# E = MC2 Explained

Submitted by: buddy 11 years ago in
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http://www.pbs.org/wgbh/nova/einstein/experts.html

Now do you get it? Me neither.
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There are 49 comments:
Female 43
I had a physics teacher that actually did experiments that are now books that are in the library of Congress.....so I already knew a lot of this and could keep up...and yes, I kept an "A" in physics.
Male 45
Jimbo - The "Twin Paradox" is what I think you`re referring to, but that`s unrelated to time travel. If you have two twins and one flies around at relativistic speeds for a while he will indeed be younger than the one that stays at earth. The "Twin Paradox" name turns out to be a misnomer, as it is not actually a paradox, and has actually been confirmed in scientific experiment (they flew atomic clocks around in airplanes, I believe).
Male 170
medic1971: you`re right. That`s the idea behind the time travellers paradox. I`m not sure if you would be able to see yourself take off, but if you had a friend the same age as you, you took off, did a lap of the moon and came back, you`d be younger than your friend when you got back.

Technically speaking, if you were to live at the top of a mountain, you`d also grow older slower than your friend at the bottom of the mountain. By a tiny tiny tiny amount. :D

Male 49
Medic1971: I have pondered the same idea. Theoretically, if travel at speeds above the speed of light were possible you could travel a distance - turn around and view history. However, by returning at speeds faster than light you would not be able to arrive before the light emitting event occurred. In your example you would spend 10 minutes travelling away from the event at 10 X the speed of light and 5 minutes returning at 20 X the speed of light. So by the time you made it back to the event, 15 minutes would have elapsed. With the speed of light at 299,792,458 meters/sec, the light emitted from the event would have already travelled 269,813,212,200 meters from the event that emitted the light.
Male 215
hey everyone, read Neil deGrasse Tyson`s thing and listen to how he says "all" omg it`s so funny.
Male 45
Fusion bombs are difficult to create because fusion only occurs at intense heat and pressures. The center of the sun, for example, is hot and dense enough to force hydrogen into nuclear fusion. Fusion bombs actually require that a fission bomb be built around the hydrogren fuel to explode with enough heat and energy to cause the hydrogen to fuse.

Back to fission bombs: the other hard part about making a fission bomb is creating or isolating enough of the particular isotopes of uranium and plutonium required. Most naturally occuring uranium is the wrong isotope, and plutonium is the wrong isotope and very rare anyways.

I am aware I misspelled "nuclei." I suxx0r.

Male 45
tim1977: Fission bombs are difficult to create because nuclear fission only occurs in a sustained chain reaction if the mass of fissile material is big enough. Nucleii that undergo fission require that they be bombarded with neutrons, at which point they may split into smaller nucleii and a bunch of neutrons, which may or may not cause other nearby nucleii to also undergo fission. Too small a mass of, say, plutonium, and not enough neutrons get created to cause enough other plutonium to undergo fission to sustain the reaction. The main problems in creating a fission bomb are 1) bringing two or more small (subcritical) masses together to form a big enough (supercritical) mass fast enough so that it can release most of its energy in its most compact shape, and 2) keeping the critical mass together long enough so that as much energy as possible is released. (if a little energy is released and the plutonium breaks into two smaller pieces immediately, the reaction will stop).
Female 809
huh?
Male 200
Here is something that is bothering me.... Let`s just say you could get into a rocket ship and take off from earth and travel at say 10 times the speed of light. Then after about 10 minutes you could stop, look back, and watch yourself take off.
Now here is the part that troubles me. What if you took off in a rocket and traveled at 10 times the speed of light, then turned around and came back to earth at 20 times the speed of light. Would you not get back before you left?
Maybe that`s why the speed of light is a the universal speed limit....
Male 694
to tim1977
.
All matter,lets say plutonium,
contains energy.
E=MC2 shows how much.
E=MC2 Energy=the speed of light squared (multaplyed by its self).
in an atomic bomb this energy is relised in the form of movment,heat,light and radiation.
.
.
.
happy now?
Male 49
To the people who actually understand the concept of E=MC2. Why is it so difficult to apply in terms of creating an atomic bomb? What holds a brilliant mind from being able to apply this.
Male 851
but what if you did manage to move at light speed?
you wouldn`t be able to see anything would you? no, you wouldn`t
Male 774
i havent looked at this from what i know, its the MAXIMUM measure of energy that can be given out by something, i dont know how you can get that energy, but get something going lightspeed as mentioned above? and SJW is right in order to propel something lightspeed, you must move it with some that can travel lightspeed or faster, that has mass... which cant be done, sorry
Male 1,882
Very interesting.

My question is, if one were to travel at the true speed of light, and time were to supposedly stop, then it should be impossible for actual light to reach the speed of light. I mean, if time stopped, you could move an infinite amount of distance in zero time, thus achieving an infinite speed. In fact, moving ANY distance whatsoever while time is stopped would equal infinite speed (divide one mile by zero time, the only explanation of the result would be that it simply transported there instantly, meaning infinite speed.)

But, light isn`t instantaneous. If it were, we could see stars disappear the second they die, and not thousands of years after their deaths.

I think one of the people said that flashing a light from a train moving 100 MPH wouldn`t increase the speed of the rays of light because the speed of light mutates the variables for speed (distance and time).

My head hurts... lol... Physics is a very interesting topic.

Male 45
IWillRm(m)brYou: if you think "isn`t" is the correct spelling of "is not," you are an idiot.

I`m sorry; I meant: "...you`re an idiot."

Male 851
heheh
everyone`s trying to smart
it is a simple concept though
so here`s a hard one:
time does not exist, it is merely an illusion created by our minds because of their inability to perceive all instances of being at once
Female 57
And you don`t know how to spell isn`t...
Male 45
"Alot" is not a word.
Male 126
Alot of dumb people in the forums.
Female 1,403
My heaaaaaaaad....owwwwwww. I`m too dumb :-(
And Tedweird, before you call anyone a dumbass spell "you`re" right. And Buddy isn`t a dumbass, if it weren`t for him, I would have no i-am-bored.com and then I would die.
Male 571
I knew all this from when I studied physics in secondary school (high school for you Americans), it made me see things in a different light and after I left the army I started wearing pseudo-intellect glasses even though it was completely un-necessary. It made me look smart... Well the moral of this story is that if you were pseudo-intellect glasses during a tae kwon do sparring you will probably end up in hospital. Truly tragic...
Male 371
i get it but i got it before this so...doesnt really matter(haha thats a crappy pun)
Male 298
it made sense before. Buddy, ur a dumbass.
Male 45
Whatup09: You have no idea what you`re talking about. At all.
Male 1,061
ok then...
Male 694
so what if we`re nerds?
IM A NERD AND PROUD OF IT!!!
btw sjw nice explination.
i couldnt have said it beter myself
Male 733
lol - haha! NERDS!
that makes sense i suppose...
Male 517
gaaah! i`ve already had 2 science lessons today.......
Female 314
Ya`ll scare the crap out of me.
Female 207
im not even going to listen to it. it will no doubt make my brain explode.
Male 329
personally i recall the animaniac`s episode where they meet einstein when he is developing the theory of relativity and they begin to spell acme, and then wakko spells it backwards e mc a, but his a looks like a 2, so einstein then has a revelation and thus became the theory of relativity
Male 579
Janet Conrad Experimental Physicist Columbia University

"For me there`s a lot more to the equation than E = mc2."

....yeeeeaaaahhhhh

Male 1,465
"LOL Americans sound dum"

Nice attitude, and eloquently put, Voltaire...

Male 348
LOL Americans sound dum
Female 31
u wot.... im really confused now
Male 99
I learned about about this in Chem. II last year, so I didn`t bother to watch the videos.
Male 22
hah, this is sort of humerous
Male 1,465
"said that if one were to travel at the speed of light, time would come to a stop in that instance"

Of course it’s all theoretical considering that as an object approaches the speed of light, it’s mass expands infinitely meaning that no mater how much thrust is applied, it will never be enough to propel the object to true light speed. I like to think of the speed of light as natures little speed limit. However, it has been shown that time slows down slightly even at sonic and subsonic speeds. But this is all special relativity. E=mc2 is more of an energy conversion formula. It predicts energy the yield of mater. Something that was instrumental in the creation of the A-bomb. Anywho, this was a cool post since I have a hard time explaining the theories to people who aren’t all that into physics.

Male 2,372
Knowing what we know now, the concept isn`t mind bendingly difficult.

However, back when Einstein first published this theory, no one had ever made the connection between matter (this paperweight on my desk) to enery (unleashing this paperweight`s energy will kick major ass).

He was the first.

Male 820
man they are some cool cats
Male 979
lmao Obeast
Male 65
Bah, begone with your Jewish physics.
Male 169
its not too hard. energy equals any mass times the speed of light scared. einstein said that if one were to travel at the speed of light, time would come to a stop in that instance. at the same time, any mass could be transferred into energy. think about the atomic bomb. the uranium inside the bomb is converted into a great amount of energy using the same formula. btw, im posting this before i even look at that site. im gonna take a gander now.
Male 979
i agree akajune, he rocks! Im confused still. so energy is matter? or what? huh?
Male 149
Michio Kaku is king
Male 209
i already knew all of that
Male 992
OOOOOOOOOOOOOOOOOOOOOOOOOHHHHHHH!!!!! uh what??!!!
Male 158
It actualy makes sense now :-O
Male 10,115
Link: E = MC2 Explained [Rate Link] - Now do you get it? Me neither.