# Thread: Argument supporting existence of a God

1. Originally Posted by Clete
E=mc^2 is not an aproximation of anything, least of all the speed of light.
Sorry, I misspoke. The formula is an approximation. Not of lightspeed.

Having said that, we are clearly more in agreement than not. My entire point about the speed of light is that it isn't merely a mathematical construct and that it definitely does travel, neither of which you really disagree with - I don't think.
Right.

I'm not sure where this conversation took a turn, but it seemed to me the disagreement was mostly over semantics.

2. Originally Posted by Stripe
Sorry, I misspoke. The formula is an approximation. Not of lightspeed.
What do you mean an approximation? The formula is not that Energy is "nearly equal" to mass times the speed of light squared. Equations are a type of sentence and the phrase "is equal to" is denoted by the "=". It's not an approximation at all.

It's a notion that has been tested over and over and over again. It explains so many observed phenomena that it's just shocking. Everything from atomic bombs to the missing mass of decayed radioactive materials and a hundred things in-between. I can't imagine what you could mean by an approximation.

Right.

I'm not sure where this conversation took a turn, but it seemed to me the disagreement was mostly over semantics.
Probably so, at least between you and I, any way.

Clete

3. You brainiacs are fun to read. Sure wish I could join you.

4. Originally Posted by Clete
What do you mean an approximation?
It was derived using the first term of a Taylor series.

It's a notion that has been tested over and over and over again. It explains so many observed phenomena that it's just shocking. Everything from atomic bombs to the missing mass of decayed radioactive materials and a hundred things in-between. I can't imagine what you could mean by an approximation.
There's no reason an approximation cannot be useful.

Einstein's ideas are useful. But I think there are better ideas out there.

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6. Originally Posted by Stripe
It was derived using the first term of a Taylor series.

There's no reason an approximation cannot be useful.

Einstein's ideas are useful. But I think there are better ideas out there.
Sorry, but that just frankly dumb.

It's not an aproximation by any definition of the word. It's only the most famous equation the world has ever known. It has been repeated tested and retested, varified and reverified, over and over and over and over both by direct experimental measurement under laboratory conditions as well as indirectly as consiquence of other related experimental and oberservation data.

I have no idea what would motivate you to call it an aproximatiob but it has nothing to do with sciennce or the facts of reality.

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8. Originally Posted by Clete
What do you mean an approximation? The formula is not that Energy is "nearly equal" to mass times the speed of light squared. Equations are a type of sentence and the phrase "is equal to" is denoted by the "=". It's not an approximation at all.

It's a notion that has been tested over and over and over again. It explains so many observed phenomena that it's just shocking. Everything from atomic bombs to the missing mass of decayed radioactive materials and a hundred things in-between. I can't imagine what you could mean by an approximation.
Perhaps Stripe's thinking about that the 'm' in E=mc^2 is "relativistic" mass, and not just mass as we know it? idk, I just wondered.

Question for you though Clete: Light travels slower when it passes through a medium of some sort, something less than c. If light were to pass through a medium, and then emerge from that medium, does light then regain its maximum velocity of c, or does it maintain its slower velocity that it had when traveling through the medium? The medium could be for instance water, or glass.

I ask because I've heard that light has some non-zero value for mass. idk if this is true, but if it is non-zero, then it has a momentum, and if it is traveling slower, then its momentum is lower, and if it resumed maximum velocity of c, then it would somehow have to acquire momentum, so I'm just checking my understanding here with you, if you don't mind.

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10. Is this true for every value of E and m?
c = √(E/m)

If it is not, then c is a mathematical constant useful for calculating E from m or m from E and is not a physical constraint.

It only works in these two versions:
E = mc2
m = E/c2

11. Originally Posted by Idolater
Perhaps Stripe's thinking about that the 'm' in E=mc^2 is "relativistic" mass, and not just mass as we know it? idk, I just wondered.

Question for you though Clete: Light travels slower when it passes through a medium of some sort, something less than c. If light were to pass through a medium, and then emerge from that medium, does light then regain its maximum velocity of c, or does it maintain its slower velocity that it had when traveling through the medium? The medium could be for instance water, or glass.

I ask because I've heard that light has some non-zero value for mass. idk if this is true, but if it is non-zero, then it has a momentum, and if it is traveling slower, then its momentum is lower, and if it resumed maximum velocity of c, then it would somehow have to acquire momentum, so I'm just checking my understanding here with you, if you don't mind.
Light has no mass. That is why it travels at the speed of light. All massless particles and only massless particles travel at c.

Light always travels at the fastest possible speed through whatever medium it is traveling through. If it's traveling through water or glass or air or hydrogen or a vacuum or whatever else you can think of. Whatever is the fastest possible speed for anything to travel through that substance, that's the speed light travels through it at. Incidentally, there is no acceleration or deceleration curve. It instantly changes speed based on the physics of whatever its propagating through.

Terrific question, by the way.

Clete

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13. Originally Posted by Clete
I have no idea what would motivate you to call it an approximation.
Maths.

Again, an approximation can still give useful, highly accurate results.

22/7 is almost always a good enough approximation of pi.

14. Originally Posted by Idolater
Perhaps Stripe's thinking about that the 'm' in E=mc^2 is "relativistic" mass, and not just mass as we know it? idk, I just wondered.
You don't have to guess what I'm thinking; I wrote it in that post up there:

Originally Posted by Stripe
[Einstein's equation] was derived using the first term of a Taylor series.

15. Originally Posted by Stripe
Maths.

Again, an approximation can still give useful, highly accurate results.

22/7 is almost always a good enough approximation of pi.
But it isn't pi and not at all anything remotely similar to E=mc^2

Just as Pi is PRECISELY equal to the circumference of a circle divided by is diameter, mass converted to joules of energy is PRECISELY equal to the mass in kilograms times 89875517873681764.

Further more, units of measure are arbitrary and can be defined as anything you want so long as everyone using them is on the same page. As it stands right right, there is no sense whatsoever in which the speed of light in a vacuum is an approximation. The meter has been officially defined as the distance light travels in a vacuum in 1/299792458th of a second. This means that the speed of light is EXACTLY 299792458 meters per second.

That's not a wish, a guess or a theory nor any other sort of approximate value. It cannot get any more exactly accurate than that - period.

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JudgeRightly (February 21st, 2019)

17. Originally Posted by Stripe
Maths.

Again, an approximation can still give useful, highly accurate results.

22/7 is almost always a good enough approximation of pi.
But it isn't pi and not at all anything remotely similar to E=mc^2

Just as π is PRECISELY equal to the circumference of a circle divided by its diameter, mass converted to joules of energy is PRECISELY equal to the mass in kilograms times 89875517873681764.

Further more, units of measure are arbitrary and can be defined as anything you want so long as everyone using them is on the same page. As it stands right now, there is no sense whatsoever in which the speed of light in a vacuum is an approximation. The meter has been officially defined as the distance light travels in a vacuum in 1/299792458th of a second. This means that the speed of light is EXACTLY 299792458 meters per second.

That's not a wish, a guess or a theory nor any other sort of approximate value. It cannot get any more exactly accurate than that - period.

18. Originally Posted by Clete
Light has no mass. That is why it travels at the speed of light. All massless particles and only massless particles travel at c.

Light always travels at the fastest possible speed through whatever medium it is traveling through. If it's traveling through water or glass or air or hydrogen or a vacuum or whatever else you can think of. Whatever is the fastest possible speed for anything to travel through that substance, that's the speed light travels through it at. Incidentally, there is no acceleration or deceleration curve. It instantly changes speed based on the physics of whatever its propagating through.

Terrific question, by the way.

Clete
Thank you.

As it turns out, light does have momentum, and I think that is part of why I was thinking that there is some obviously minute mass associated with light, but it looks like even without mass, light still can possess momentum. But that returns me to my question, with a little twist on it now. If light has momentum, and passing through a medium reduces its velocity, then I also suppose that therefor its momentum also diminishes, but perhaps that's not necessarily the case, because it appears that the momentum of light is dependent upon its wavelength more than any mass or lack thereof, it appears that momentum for light is derived differently than it is for something with real mass.

I'm just beginning to unravel what was hidden from me in my years of physics courses in school, where teachers for some reason didn't explain very well the relationship between momentum, force, acceleration, and the conservation of momentum. It's proven very powerful for me now in understanding some concepts that I missed, through imo a bit of a deficit in teaching procedure for this subject. At least in my case.

Momentum is mathematically just mass multiplied by velocity (when dealing with things that have mass), which is close to the math of kinetic energy, which is half the mass multiplied by the velocity squared. When a massive (not large, just something with non-zero mass) object changes its velocity, it also, mathematically, changes its momentum, since its mass remains unchanged but it's velocity changes. The only way that an object can change its velocity is through the application of a force upon it, and so in a sense, momentum Is force, even though I know that force is mathematically defined as mass multiplied by acceleration, the bottom line is that a massive object that accelerates acquires momentum, and a massive object that decelerates 'sloughs off' momentum, as force, acting on its environment or upon another massive object.

So I remain confused about how light even though it has no mass, nonetheless has momentum, and I'm trying to work it all through cogently. And understanding the relationship between momentum and force has clarified some things, and has led me to wonder about now others, in this case, light.

So thank you again!

19. Originally Posted by Stripe
You don't have to guess what I'm thinking; I wrote it in that post up there:
OK.

20. Originally Posted by Stripe
... 22/7 is almost always a good enough approximation of pi.
I remember 3.14159 and have for a while now. 22/7 = 3.14286 rounded by comparison, which is a difference of 4 more parts in 10,000, which means that you're probably in almost every case correct; it is "good enough." By another comparison, the most commonly used approximation 3.14 is a difference of 5.1 less parts per 10,000---still quite a small difference and in almost every case, 3.14 is also probably good enough for what people need the number for.

I think that in dealing with circles in a plane, that 3.14 is probably good enough, but when you are calculating spheres, then those additional significant digits come into play more. Compared with 3.14159, the cubes for 22/7 and 3.14 diverge by 12.1 parts more per 10,000, and 15.2 parts less per 10,000, respectively, which might become more of a significant error, when calculating the volume of spheres.

Knowing what I do about the number pi, it does irk me a little when people call March 14 "pi day," because my own approximation of 3.14159 is so much more accurate than 3.14, but 3.14159 doesn't lend itself do a date, and I don't suppose there's any harm in people who don't even know what pi is, to think that whatever it is, it's "equal to" 3.14.

I have wondered what in nature is the perfectest circle. Because the endless string of digits that computers crunch when computing pi is based upon a perfect circle, which until I see some evidence otherwise, I don't believe exists anywhere in nature or in man made things. A perfect circle is a concept, with no bearing on reality, iow, so far as I can tell.

So what is the value in consuming all the electricity that computers consume when calculating pi? idk. idk of any application where it's necessary to know pi to anything beyond PPM or PPB (parts per billion) accuracy. That's nine significant digits. I think the most accurate approximations of pi are on the order of millions of significant digits, maybe I'm even off there by a factor of millions, or even trillions, but in any case, idk of an application that would require even nine significant digits.

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