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# Misconceptions of E=MC^2

Author Topic:   Misconceptions of E=MC^2
cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 38 of 243 (452098) 01-29-2008 2:02 PM Reply to: Message 27 by pelican01-29-2008 1:43 PM

Re: what is the rush
 Oh I think I do percieve the speed of light squared. I just cannot percieve any mass travelling at that speed, can you?

:rolleyes: E=mc^2 has nothing to do with a mass travelling at the speed of light. Here, c is just a number, and c^2 forms the constant of proportionality between E and m. This number is also the speed of light, but that is (mostly) irrelevant to the equation.

It is tested true every second of every day at every nuclear reactor in the world. None of the billion \$ particle accelerators in the world would work at all if this equation was not true.

There are very few equations in science that are better tested than this one...

 This message is a reply to: Message 27 by pelican, posted 01-29-2008 1:43 PM pelican has responded

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cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 40 of 243 (452102) 01-29-2008 2:05 PM Reply to: Message 35 by pelican01-29-2008 1:59 PM

 E=MC2 means a piece of matter travels at he speed of light squared and changes form to become energy.

No, it most certainly does not.

Glad to clear up the misconception.

 This message is a reply to: Message 35 by pelican, posted 01-29-2008 1:59 PM pelican has responded

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cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 46 of 243 (452113) 01-29-2008 2:36 PM Reply to: Message 44 by New Cat's Eye01-29-2008 2:26 PM

Re: E=MC2 experiments
 Hrm. I thought that, theoretically, if (the big IF) mass did travel at that speed, then it would be light. I.e. it would become light.

Absoluetly not. Pseudo-scientific bullshit perpetuated in popular science and all over the internet...

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cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 80 of 243 (452346) 01-30-2008 4:31 AM Reply to: Message 69 by pelican01-30-2008 12:21 AM

Re: E=MC2 experiments
 the theory of producing matter from energy using the speed of light squared has never been proved, only the reverse.

:laugh: You know absolutely NOTHING about this subject, so why are you so intent on making a complete idiot of yourself?

Take a look at this picture:

 Click to enlarge

{Source here}

THAT is the creation of matter (electron/positron pair) from energy, perfectly obeying e=mc^2. This happens billions of times a day at the particle accelerators around the world.

 This I believe is a common misconception amongst the members in this forum.

:laugh: :laugh: :laugh:

Why have we suddenly a forum full of arrogant idiots? You haven't a clue about this subject so why are you so sure that the problem lies with others and not with yourself?

 This message is a reply to: Message 69 by pelican, posted 01-30-2008 12:21 AM pelican has responded

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cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 82 of 243 (452352) 01-30-2008 5:26 AM Reply to: Message 48 by humoshi01-29-2008 2:54 PM

 Chiroptera writes:What the equation means is that when energy is converted to matter with mass, then the amount of mass is equal to the amount of energy times the square of the speed of light.

Does is really make sense to say energy is converted to mass or vice versa? This would seem to violate the conservation of energy.

Is it more accurate to say that one form of energy called mass is converted to another form of energy

No, mass is not a form of energy - mass is a measure of energy, irrespective of the form of the energy. The space-time curvature generated by a pair of photons is exactly the same after they have pair-created an eletcron and a positron. The energy will now be in the form of the rest-mass of the particles plus the interaction energy between them.

The measured mass of 1kg of lead consists of almost entirely the binding energy (i.e. gluons) holding the quarks, and in turn, the nucleons together, plus the binding energy (i.e. photons) holding the electrons, and in turn, the atoms together, plus the vibrational energy (i.e. photons) of the temperature of the lead, and finally plus a vanishingly small amount of energy from the rest-mass of the quarks and eletrons making up the actual matter.

If you put that lead into a container with 1kg of anti-lead, and managed perfect annihilation all the way down to just having photons left, AND managed to contain those photons within the container, then you would still have 2kg inside the container...

Edited by cavediver, : No reason given.

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cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 84 of 243 (452354) 01-30-2008 5:42 AM Reply to: Message 81 by pelican01-30-2008 5:03 AM

Re: E=MC2 experiments
 My apologies for looking like an idiot and thankyou mobigirl.

The wisest words you have uttered all this thread. There is hope for you. Now apply that humility when you read my post above.

 This message is a reply to: Message 81 by pelican, posted 01-30-2008 5:03 AM pelican has responded

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cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 87 of 243 (452363) 01-30-2008 7:11 AM Reply to: Message 86 by pelican01-30-2008 7:00 AM

Re: E=MC2 experiments
 What do you want from me?

To quieten down and listen to what you are being told. For you to realise that you are very mistaken about all of this. Nearly everyone repsonding to you is reasonably well grounded in this subject. In my case, it was my profession for ten years.

 I see what you mean, hey cavediver?

I'm not the one claiming insight in a field in which I have no experience...

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cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 91 of 243 (452368) 01-30-2008 7:37 AM Reply to: Message 88 by pelican01-30-2008 7:15 AM

Re: energy and mass
 However to obtain a small amount of mass from a huge amount of energy cannot be proved and cannot be tested. I contend that some believe e=mc2 has been verifed by testing and this is not true, only in reverse. It is asserted to be true because it must be.

So, just for the record Heinrik, you are contending that every particle factory in the world doesn't actually work, and every particle physicist in the world is lying, and hiding a huge conspiracy that we have never observed pair creation :laugh:

You are utterly deluded, and beyond help. Truly pathetic. I just hope that the hundreds of lurkers who have perused this thread have managed to see beyond your mad frothy ranting and raving and have actually perhaps learned something about particle physics.

Bye bye

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cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 92 of 243 (452369) 01-30-2008 7:39 AM Reply to: Message 89 by pelican01-30-2008 7:22 AM

Re: don't insult me
 You don't even rcognise your own arrogance

Arrogance is misplaced confidence. I can assure you that my confidence is very well placed :D

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cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 133 of 243 (453033) 02-01-2008 9:14 AM Reply to: Message 130 by Minnemooseus02-01-2008 4:36 AM

Re: 0.6 grams of mass lost at Hiroshima
What you have to remember is that there is nothing special about nuclear reactions creating 'mass loss'. Chemical reactions do exactly the same. If we say Little Boy was 15kilotons, then a conventional explosion of 15,000 tons of TNT will also create a mass loss of around 0.6g.

In both nuclear explosions and chemical explosuions, the energy released comes from the binding energy - binding energy of the nucleus and binding energy of the atoms/molecules. This binding energy has an assocaited mass via E=mc^2, and it is the loss of this energy that gives rise to the 'mass loss'. No actual matter was harmed in the course of either explosion :)

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cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
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 Message 137 of 243 (453051) 02-01-2008 10:14 AM Reply to: Message 135 by Rahvin02-01-2008 9:21 AM

Re: 0.6 grams of mass lost at Hiroshima
 In both nuclear explosions and chemical explosuions, the energy released comes from the binding energy - binding energy of the nucleus and binding energy of the atoms/molecules.

This is different from antimatter/matter annihilation, however, where the particles are actually fully transformed into high-energy photons. Is that correct?

Yes, that is 'real' matter to non-matter. The rest mass of the electron and positron is released as energy which dictates the frequency of the two emitted photons.

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cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 141 of 243 (453059) 02-01-2008 10:42 AM Reply to: Message 140 by Tanypteryx02-01-2008 10:36 AM

Re: 0.6 grams of mass lost at Hiroshima
 I know the emitted photons will be at 511 KeV, but what is their frequency?

If there's only two photons, and the the electron/positron were low energy (i.e low Kinetic Energy) then the photons will be 511KeV. E = h x v, where h is Plancks Constant and v is frequency (Greek nu actually), so a quick calc and you find that they are Gamma Ray photns with a freq of....

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cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 144 of 243 (453127) 02-01-2008 1:32 PM Reply to: Message 142 by Tanypteryx02-01-2008 12:52 PM

Re: 0.6 grams of mass lost at Hiroshima
 v=7.711838623^35
:eek:

I think you've got your enegy units mixed up :) h is usually in Joule seconds.

1 eV = 1.6Ã—10^âˆ’19 J.

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cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 164 of 243 (453470) 02-02-2008 9:52 AM Reply to: Message 160 by Percy02-02-2008 9:04 AM

Re: mass * the speed of light squared = energy ?
E = mc2 / (1-v2/c2)1/2

E = mc2 (1-v2/c2)-1/2

small v, so taylor expand

(1-v2/c2)-1/2 = (1 -(-1/2)v2/c2+...)

so

E = mc2(1 + 1/2v2/c2+...)

E = mc2 + 1/2mv2 + ...

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cavediver
Member (Idle past 2063 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 166 of 243 (453484) 02-02-2008 10:46 AM Reply to: Message 165 by Percy02-02-2008 10:26 AM

Re: mass * the speed of light squared = energy ?
Despite the appearance of that Wiki article, it's actually standard senior high school advanced calculus - though in these days of diminishing standards in the UK, it's out of single A-Level mathematics and only remains in one-and-a-half or double maths. I expect you did study it at one point...

This wiki entry is better and provides the proof using basic integral calculus (work through it - it's not as bad as it looks)

Essentially you are approximating a curve at a point by using a straight line with the same gradient at that point, plus a parabola with the same quadratic curvature at that point, plus a cubic, etc

Edited by cavediver, : No reason given.

Edited by cavediver, : No reason given.

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