of t.

The speed of light is now half of what it was before.

LaurieAG
2017-Oct-12, 05:53 AM
But the fine structure constant is a ratio like the ratio of the radius of the Earth to the radius of the Sun, and ratios like that have the same meaning in all units systems, whereas the value for the speed of light depends on the units.

Good thinking Ken G.

The Planck 2013/15 data viewed through the prism of LambdaCDM gives us total universal matter comprised of 25.8% dark matter and 4.82% visible/ordinary matter. The universal ratio of total matter to visible/ordinary matter is 30.62/4.82 or 2 * Pi +/- 1.1% to 1.

Sometimes I wonder if the whole dm thingy is being pushed by a small cliche of obsessive retro dark lord ID'ists because surely any number of mature adults would have fessed up by now that they'd made an error, especially when it's so bleeding obvious and all lines of research have led nowhere.

Ken G
2017-Oct-12, 07:10 AM
It is true that the ratio of dark matter to ordinary matter is one of nature's unitless numbers, and any change in it is something we would notice. It might be pure coincidence that it comes out close to 2pi, akin to the coincidences of numerology, or there might be some deep reason there for all we know, but it is certainly not an error-- I'm afraid that's ridiculous.

swampyankee
2017-Oct-12, 09:48 AM
Choose your favourite inertial reference frame. All observable events have a time t associated with them.

Define a new time variable t^{\star}=2 t.

Make all observations, measurements, express all physical laws, etc., in terms of t^{\star} instead of t.

The speed of light is now half of what it was before.

Good luck rewriting Maxwell's equations so the behavior of all the capacitors and inductors remains consistent. Every test of special relativity is, indirectly, a test of Maxwell's equations, as that's where the concept of the invariance of light speed first appeared.

rbar
2017-Oct-12, 12:23 PM
Good luck rewriting Maxwell's equations so the behavior of all the capacitors and inductors remains consistent.

Not much luck is required. In fact, not much rewriting is required. Just write then down exactly as they are now.

Read my earlier post again, and think about it for a while. You'll get it eventually.

Ken G
2017-Oct-12, 02:10 PM
The point is, there is a crucial difference between the concept of "the speed of light" and the quantity "the speed of light." The way we teach quantities with units tends to obscure this profound difference. If we started calling two seconds what used to be called one second, that would indeed halve the quantity of the speed of light, but not the meaning of the concept, so would have no impact on anything that happens around us. This is because the meanings of all concepts that have units are not quantities, the meanings are ratios or comparisons. The speed of light has meaning only insofar as we can ratio it to other speeds we feel we already understand. Changing what we call a second will not change the meaning of those ratios. It's a shame we teach quantities with units as though they were numbers, when in fact all they ever were are comparisons. Numbers never have units.

So this is the answer. Doubling the speed of light may, or may not, have any impact on anything we observe. If all we do is double the quantity of the speed, but keep all the speed ratios the same, it has no effect. If we change the ratio to other speeds, then it does have an effect, and atoms fall apart and so on.

rbar
2017-Oct-12, 02:54 PM
If we started calling two seconds what used to be called one second

Exactly my proposal.

so would have no impact on anything that happens around us.

No impact on anything at all. I have already responded to my critic who seems to feel I need to rewrite Maxwell's equations, but my earlier post has not yet received the Good Housekeeping Seal of Approval.

I'm of the opinion that the speed of light is half the usual speed on Tuesdays and the third Friday of every month, in my time zone, and the usual speed at all other times. The exception is February 29th, when, notwithstanding the previous rules, the speed of light is always five times the usual amount, until 21:30, when it reverts to normal speed.

Not even falsifiable.

Ken G
2017-Oct-12, 03:39 PM
Exactly my proposal.
I know, that's why I mentioned it. I was explaining why changing how we count time doesn't matter to physical outcomes, but changing the speed of light would-- if it means changing the ratio of the speed of light to speeds in situations we already understand in some way.

No impact on anything at all. I have already responded to my critic who seems to feel I need to rewrite Maxwell's equations, but my earlier post has not yet received the Good Housekeeping Seal of Approval.My clarification was based on the potential ambiguity in your response. It wasn't clear if you felt that changing the unit of time sufficed to "double the speed of light," because the original question was also ambiguous on what that meant. My point is there are two completely different interpretations of "doubling the speed of light," one being to double its quantitative value but not its ratios to other speeds (your approach), and the other is to indeed double those ratios (grant hutchison's original answer). So it's not that I don't approve of your answer, it is that you only answered one potential interpretation of the question.

I'm of the opinion that the speed of light is half the usual speed on Tuesdays and the third Friday of every month, in my time zone, and the usual speed at all other times. Again, what you are saying here is ambiguous, because you have not stated if you are keeping the ratios the same on those days! The problem is that our language falls too easily into this ambiguity, because we have not stressed the crucial difference between a speed as a quantity, versus a speed as a ratio.

ETA: I can expound. Many people think a speed is a ratio of a distance to a time, because we teach it that way. But that is incorrect, that's just not what a speed actually is, because it falls under the pretense that distances and times are things in and of themself that you could ratio. What is actually true is that ratioing a distance to a time is no more meaningful than trying to equate a distance to a time. What does have meaning is to ratio like quantities, like a distance to a distance and a time to a time. Thus, what a speed actually means is a ratio of distance to a reference distance, divided by a ratio of a time to a reference time. That's a more sophisticated understanding, but that's what a speed actually is, in physics. So if we keep to this meaning of a speed when we say "double the speed of light," we remove the ambiguity, and we get what grant hutchison said-- a very different universe. If we don't keep to that meaning, and imagine that a speed is just the quantitative outcome of a ratio of a distance to a time, then we can imagine that doubling the speed only means doubling the numerical outcome of that ratio, which does nothing if it does not change the actual physical meaning of the speed, which is what you are talking about.

grant hutchison
2017-Oct-12, 10:20 PM
The point is, there is a crucial difference between the concept of "the speed of light" and the quantity "the speed of light." The way we teach quantities with units tends to obscure this profound difference. If we started calling two seconds what used to be called one second, that would indeed halve the quantity of the speed of light, but not the meaning of the concept, so would have no impact on anything that happens around us. This is because the meanings of all concepts that have units are not quantities, the meanings are ratios or comparisons. The speed of light has meaning only insofar as we can ratio it to other speeds we feel we already understand. Changing what we call a second will not change the meaning of those ratios. It's a shame we teach quantities with units as though they were numbers, when in fact all they ever were are comparisons. Numbers never have units.

So this is the answer. Doubling the speed of light may, or may not, have any impact on anything we observe. If all we do is double the quantity of the speed, but keep all the speed ratios the same, it has no effect. If we change the ratio to other speeds, then it does have an effect, and atoms fall apart and so on.And this applies to quantities that have units of speed, even though it may not be evident that they do.

For instance if we choose time units that halve the numerical value of c, we also halve the numerical value of e2/(ε0h) (because the change in time units will double the numerical value of Planck's constant, h). Under dimensional analysis, e2/(ε0h) turns out to have units of speed, and the ratio of c and e2/(ε0h) determines the dimensionless fine structure constant, which therefore remains unchanged by our simple fiddling with the units.

Grant Hutchison

swampyankee
2017-Oct-13, 01:05 AM
Not much luck is required. In fact, not much rewriting is required. Just write then down exactly as they are now.

Read my earlier post again, and think about it for a while. You'll get it eventually.

Are you just playing with units? I was thinking that you wouldn't do something like measure time in one frame and distance in another to measure velocity. Is that what you're doing? If so, that's cheating.

Ken G
2017-Oct-13, 02:32 AM
I would argue that we should always express all our fop]rmulas in unitless form, and then we'd never have this confusion. For example, we no longer say F = GMm/d2 for the "force of gravity," as if that force were some kind of absolute "thing." Instead, we say the force of gravity in situation 1 relative to situation 2 obeys
F1/F2 = (M1/M2) (m1/m2) / (d1/d2)2 .
Yes it takes longer to write it this way, but the conceptual advantages are significant, and one actually begins to understand what the "gravitational constant G" actually means. In particular, one never needs to choose an arbitrary unit system, as it should be obvious that nature cares not a whit about that. Also notice that all ratios are either comparisons of "like things", or they are simple arithmetic operations on pure numbers-- in short, they are what ratios and division actually are, not like the confused way division is used with quantities that have units.

swampyankee
2017-Oct-13, 10:23 PM
I would argue that we should always express all our fop]rmulas in unitless form, and then we'd never have this confusion. For example, we no longer say F = GMm/d2 for the "force of gravity," as if that force were some kind of absolute "thing." Instead, we say the force of gravity in situation 1 relative to situation 2 obeys
F1/F2 = (M1/M2) (m1/m2) / (d1/d2)2 .
Yes it takes longer to write it this way, but the conceptual advantages are significant, and one actually begins to understand what the "gravitational constant G" actually means. In particular, one never needs to choose an arbitrary unit system, as it should be obvious that nature cares not a whit about that. Also notice that all ratios are either comparisons of "like things", or they are simple arithmetic operations on pure numbers-- in short, they are what ratios and division actually are, not like the confused way division is used with quantities that have units.

When it's important, we have dimensionless quantities: Mach, Reynolds, Strouhal, etc.

Ken G
2017-Oct-14, 04:15 AM
When it's important, we have dimensionless quantities: Mach, Reynolds, Strouhal, etc.
Yes, I like to imagine the dimensionless quantities are the "only numbers nature knows."

LaurieAG
2017-Oct-15, 02:42 AM
It is true that the ratio of dark matter to ordinary matter is one of nature's unitless numbers, and any change in it is something we would notice. It might be pure coincidence that it comes out close to 2pi, akin to the coincidences of numerology, or there might be some deep reason there for all we know, but it is certainly not an error-- I'm afraid that's ridiculous.

You should really bother to read the posts you comment on Ken G as errors happen all the time and the ratio is between all matter and ordinary matter.

Ken G
2017-Oct-15, 04:10 AM
No, errors like that do not "happen all the time," that claim is simply ridiculous. Are you really equating a trivial oversight in a forum post to an error by an entire community? Seriously, this is going to be your argument here?

swampyankee
2017-Oct-15, 11:06 PM
Yes, I like to imagine the dimensionless quantities are the "only numbers nature knows."

....and one finds them with dimensional analysis. They’re tough to measure.

WaxRubiks
2017-Oct-16, 12:02 AM
I wondered the other week, whether the only actual things that matter are angles...I guess an angle can be expressed as a ratio with a complete circle.

grant hutchison
2017-Oct-16, 12:07 AM
I guess an angle can be expressed as a ratio with a complete circle.Is expressed.

Grant Hutchison

Ken G
2017-Oct-16, 12:32 AM
....and one finds them with dimensional analysis. They’re tough to measure.Exactly, so it also means that nature doesn't "get" our measurements-- that's on us. So there are really three types of quantities, the dimensionless numbers that in some sense define the nature of the phenomena that nature supports, the invariants, which have units so include the actions or thoughts of some kind of scientist, and the coordinate-dependent quantities we measure, which not only depend on the scientists, they depend on the scientists' personal perspective. One might regard that list in order of descending degree that nature herself "knows about" these quantities.

LaurieAG
2017-Oct-16, 07:58 AM
No, errors like that do not "happen all the time," that claim is simply ridiculous. Are you really equating a trivial oversight in a forum post to an error by an entire community? Seriously, this is going to be your argument here?

You made the exact same mistake before Ken G, deliberately so.

Ken G
2017-Oct-16, 01:53 PM
So you are admitting that the logic of your argument here involves equating a trivial and unimportant mistake in a forum post with a hugely significant repeated error made by an entire community. That's what I thought. The only question anyone here has is, why don't you see the weakness of that argument?

LaurieAG
2017-Oct-19, 07:58 AM
I was referring to your tactic of building up a straw man to avoid questioning why 2 * Pi should pop up out of the universal blue, as the ratio between all matter as calculated and all visible matter as observed. Third time lucky Ken G.

grant hutchison
2017-Oct-19, 11:47 AM
Curiously, the dimensionless ratio between the speed of light and the product of Earth's polar gravity and draconic (eclipse) year is equal to one (+/- 2%). So we have the origin of the number line derived from the relationship between a universal constant and the fundamental nature of the Earth/moon/sun system. Seems like a put-up job to me.

Grant Hutchison

Ken G
2017-Oct-19, 01:57 PM
Clearly we should redefine the second to make that number unity!

publiusr
2017-Oct-31, 08:02 PM
At close to lightspeed, you become compressed.

Near a black hole--you get stretched.

So if you enter a black hole at almost lightspeed--then what?

Reality Check
2017-Oct-31, 08:34 PM
At close to light speed, other people measure that you become compressed. You measure and experience no compression.
Near any mass, you get stretched and this goes to extremes inside the event horizon of black holes.
So if you enter a black hole at almost light speed, you get spaghettified (https://en.wikipedia.org/wiki/Spaghettification).