E=mc^2

[caravelair]

A joule isn't mass times the speed of light in a vacuum squared.

Mass times the speed of light in a vacuum squared
is 8.98755179 * 10^16 joules.

well that depends what mass you are talking about, now doesn't it?

 

[Mocca]

well that depends what mass you are talking about, now doesn't it?

Oops, wasn't thinking. Thanks for that correction.

 

[Kripost]

The formula's simple... the problem is people keep saying the unit's wrong, so I substitute it with a new unit... the formula's still simple... the problem is why?

Is E=mc^2 just a formula for finding jouls?

I can understand how it sounds like I'm questioning the wrong thing because I don't accept the fundamental the formula is based upon. Any highschool book will tell you the theory completely and utterly relys on SR... light has to be a constant, and any time we see light moving at a different speed (any time we observe the red/blue shift of a star moving relative to us) that's not really light moving at a different speed relative to us, that's time slowing down, thus changing the frequency of light.

That is what I reject. Reject the flawed fundamental of special relativity and you inherently reject all theories relying on it.

Yes, matter can be converted to energy and vice versa... but why bring the speed of light into it? The speed of light is only a constant in a given medium... as is any wave. Common known fact that light travels faster in the vacuum of space than in our dense, heated atmosphere... but our observations are obviously flawed since time is dilating to suit einstein's needs, when there is no evidence that time dilates at all, nore is there evidence that time is something that can be dilated.

I was trying to get at the flaw of putting the speed of light in the Energy formula because the speed of light isn't a constant... only a constant in a given medium relative to it's source.

To measure a joul as mass times (c^2) is not magic... it doesn't rely on light being a constant... it's simply mass times a number... any number can replace it and the only thing different will be the 'size' of the unit of measurement.

A joule is a unit of energy, equivalent to the work done when a force of one newton acts through a distance of one meter. As in
W = F x d
1 J = (1 N) x 1 m
1 J = (1 kgms^-2) x 1 m

 

[eri]

And while you're reading all the links these helpful people have provided you with, you may want to google 'Are you a quack?' Since I can't post links yet.

And if you're the guy who keeps send the handwritten theories on 'sideways gravity' and why Einstein was wrong to my dept, cut it out. We just keep pitching them.

 

[I_Love_Cheese]

And while you're reading all the links these helpful people have provided you with, you may want to google 'Are you a quack?' Since I can't post links yet.

And if you're the guy who keeps send the handwritten theories on 'sideways gravity' and why Einstein was wrong to my dept, cut it out. We just keep pitching them.

I like it espesially # 18:
" The fact is, the accepted theories already work, so why replace them? To start with, you have to reproduce all the correct results of the established theories: That means you first have to learn those theories, then check that your new theory can successfully reproduce their correct results."

http://insti.physics.sunysb.edu/~siegel/quack.html

 

[eri]

Thanks for posting the link. That's a fun page; very useful.

 

[Telephone]

What if Einstein wasn't from America...

You mean somewhere like Germany ?

 

[Physics_guy]

Yes, matter can be converted to energy and vice versa... but why bring the speed of light into it? The speed of light is only a constant in a given medium... as is any wave. Common known fact that light travels faster in the vacuum of space than in our dense, heated atmosphere... but our observations are obviously flawed since time is dilating to suit einstein's needs, when there is no evidence that time dilates at all, nore is there evidence that time is something that can be dilated.

Little hint there big guy: c=the speed of light in a vacuum, it doesn't equal the speed of light in Earth's atmosphere.

Einstein would be the first to tell you that the speed of light can and does change with its medium, but the propagation of light waves through space do not change, no matter what speed the observer or emitter is moving through space relative to some other point.

Oh, and by the way, time dilation (a totally different but mathematically related concept BTW) has been observed - the GPS system in a car wouldn't work right if GR (of which SR is simply a the special case of the non-accelerating reference frame) were not fundamentally correct (there can always be refinements).

Oh and your units are all messed up in the first post of this thread as numerous others have pointed out.

 

[Physics_guy]

What if einstein weren't from america... would he assume E=MC^2 still? Even though in metric light is about 300,000 KM/second... therefore E=M x 90,000,000,000... now E=M times 90 billion?

By the way - like pretty much all physicists (well except some bozos at NASA), American physicists use the metric system. This was especially true of GERMAN physicists working at the time in Switzerland.

Now besides the history lesson, your point is simply stupid. Whether you use the metric system, the Imperial system, or the Klingon system (I assume there is one - if some geeks make up a whole language, do you think they forgot to translate units of measure?), the units of meausre are irrelevant to the accuracy of the formula. E=mc^2 would be correct in any system of units, as long as you are consistant.

Now as to your question of why Einstein didn't say E=mass times a constant, well, he basically did, but showing the relationship to the speed of light gives you a hint at the derivation of the formula from Maxwell's equations.

By the way - I love your comments about how you know so much about physics yet you couldn't even keep track of units in the first post and later confused force and energy. Yeah - you're likely to be making a trip to Sweden sometime soon for toppling Relativity...

 

[Physics_guy]

but you can't assume that a pound of helium has exactly the same energy as a pound of einsteintinium (for the sake of irony and the fact that I know it's one of them new fangled ones with a really high atomic mass.)

Not that all your other nonsense wasn't entertaining, but why would you think a pound of each would have different energy? Do you think that just because Einsteinium has more baryons in its nucleas that it would have more energy? Now if you said one helium atom versus one Einsteinium atom, this point might make sense, but a pound of each would have pretty much exactly the same number of massive elementary particles.

 

[I_Love_Cheese]

Not that all your other nonsense wasn't entertaining, but why would you think a pound of each would have different energy? Do you think that just because Einsteinium has more baryons in its nucleas that it would have more energy? Now if you said one helium atom versus one Einsteinium atom, this point might make sense, but a pound of each would have pretty much exactly the same number of massive elementary particles.

I was going to ask Gregorian which weighed more, a pound of feathers or a pound of bricks but I didn't want to hear the answer.

 

[Lucretius]

Relativity has been confusing the heck out of me lately but I think I've resolved things; it's that evil Twin Paradox.

Correct me if I'm wrong but the reason one twin ages slower than the other is that, although they both would see accelerated aging on the travelling twins' return trip, and slower aging on their way out, the times at which this switch occurs is different for each observer.

If the traveller is called Bob, then he would see the redshift turn to blueshift the moment he turned, yet the stationary guy, Bill, would only see this change to blueshift after the light from Bob's turning got to him, which would probably be near the end of the journey —not enough time to make up for all the redshift.

Voila one twin is younger… right?

well, that and the fact that the travelling twin is not always in an inertial reference frame…

 

[Osiris]

Relativity has been confusing the heck out of me lately but I think I've resolved things; it's that evil Twin Paradox.

Correct me if I'm wrong but the reason one twin ages slower than the other is that, although they both would see accelerated aging on the travelling twins' return trip, and slower aging on their way out, the times at which this switch occurs is different for each observer.

If the traveller is called Bob, then he would see the redshift turn to blueshift the moment he turned, yet the stationary guy, Bill, would only see this change to blueshift after the light from Bob's turning got to him, which would probably be near the end of the journey —not enough time to make up for all the redshift.

Voila one twin is younger… right?

well, that and the fact that the travelling twin is not always in an inertial reference frame…

My 2¢ is that the reason one twin would be younger than the other has to do with the relevance of time from the perspectie of each brother.

The brother travelling at the speed of light, time would be travelling much slower than the other brother who is not travelling at the speed of light.

The brother travelling at the speed of light, would traverse a long distance within one minute... to the traveller's perspective it may seem longer than one minute (i think).

The brother not travelling at the speed of light, time would fly by at a regular rate of aging. So, if a year goes by... the brother not travelling at the speed of light would be 1 year old, the brother travelling at the speed of light would not be 1 year old but less because time travelled much slower for him.

I think that is how it is... but I could be wrong.

 

[Lucretius]

My 2¢ is that the reason one twin would be younger than the other has to do with the relevance of time from the perspectie of each brother.

The brother travelling at the speed of light, time would be travelling much slower than the other brother who is not travelling at the speed of light.

The brother travelling at the speed of light, would traverse a long distance within one minute... to the traveller's perspective it may seem longer than one minute (i think).

The brother not travelling at the speed of light, time would fly by at a regular rate of aging. So, if a year goes by... the brother not travelling at the speed of light would be 1 year old, the brother travelling at the speed of light would not be 1 year old but less because time travelled much slower for him.

I think that is how it is... but I could be wrong.

That doesn't quite answer it because it doesn't take into account the fact that, to the brother travelling at the speed of light, his own clock would appear to tick at a normal rate. The brother on Earth sees the clock of his twin ticking slower yes, but if the situation were perfectly symmetrical, then the change to blueshift from redshift would be observed at the same time for both brothers, and the equation would balance out.

Yet, the shift doesn't occur at the same time. Since the speed of light is finite, the time it takes for Bill to find out Bob turned around, say, 8 light years away, is another 8 light years. By the time Bill finds out, Bob is about .5 light years away from Earth. Blueshift can't catch up to redshift, voila older twin.

Though you do bring up a good point about the Lorentz contraction that I forget to mention. The distance observed by the travelling twin to his destination is going to be measurably less than what the stationary twin measures…the total distance for the moving observer is less than that for the stationary observer, so two different times are arrived at here too. Again though, it seems to be that timing of the shift of electromagnetic frequency that accounts for the Twin Paradox.

 

[Osiris]

Yet, the shift doesn't occur at the same time. Since the speed of light is finite, the time it takes for Bill to find out Bob turned around, say, 8 light years away, is another 8 light years. By the time Bill finds out, Bob is about .5 light years away from Earth. Blueshift can't catch up to redshift, voila older twin.

Hmmm... how about this... let's forget about the background environment(Earth, Space, ect...). Let's just focus on the two brothers and the light travelling in a vacuum. Also, let's keep track of the median point between the two.

Now, wouldn't the two brothers be moving away from each other at the same speed(in respects to that median point or in respects to each brother's point of view)? And light beeing seen by the Traveller would be the same by how the Non-Traveller might see it (in respects to the light emitted by each brother)? The only difference between the two would be that the traveller experienced time go slower and the Non-traveller experience that same time go faster?

 

[Osiris]

I realized something wrong in my previous post.

I should have said that the same perspective would be the same only in regards to speed between the two.

When they are moving away, the Traveller/Brother is frozen along with the light because they(the traveller and the light) are both travelling at a constant speed while the Non-Traveller is moving away from them (experiencing change).

So, the traveller would not be able to see the Non-travelling brother because light would not reach his eyes (he is travelling at a constant speed with light that light behind him would not reach him). But when he turns around he'd be able to see everything in front of him now (which before was his back) but the difference would still be that the Traveller would still seem frozen along with the surrounding light/particles around him - there will also be light particles that will be travelling opposite to the traveller which would be colliding in his eyes making him see everything in front of him (assuming that his brain is moving at the speed of light as well so that he is able to perceive everything - not just his body).

Also, the Non-travelling brother will be emmitting light, the Travelling brother would not.

So once the brother's start to move away, both brothers would not be able to see each other, the traveller would seem frozen along with the light the non traveller would not. On the way back, the traveller would not emmit light towards his brother because he'd be the light (iow, he'd be travelling along with the light)... but the traveller would be able to see stuff in front of him due to light particles travelling opposite of him. Wouldn't the non-travelling brother only be able to see his travelling-brother after he arrives back?

 

[cyberspork]

EDIT: wow ahah looks like that was already covered, still i needed to get my physics rant out of the way.

Now, I forget which unit of mass einstein used... so I'm going to use the pound...

The pound is not a unit of mass, it is a unit of weight, i.e. it is a force (F=ma or in this case F=mg [mass x gravity]
If you want to use the imperial system, use slugs.
Alternatively, use kilograms which is a unit of mass and is the scientific standard.

Are we to drop the "miles per second" thing? to find the amount of energy in one pound we just multiply that one pound times about 34.6billion? So why doesn't Einstein just say "Energy=massx34.6 billion?" Or does the "miles per second" part have to be there?

Because energy is not a measurement of mass, it is a measure of (mass*distance^2)/time^2, or (kg*m^2)/s^2, which in turn is equal to the Newton*meter. in other words, energy is a measure of how force it takes (a Newton, remember F=ma? well a Newton = kg*m/s^2) to move a certain weight for a certain distance. The unit of Joules is a measurement for energy (1 J = 1 N*m)

I mean, that's how you figure out torque... inchpounds... right? So one pound has 34.6 billion poundmileseconds in it. So... who uses 'poundmileseconds' as a unit of energy?

Torque has nothing to do with this. Where did you get torque from??
(it does also use the Newton*meter for a unit, but its the measure of "force cross distance" and is a vector based quantity, energy is not vector based)

What if einstein weren't from america... would he assume E=MC^2 still? Even though in metric light is about 300,000 KM/second... therefore E=M x 90,000,000,000... now E=M times 90 billion?

So one pound has 90 billion poundkilometerseconds in it? I mean... if it's in billions you wouldn't measure it in kilometers... so 90 trillion pountmeterseconds?

Again, what?? It wouldn't matter if you used meters or km. Secondly, numbers are meaningless in science without units, so 90,000,000,000 is meaningless. You also wouldnt use a pound*kilometer since that would be ridiculous, you would use kg*km. Also since 1 mile = 1.609344 km and since 1 kg = 2.205 lbs then...(186282.397 miles/sec * 1.609 km/mile)^2 = 8.98x10^10 or about 90,000,000,000 km/s.

Or what if it's a measure of light years per year instead of miles per second? 1... so E=m x 1 (since 1 squared is one).

Umm, again... no. First using a light year per year is just...strange. The light year is already measured over one year, ther is no point in dividing it by a year again... watch: 1 light year = the distance light travels in one year. Soooo 3x10^8 m/s * 31,556,926(the number of seconds per year)=9.4605*10^15 meters = the distance light travels in a year, so if you divide that by a year again, you are left with the speed of light, which is 3x10^8 m/s. If you square that, you get the same results! :-O

OK... so what's my point other than to publically announce that I don't agree with what junior highschool teachers are professing about physics?

That would be stupid. You obviously don't understand the material enough to make your own judgement on that (more on this in a minute)

My question is why does einstein butt 'light' into everything? Why not just say E=M times a certain number?

Although light is in fact a constant speed in a vaccuum, the speed of light is not necessarilly the same in all possible universes/dimensions/etc. So just saying it as a variable makes more sense, also it is a little bit difficult to write out m*(2.99792458x10^8)^2 every time, there are other variables as well, like epislon_0 and mu_0 (the permeability of free space and the permeativity of freespace, respectively) (interestingly enough if you take the sqrt(1/(epsilon_0*mu_0)) you get the speed of light. Mu_0 and Epsilon_0 are also constants. They are just numbers, but they are so long and such exact numbers that it makes no sense to wrtie them out when doing mathematical proofs.


To finish this off I would like to say the following

Even though I disagree with the general stance on evolution on these forums, and even though I think that view is a slap in the face to science. I still, above all, respect your opinion and your right to have and state that opinion. I will not, nor would I ever say that you cannot have that view(conversely you should not force that view, and only that view upon others). I understand why that is such a sensitive topic, after all it brings God into the equation. But physics is separate. Physics has nothing that would call faith into question, physics doesnt try to answer anything else other than how stuff in the universe operates. Other sciences take physics and then try to answer questions about the world, but physics does not. There is no reason to 'not believe' physics. It is the fundimental basis on our knowledge of the world, if Einstein was so wrong, and if physics were a bunch of hogwash, I can assure you that there would have been no nuclear weapons, but at the same time, you would certainly not be sitting at a home computer writing on the internet! You would probably be living a life somewhat similar to the Amish.


Now for a little about me(saying this will probably get the post deleted, but that would be outright persecution and/or discrimination, so I beg of you not to)
I am Jewish, not a very religious Jew, but I am very proud to be Jewish. To me it means more as a culture as opposed to a religion.

I am also a scientist and an electrical engineer by training. I beleive that God(or religion) has no place in science, and science has no place in religion, they are two separate doctorines, it would be like comparing apples to oranges so to speak. I base my beliefs on what can be backed up by the scientific method.

And lastly, I am a liberal. I know this is a dirty word to many of you on the forums, but I would like to also try to break that stereotype. Liberals are not all devil-worshiping evil homosexuals hellbent on destroying your children (I'm using hyperbole) but in fact, most liberals are just like you or me. We just have different views on society and economics, but if you are proud to be an American, you should not be questioning the Americanism of liberals or calling them Un-American either, that is ... well, un-American. The Bill of Rights, and in particular the freedom of speech grants us unprecidented rights and something that most countries do not have, we should cherish this and not try to destroy it.

On a final note, as was already mentioned, Einstein was indeed Jewish. He was also very religious, and believed viamently in God, as for whether he took the old testament word for word, that I do not know; however he did once say an interesting thing, and that is what I will leave you with tonight: "God does not play dice."

 

[sfs]

Your confusion about units has been addressed by several people, although I don't know if you've understood the replies. Other comments . . .

Imporper math, but it happens.... He didn't believe gravity existed, so why should he believe in proper math? He always admitted to being horrible at math.

When did he admit to being horrible at math? He needed help with the Riemannian geometry needed for General Relativity, but the simple algebra involved in Special Relativity was trivial for someone like Einstein.

[...]

Anywho... if E=MC^2 is right... if all other energy is negligable,

All other energy is not neglible. Where did you get that idea? E=mc^2 tells you how much energy is contained in a given amount of rest mass -- that's all. It doesn't tell how what other energy there might be present in the system, or whether it's more or less than the rest mass.

and the energy latent in the foundation of matter is all that must be calculated to convert a unit of mass to a unit of energy... here's my question?

if E=MC^2... then one photon has the same energy as any other particle of the same mass. I mean... the kinetic energy in a photon going the speed of light is negligable, right?

No, wrong. The kinetic energy of a photon can be enormous. (And all photons go at the speed of light.)

If the kinetic energy in a photon is not negligable than kinetic energy, heat energy, potential energy, etc. can not be nglected either.

What I'd like to see.... is someone lay out the math for me... go step by step and show me how much energy, in jouls there is in one kilogram... maybe I can use your math as a reference.

That would be more than a little complicated. You would need a description of the kinetic energy of the constitutents, and the binding energy holding things together, and the energy of vibrational and rotational states. Why would you want this, and what does it have to do with special relativity (much less evolution)?

Special Relativity is accepted, like every other good scientific theory, because it works. When massive objects travel at speeds close to the speed of light, they behave as if time were moving slower for them; this can be seen very easily in subatomic particles, which decay slower and slower (orders of magnitude slower) as they move faster. As particles approach the speed of light, they become more and more difficult to accelerate, and no matter how much energy you pump into them, they never go faster than c. When a massive particle decays into massless particles, the energy released is exactly that predicted by the formula you're attacking.

And so on. Thousands of experiments done over decades are explained to very high precision by Special Relativity. Physicists aren't going to stop using SR until they have a very good reason to do so. What you've offered isn't a good reason, or even a bad reason, it's just confusion.

 

[corvus_corax]

The pound is not a unit of mass, it is a unit of weight, i.e. it is a force (F=ma or in this case F=mg [mass x gravity]
If you want to use the imperial system, use slugs.
Alternatively, use kilograms which is a unit of mass and is the scientific standard.

Just to clarify (and using layman's terms)
Mass is a quantifying of the amount of matter and energy an object has.
Weight is...well, weight.
For instance, my weight here on earth is 190 pounds.
On the moon, my weight would be much less
However, my mass (the amount of matter and energy contained in my body) would remain the same.
For Americans, mass (typically measured in Kilos) and weight (typically measured in pounds) are easily conflated, since Kilo mass can (just light Pound weight) be measured on a scale.
But the two are not the same.
Weight varies based on attraction
Mass stays the same (no matter where you are in the universe)

 

[Kornelius]

For Americans, mass (typically measured in Kilos)...

Mass is measured in grams in the metric system. Kilo is just a prefix meaning 1000. So one kilogram is 1000 grams. Kinda like a kilobyte (although that is 1024 bytes)