good work on the link...great picturesclfsean said:Just enjoy the scenery y'all.... it's a lot less stress to figure out & will still make you go ".......oh wow....."
http://antwrp.gsfc.nasa.gov/apod/archivepix.html
Black holes, cosmos, and martial arts
- Thread starter DeLamar.J
- Start date
Oh no problem... it's one of my daily visits in the AM after checking email & boards... it sets perspective for the day.
T
the_kicking_fiend
Guest
Flatlander said:
As a physicist I have to step in on this debate! Some of the things being said are a little confused. Physicists believe that the universe is not infinite, but due to the curvature of space-time, actually probably meets itself like a sphere. In other words, if you travel in one direction long enough you will come back to where you started.
You say the Big Bang and a black hole are manifestations of the same thing... what thing? I don't believe this is an accurate desciption of reality, black holes exist after the death of a super massive star and a phenomenon due to gravity. The Big Bang was so energetic gravity did not play a key role, the Big Bang to me is very different because it represents the beginning of everything. Despite, popular belief, a black hole is not the end. Black holes evaporate over aeons into Hawking Radiation due to quantum fluctuations over the event horizon. The universe is likely to end up as a froth of highly dispersed low level radiation than anything dramatic.
bignick said:
Time will never stop onboard a spaceship that you're travelling on, no matter how fast you travel practically, theoretically or otherwise. It seems an obvious step forward to make this assumption but it would require infinite energy to do so, this is impossible. The fact it is impossible means that asking what would happen here is meaningless.
However, one particle does travel at this speed, it is the photon, light. For light, time does no have no meaning. It doesn't leave a destination and then arrive later on, it simply exists in 4-dimensional space time on a certain set of co-ordinates. But for us, we see the light leaving at t=0 and arriving at t'=x/c. The light doesn't exist everywhere, or our eyes would be burning quite badly.
d
hey...thanks for the info....i've taken some physics...but my knowledge of a lot of this stuff is extremely limited....ok....now that i have someone on here to question....about the photon...
here is a particle and yet it travels at the speed of light, as stated, anything with mass cannot travel the speed of light because of the infinite amount of energy involved...
how can the photon, since particles have mass...travel at the speed of light...where does the dual nature(wave,particle) of light fit in?
here is a particle and yet it travels at the speed of light, as stated, anything with mass cannot travel the speed of light because of the infinite amount of energy involved...
how can the photon, since particles have mass...travel at the speed of light...where does the dual nature(wave,particle) of light fit in?
Flatlander
Grandmaster
The photon has no mass, Nick. That's why it can travel the speed of light. Particles of matter have mass, but the photon is not matter, it is energy.
The dual nature of photons arises from the way it behaves under certain conditions. Photons will behave either like particles or waves, depending on how they are observed.
Zepp
Master of Arts
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Flatlander said:
Though according to the Heisenberg Uncertainy Principle, the very act of observing a particle changes its behavior.
Wow, look at me! I remember something from physics!
Yes, the uncertainty principle really only applies when trying to determine the position or velocity of a particle...
you can know one but not the other...because observing changes one or the other...
you can know one but not the other...because observing changes one or the other...
T
the_kicking_fiend
Guest
Going back to the question about the photon. A photon is a fermion and to say it has no mass is incorrect. A photon has no *rest* mass, as in when it is stationery (which doesn't happen except in some unusual Bose-Einstein condensates). When a photon is moving, it has energy, and since energy IS mass, it has a mass. This can eb easily shown practically by considering lasers that are used in industry and research which exert a force on an object due to the momentum of light particles. For light to have momentum it must have a mass.
Any particle that has no rest mass can travel around at c if it likes, although massless particles are uncommon.
As for Heisenberg's Uncertainity Principle... most people take this to mean we can't knwo what's going on in at atom or make any kind of precise calculations about the state of an atom. However, we can find eigenvalues of the equations of energy, momentum, spin, etc which means we can precisely know this value. However, say we know the eigenvalue of momentum, we cannot simulateously find an eigenvalue for the equation of position.
It is better to think of it in this theoretical way than experimentally. Otherwise it suggests that the reason we can't know momentum and position simultaneously is due to the experimenters designing an experiment which isn't good enough to find both. This isn't the case, it is simply impossible mathematically and physically to know both to a high degree of accuracy at the same time.
I find it interesting that this underlying law of physics, closely related to probabilities, means that the future is completely uncertain and unpredictable. The future is not written. Fate it seems, is just a fabrication of the human mind.
d
Any particle that has no rest mass can travel around at c if it likes, although massless particles are uncommon.
As for Heisenberg's Uncertainity Principle... most people take this to mean we can't knwo what's going on in at atom or make any kind of precise calculations about the state of an atom. However, we can find eigenvalues of the equations of energy, momentum, spin, etc which means we can precisely know this value. However, say we know the eigenvalue of momentum, we cannot simulateously find an eigenvalue for the equation of position.
It is better to think of it in this theoretical way than experimentally. Otherwise it suggests that the reason we can't know momentum and position simultaneously is due to the experimenters designing an experiment which isn't good enough to find both. This isn't the case, it is simply impossible mathematically and physically to know both to a high degree of accuracy at the same time.
I find it interesting that this underlying law of physics, closely related to probabilities, means that the future is completely uncertain and unpredictable. The future is not written. Fate it seems, is just a fabrication of the human mind.
d
Flatlander
Grandmaster
Sorry, but this does not make sense to me, can you clarify? My understanding is that the practical definition of mass is M = F/A. Given that E=MC2, if a photon had mass, would it not require an infinite amount of energy to accelerate it to C? It seems to me that it would be imprecise to assert that "energy is mass". Perhaps "energy contains a mass component", or, "mass contains an energy component" would be more accurate.
there is a bit of a difference between physics in the big world and working in the world of quantum physics...technically, all the standard equations we use when deailing with a lot of physical properties are wrong and give us the wrong result because they don't take into account relativity...at the low speeds and values we deal with they give a perfectly acceptable approximation...but they are still slightly off......
mass and energy are the same thing...it's as simple and complicated as that
mass and energy are the same thing...it's as simple and complicated as that
T
the_kicking_fiend
Guest
Flatlander said:
You're getting confused between two different definitions. Rest mass and (inertial) mass. Rest mass the mass a body has when it's velocity is zero in a given frame of reference. In a different frame of reference that is moving at velocity v', where v' is close to c, we will find that the mass in this new frame is m' = (gamma)m. Since gamma is always greater than one (since v'>0) then this mass m' will be greater than m.
That sounds quite confusing. To try and put it more simply, rest mass is never changing, it is simply a property of a given particle. A photon, for example, has a rest mass = 0. BUT, a photon is never stationery (excepting recent experiments in Bose-Einstein condensates) and hence its mass is never zero. Because its moving it has kinetic energy and therefore it has mass.
Many people find it hard to really understand what such a simple equation as E = mc^2 really means. It means ENERGY IS MASS and MASS IS ENERGY. hey are two manifestations of the SAME THING. You can consider, if you like, that mass is like incredibly dense energy that is so dense it appears solid, and similarly that energy is like really diffuse mass.
I hope this answers your question, don't hesitate to ask me anything else.
d
I am continually amazed by the variety of people on this board...
These are awesome definitions...and since this is an MA board I'd like to equate this to that a bit...in our school we've been fooling around with using our energy to try and move our opponent while we are in a relaxed state by using our mass and forward direction, and I find your explanation of mass as incredibly dense energy to be a great visualization for what we are exploring! It's amazing what you can accomplish when you relax and drop in the proper manner...the task of moving your opponent becomes effortless and far more effective.the_kicking_fiend said:
Thanks for posting this!
MJ
T
the_kicking_fiend
Guest
No problem, glad it found interest with you. Many scientific and religious schools have noticed that the concept of energy being the same as matter was suggested a long time before Einstein. Buddhists believed that all matter was just a form of energy.
To give it a modern day analogy, imagine looking at any point in space with a really powerful microscope. You can see the atom and the molecules, etc. Now imagine zooming in further. You can see the fundamental particles, the electrons, the quarks...
If you zoom in even further, all you will see is a sea of energy, like a foam of energy spread out across whatever point in space you look at (even in a vacuum there is large amounts of energy everywhere you look). In other words, the entire structure of the universe is in essence just a sea of energy, all the objects we see around us are just illusions in the phenomenal realm and not real at all in terms of the extreme microscopic level. And how it to say what scale is the right one?
Buddhists believe that the universe is a sea of energy (ki) and that matter (jin [i think]) is just manifestations of this energy. This sea of energy is filled with consciousness. So in other words, we are all part of the same ocean of consciousness. I find this interpretation appealling and satisfying. It is incredible to think that the relationship between matter and energy was deduced so early on in human history through simple power of thought and meditation.
d
To give it a modern day analogy, imagine looking at any point in space with a really powerful microscope. You can see the atom and the molecules, etc. Now imagine zooming in further. You can see the fundamental particles, the electrons, the quarks...
If you zoom in even further, all you will see is a sea of energy, like a foam of energy spread out across whatever point in space you look at (even in a vacuum there is large amounts of energy everywhere you look). In other words, the entire structure of the universe is in essence just a sea of energy, all the objects we see around us are just illusions in the phenomenal realm and not real at all in terms of the extreme microscopic level. And how it to say what scale is the right one?
Buddhists believe that the universe is a sea of energy (ki) and that matter (jin [i think]) is just manifestations of this energy. This sea of energy is filled with consciousness. So in other words, we are all part of the same ocean of consciousness. I find this interpretation appealling and satisfying. It is incredible to think that the relationship between matter and energy was deduced so early on in human history through simple power of thought and meditation.
d
Adept
Master Black Belt
Now, if we could just find a way to detonate humans...bignick said:
More cool and interesting thoughts. :asian: I am amazed and humbled by things I've seen an Aikido master do in terms of using his ki to redirect his opponents. I need to still find the key to unlocking my ki though LOLthe_kicking_fiend said:
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