# E=Mc2

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#### Mordred

##### Guest
Ok were all familiar with the equation however I have some questions on this. I once read that any excess energy that drives a proton at the speed of light will convert to matter. This if I'm correct limits the proton at the speed of light.
Is this in fact a correct interpretation if so the one question I've always asked since reading that is, What form of matter does it form?
A more philisophical question I've always had on the observable. If the only way to measure something is through observation would we not claim that that is the absolute speed?
One good example is what we describe as the beginning of the universe with regards to seeing into the past. Light is our only way to see events that far back into the past. As the light has not reached us yet before that point. Is not calling that the beginning merely a mistake due to whats observable?

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#### MeteorWayne

##### Guest
No object with mass can ever reach the speed of light, since it would require an infinite amout of anergy to accelerate it to that speed. Nothing is converted.

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#### Gravity_Ray

##### Guest
Mordred":1p2hcj8m said:
Ok were all familiar with the equation however I have some questions on this. I once read that any excess energy that drives a proton at the speed of light will convert to matter. This if I'm correct limits the proton at the speed of light.
Is this in fact a correct interpretation if so the one question I've always asked since reading that is, What form of matter does it form?
A more philisophical question I've always had on the observable. If the only way to measure something is through observation would we not claim that that is the absolute speed?
One good example is what we describe as the beginning of the universe with regards to seeing into the past. Light is our only way to see events that far back into the past. As the light has not reached us yet before that point. Is not calling that the beginning merely a mistake due to whats observable?

MW answered your first question. But I am curious where you read that “excess energy that drives a proton at the speed of light convert to matter”? I haven’t read something like that before?

The beginning of the universe is still being worked on with bigger and yet bigger telescopes that look further and further in time. One thing to keep in mind, light is ONLY the speed limit IN the universe. The universe itself has in the past expanded faster than the speed of light (during the inflation period). This does not break the rule of the speed limit in the universe as the big bang was not an explosion IN the universe but the explosion OF the universe.

Also even if we do see the big bang that still doesn’t prove that is the "beginning" of the universe. Just what we can observe since anything that happened before the big bang is outside of our realm of reality and so not subject to our rules anyway. The beginning therefore is just an arbitrary starting point for our brains, but God is not subject to our laws.

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#### SpeedFreek

##### Guest
Mordred":2cwb0kui said:
One good example is what we describe as the beginning of the universe with regards to seeing into the past. Light is our only way to see events that far back into the past. As the light has not reached us yet before that point. Is not calling that the beginning merely a mistake due to whats observable?

If light has not reached us yet, it must because our universe had a beginning. Otherwise, why would the light not have reached us yet?

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#### Mordred

##### Guest
Now were getting somewhere. Ther is a whole body of particles that are considered massless Non bayonic I beleive.
or weakly interactive particles. A photon has mass yet the constant speed of light states that the photon can never exceed the speed of light.
Does this hold true for massless particles?
At what point does a massless particle gain mass?
According to the equation above it would have to be when that massless particle gains enough energy to gain mass.

Thats one of the funny quandaries I have with Dark matter and the theory that it is comprised of non baryonic particles. which have no mass yet dark matter comprises 80% of the matter in the universe. The other problem I had is that when a particle whether its a photon or massless reaches the speed of light, time becomes infinite. You often here theories of particles possible moving backward in time. Yet Stephen Hawkings proposed the Hawkings radiation or tachyon as mathematically it can exist. We know that gravity can effect the direction of light through its curvature in space. We know that dark matter is something that does exist as we can see the lensing effects on light.
So how does energy become matter? We know that matter can be converted to energy, why not the other way around?

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#### captdude

##### Guest
Particle colliders create mass from energy on a daily basis.

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#### origin

##### Guest
Mordred":1hwl39ev said:
Now were getting somewhere. Ther is a whole body of particles that are considered massless Non bayonic I beleive.
or weakly interactive particles. A photon has mass yet the constant speed of light states that the photon can never exceed the speed of light. [\quote]

A photon does not have mass. If it had mass it could not travel at c. Nothing can exceed the speed of light!

Does this hold true for massless particles?
At what point does a massless particle gain mass?
According to the equation above it would have to be when that massless particle gains enough energy to gain mass.

This is a very confused paragraph. E=mc^2 simply discribes the equivilancy between mass and energy. Adding energy to a massless particle does not mean it gains mass it only means it gains energy. A photon is a massless particle, there can be huge differences in the amount of energy contained in the photon. A photon of blue light cannot pass through a piece of paper but a gama ray photon can go through 4 inches of steel. Neither photon has mass and both photons are going exactly the same speed (c). The energy is manifested by a shorter wavellength in the higher energy photons.

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#### Kessy

##### Guest
Mordred, you seem to be a little confused about several issues here, you might want to read up a little on Special Relativity. I would suggest Wikipedia's introduction to the subject.
http://en.wikipedia.org/wiki/Introducti ... relativity

I personally think that explaining E = mc^2 as a conversion between mass and energy isn't really the best way to think about it. It's actually an equivalence between the two - in other words, where there is mass there is energy, and where there is energy there is mass. You can think of mass and energy as being two different aspects of the same thing.

It can be a little confusing because it's easy to confuse apparent mass with rest mass. Remember that Special Relativity says that the apparent mass of an object will change depending on how fast that object is traveling relative to the observer - the faster an object is traveling the more apparent mass it will have, according to this formula:

Apparent mass = rest mass / sqrt ( 1 - v^2/c^2)

As the velocity of the object approaches c, the denominator approaches zero, which means the apparent mass approaches infinity. This is why it's impossible to accelerate an object with a rest mass to the speed of light. It gets a little weird when dealing with "massless" particles such as a photon. Since such particles always move at c, the formula becomes Apparent mass = 0/0. 0/0 is undefined, because it can equal any value. This is why your old math teacher told you never to divide by zero, strange things happen. So the end result is that particles like photons must always move at c, and have no rest mass, and yet they *do* have an apparent mass, and therefore also have energy and momentum.

What E = mc^2 is really saying is that any time you do anything to increase the energy of something in any way, you will also increase its apparent mass. So a compressed spring will have ever so slightly more mass then a relaxed spring; a hot object will have ever so slightly more mass then a cold object. When you're talking about a process that "converts" mass to energy, such as a nuclear reaction, what happens is that the apparent mass stays the same, but since the reaction releases a lot of photons, which have apparent but not rest mass, the total rest mass of the products of the reaction are less then the rest mass of the reactants.

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#### ramparts

##### Guest
Also I think the OP claimed that photons have mass? That's not true. They're massless, which is why they can travel at c

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#### Mordred

##### Guest
What E = mc^2 is really saying is that any time you do anything to increase the energy of something in any way, you will also increase its apparent mass

Ok that is probably where I had gotten confused on the question thanks for that info and link

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#### alphachapmtl

##### Guest
E^2 = p^2 c^2 + m^2 c^4 is the correct equation.

At rest, this becomes E = m c^2.

The mass m is constant, it does not change with speed, it is sometimes called the rest mass.

If you accelerate a proton, energy goes into a faster proton, it does not go into matter.

A

#### amshak

##### Guest
Gravity_Ray":5kf6ggrl said:
The beginning of the universe is still being worked on with bigger and yet bigger telescopes that look further and further in time. One thing to keep in mind, light is ONLY the speed limit IN the universe. The universe itself has in the past expanded faster than the speed of light (during the inflation period). This does not break the rule of the speed limit in the universe as the big bang was not an explosion IN the universe but the explosion OF the universe.
Yes that makes me think about the 2nd Big Bang . The Universe expands And Some Day contracts to form a second Big Bang. But is it a 2nd Big Bang ? How many Big Bag Could have been caused. we cannot say This is a second Big Bang . Because it is the Explosion of Universe . It makes me feel THE Time is Like INFINITY.

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#### ramparts

##### Guest
Actually, the prevailing consensus (since we've discovered the acceleration of the universe) is that the universe is expanding too quickly to ever collapse, so it'll just expand out forever.

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#### vividasday

##### Guest
Regarding E=MC ....My self wander.

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#### MeteorWayne

##### Guest
You have a very high pointless post ratio....

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#### SubductionZone

##### Guest
alphachapmtl":4156gout said:
E^2 = p^2 c^2 + m^2 c^4 is the correct equation.

At rest, this becomes E = m c^2.

The mass m is constant, it does not change with speed, it is sometimes called the rest mass.

If you accelerate a proton, energy goes into a faster proton, it does not go into matter.

Not true. An accelerated proton has more mass. It is very hard, if not impossible, to measure the gravitational attraction of one proton. But there is another way that you can show that energy does affect rest mass. The nuclear binding energy affects the mass of a nucleus. That is most obvious when you split a uranium nucleus. The mass of all of the daughter products is less than the mass of the original nucleus.

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#### Strax

##### Guest
Speedfreak- if someone has already told you this, i am sorry for stating it again, but if light hasnt reached us yet it is probably because of billions of planets in the way and dark matter that it has to travel through, if you think about it, the light has to avoid planets, dark matter, black holes, asteroids, comets, etc just to get to us. that proves that 1. dark matter is rather scarce if we see as many stars as we do, and 2. that there is so much out there in space that it blocks out an infinite amount of stars.

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#### origin

##### Guest
Strax":2ouv8pky said:
Speedfreak- if someone has already told you this, i am sorry for stating it again, but if light hasnt reached us yet it is probably because of billions of planets in the way and dark matter that it has to travel through, if you think about it, the light has to avoid planets, dark matter, black holes, asteroids, comets, etc just to get to us. that proves that 1. dark matter is rather scarce if we see as many stars as we do, and 2. that there is so much out there in space that it blocks out an infinite amount of stars.

The whole point of dark matter is that is does not interact with matter, such as electrically, so by definition it would not interact with light.

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#### OleNewt

##### Guest
The whole point of dark matter is that is does not interact with matter, such as electrically, so by definition it would not interact with light.

It interacts gravitationally, which is how we discovered that dark matter "exists". Light and matter were going places in ways that a pure regular-matter scenario couldn't account for (faster rotations, wrong center of gravity, etc). Beyond knowing it's there we have yet to actually find any, so we probably can't rule out the strong/weak nuclear forces--if we can't see it, there's no guarantee we'd see the points of bonding (assuming we can see such things now among regular matter).

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#### origin

##### Guest
OleNewt":2deacc8t said:
The whole point of dark matter is that is does not interact with matter, such as electrically, so by definition it would not interact with light.

It interacts gravitationally, which is how we discovered that dark matter "exists".

Yes that was rather dumb of me - I meant dark matter does not interact except gravitaionally.

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#### Tumba

##### Guest
Mordred":17ycsvq1 said:
Ok were all familiar with the equation however I have some questions on this. I once read that any excess energy that drives a proton at the speed of light will convert to matter. This if I'm correct limits the proton at the speed of light.
Is this in fact a correct interpretation if so the one question I've always asked since reading that is, What form of matter does it form?
A more philisophical question I've always had on the observable. If the only way to measure something is through observation would we not claim that that is the absolute speed?
One good example is what we describe as the beginning of the universe with regards to seeing into the past. Light is our only way to see events that far back into the past. As the light has not reached us yet before that point. Is not calling that the beginning merely a mistake due to whats observable?

I do not understand why people always look to the center of the universe, and call it the begining.
The light from the begining of the universe has already passed us by. To look to the center of the universe, is to be looking at the future. I have tried to reason my thoughts on this subject, but this is the only way I can believe it to be true.

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#### Mordred

##### Guest
You are correct that the light from the beginning would have passed us by.
my biggest problem is that due to never being able to visually detect something FTL other than cause and effect. We define space time accordingly stating that light is the fastest speed. How many times have we read papers stating this particle or that thoeretical particle moving backward in time. One candidate is the theoretical tachyon particle. This would lead to a causee before event paradox. but here is a neat concept seeing as to how the universe is expanding and wil eventually expand FTL and yet light just not change speed regardless of space time its quite possible we will catch up to that light.

T

#### Tumba

##### Guest
Mordred":2ridzrxs said:
You are correct that the light from the beginning would have passed us by.
my biggest problem is that due to never being able to visually detect something FTL other than cause and effect. We define space time accordingly stating that light is the fastest speed. How many times have we read papers stating this particle or that thoeretical particle moving backward in time. One candidate is the theoretical tachyon particle. This would lead to a causee before event paradox. but here is a neat concept seeing as to how the universe is expanding and wil eventually expand FTL and yet light just not change speed regardless of space time its quite possible we will catch up to that light.

I don't have any links at the moment. But do have some information stored. I will have to do some reading to find the information I'm refering to.
But the speed of light is effected by gravity.

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#### ramparts

##### Guest
Tumba":1vbn7iqu said:
I don't have any links at the moment. But do have some information stored. I will have to do some reading to find the information I'm refering to.
But the speed of light is effected by gravity.

Factually false, unfortunately - either you're misremembering your links or they're just wrong! It's a pretty basic fact of physics that the speed of light is a constant in all frames, and that includes different gravitational fields.

T

#### Tumba

##### Guest
ramparts":2xmgd6yk said:
Tumba":2xmgd6yk said:
I don't have any links at the moment. But do have some information stored. I will have to do some reading to find the information I'm refering to.
But the speed of light is effected by gravity.

Factually false, unfortunately - either you're misremembering your links or they're just wrong! It's a pretty basic fact of physics that the speed of light is a constant in all frames, and that includes different gravitational fields.

How can gravity bend light around a gravitational field, and not change its speed?

Edit: I'll rephrase that. Gravity causes light to no travel in a straight line, therefor changing the lenght of time it take us to see an event. :shock:

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