Ouch
I never said I witnessed the big bang. If I gave this impression, I am sorry. But I don’t think this precludes me from talking about it.
Having said that I think your comments are valid. Sometimes I speak as though I am an expert. I am not an expert. I am just an individual interested in the origin and ultimate fate of the universe.
I stand by my explanation of the big bang which is based on my understanding of Stephen Hawking’s writings, but I agree I should have been less assertive.
JoeyBlades said
As is explained in Hyperspace, about 25 dimensions are needed mathematically to make the current equations of electrodynamics, gravity, and nuclear forces work ‘nicely’ in a mathematical matrix. When you do plug in the equations in that matrix, luckily, all but 10 dimensions ‘cancel out.’ It’s like those huge equations Einstein was working with suddenly simplifying to E=mc^2. Ummm… I personally don’t know the math to prove it. And it’s just an untested theory.
The best guess in hyperdimensional theory is that the extra dimensions exist only at the quantum (or even sub-quantum) level. Quantum mechanics holds true in a black hole (best guessing here, on the part of physicists according to their calculations) all the way up to the point of singularity. At the point of singularity, you have infinities in the equations which break the equations. So, at the point of singularity, no one knows what happens dimensionally (if there are any dimensions at all in a singularity).
You’re confusing three separate concepts:
Observation: The outside of galaxies are rotating faster than they should, which means nearby gravity, which means nearby mass. But where is that mass? This is the ‘dark matter’ that’s being looked for. It is near the galaxies somewhere (and thus, not out on the ‘edge’ of the universe).
Observation: Galaxies farther away move faster away from us than closer galaxies. This is explained by simple expansion of the universe. If space is expanding evenly everywhere, than the speed at which any two objects are moving away from each other is proportional to their distance.
E.g., let’s say I have a six inch ruler and, in one second, stretch it into a 12 inch ruler. Now put the expanded six inch ruler next to an actual 12 inch ruler. The bases are even. The one inch mark on the 6 is at the two inch mark on the 12. The six inch mark on the six is at the twelve inch mark on the twelve.
OK, now, consider any two consecutive marks on the six inch ruler that were one inch apart, they are now two inches apart. They moved apart from each other at one inch per second.
Now consider any two marks that were two inches apart, they are now four inches apart. Thus, they moved two inches per second away from each other.
The base and the six inch mark are now twelve inches apart. The moved away from each other at six inches per second.
Thus, the further apart any two points are, the faster they are traveling away from each other.
3. Is there enough mass to cause the universe to contract? Right now, we don’t see enough to cause it to contract. Maybe if we find all that dark matter, it might be enough, maybe not. And maybe there’s a lot of matter outside our view (the light from it hasn’t reached us yet, or may never reach us). Until we can actually detect enough matter that will cause the universe to contract, we will never know if there is enough or not.
Thank you for clearing some of the ignorance from my mind, I shall never view the world through clouded glasses again…
On the subject of black holes, if at the singularity the mass is at infinite density yet in an infinitely small space, wouldn’t the two cancel each other out, resulting in more-or-less equilibrium? I might be completely off the mark here, but it was just a thought that occurred to me.
If the matter is in a finite amount of space, wouldn’t that mean that there is also a finite density of matter, or is it truly an infinitely small point?
“Now be quiet before I rather clumsily knight you with this meat cleaver” - Edmund Blackadder
The problem is that when there is enough matter (a large, but finite amount), it creates enough gravity to overcome all internally repellent forces that we know of. The matter (which is finite) collapses and all of it now occupies the same point. The infinites are in the denominator which makes the space of the matter collapse into a point (and thus, infinitely dense).
All the matter is still there and still has the same gravitational pull on objects at a distance as it did when it wasn’t squeezed into a singularity. The matter is finite, the gravitational pull is finite (abeit strong enough to keep light from running away), but the space occupied by the mass has become one dimensional (according to current mathematical theories).
One point of clarification. The mass at the point of singularity that was the origin of the big bang was possibly (theoretically) infinite, but I don’t believe that serious theoretical physicist believe that the mass within black holes is at infinite density.
moriah wrote:
String theory, rather than predicting that space becomes one dimensional, says that the three space dimensions (and perhaps time) begin to “compactify” or curl up, similar to the other 6 dimensions that are believed to coexist.
Just a quick question on a subject that I was ‘debating’ last night…
How can time itself be referred to as a dimention, when time as we perceive it is merely a concept? Isn’t ‘giving’ time a dimention the equivalent of giving an immaterial idea physical form?
“Now be quiet before I rather clumsily knight you with this meat cleaver” - Edmund Blackadder
If the Universe was initially ‘pure energy’ and energy has no mass then wouldn’t that imply that at the point of the Big Bang the Universe had no mass and thus could theoretically have expanded at any velocity that it needed to (assuming that pure energy has no upper speed limit)?
Also, if a black hole has a measureable mass, and all matter and energy falling into it is converted to energy at the singularity (as no matter could survive the obscene gravitational pressure at the singularity), then doesn’t that imply that energy has a quantifyable mass?
“Now be quiet before I rather clumsily knight you with this meat cleaver” - Edmund Blackadder
All dimensions are merely conceptual frames of reference. What physical form can you attach to X-Y-Z coordinates in the vacuum of space, for instance? Since all matter in the universe is in motion, there is no static frame of reference and time is a required dimension to fully specify the position of entities relative to other entities.
Reality is a combination of space-time.
Matter creates gravity and space and movement through time. Thus, time and space and gravity are interrelated. This is the hallmark of relativity. This is the reason why light always measures at the same speed, no matter what your speed or change of speed is: everyone everywhere at everyspeed will measure light going at the same speed. Space and time contract and dilate to make it so.
Mathematically, space and time can be interchangeable.
Because of their interchangeability, time is sometimes referred to as a dimension. But we need to be clear: time not a spatial dimension.
Although in the combined space-time formula, the distinction is moot, since space-time is a single reality.
Time is not merely a concept. Time is a necessary component of mathematically representing objects in space, especially objects moving in relation to one another.
How to put this delicately… hmmmm… sorry, I can’t: Stop using Star Trek as a physics textbook.
Ain’t no such thing as ‘pure energy.’ Energy is the ability to do work. Matter has energy, gravity has energy, electromagnetic (EM) radiation (made of lightspeeding photons such as light, microwaves, and radio waves) has energy.
You’re probably thinking of EM waves as being ‘pure energy.’ EM waves transmit energy, but are not pure energy. By analogy, a hammer flying at your head also transmits energy, but is not, itself, pure energy.
But I can see where the confusion comes from. With atomic bombs, people say matter is ‘turned into energy’ (using Einstein’s E=mc[sup]2[/sup]). What they should be saying is the energy in matter is converted into other forms of energy, such as heat, kinetic (shock wave), neutron radiation (flying neutrons) and gamma radiation (high EM waves) energies.
So, in the Big Bang, we don’t have ‘pure energy’, we have ‘energy that is not in any mass’. But what form of energy was the energy of the Big Bang? And does that form of energy create gravity like mass does?
Most probably.
But, since no mathematical theory limits the speed of expansion of the universe to light speed or the amount of energy or mass available, your original question is not relevant…yet.
First of all, no one ever said that the matter becomes energy in a black hole (or more accurately, in the singularity of the black hole). People at first doubted the density of neutron stars as too dense to be possible. It could very well be possible that matter can get infinitely dense.
And the real problem is the equations. The equations become meaningless; as if the mass has become a single, one-dimensional point in space.
But, who knows what’s really happening. Maybe some force we don’t know of keeps the singularity from actually forming, and it is a very, yet finitely, dense 3-D ball. Maybe it looses it’s 3-Dness in the macro world, yet still has quantum level dimensions in the other, proposed 10 dimensions.
Now, onto the other question in here: Does ‘energy’ (EM radiation) have matter and, therefore, gravity? Well, since a photon can be attracted by gravity (photonic light can’t leave the gravitational field of a black hole); then, most likely, ‘energy’ creates gravity just like mass creates gravity. And since a huge amount of ‘energy’ can be stored in a tiny bit of matter, then the energy levels we’re familiar with (the light from a lamp, e.g.) would be creating an almost neglible amount of gravity.
OTOH, a few billion, billion, billion photons here and a few billion, billion, billion photons there can start to add up…
Hey, Matt. I finally found your debate.
Nice to know that the users on this site can be criticised and accept it as a creative opinion. However harsh. See you in Maths…
Moriah -
thanks! I’ve finally found someone who backs up one of the theories I’ve held for a long time - that energy creates (or through action generates a ‘field’ of) gravity. The argument that I used to torment people with was “since matter is in essence simply very very ‘concentrated’ energy, then doesn’t that mean that energy creates gravity?”
If this is so, shouldn’t everything in the proximity of, say a supernova (where very very dense matter is converted into energy in the form of light heat etc.) be hit not only by an energy shock wave, but also a gravitational ‘shock wave’, especially if the core of the ex-star then compresses into a black hole where energy starts ‘dissappearing’ from the measureable Universe?
Anyone??? Please??
Claymore J -
glad to see you found me, just make sure you keep your own forum ‘What shape is the Universe?’ up and running (I’m doing my best!)
“Now be quiet before I rather clumsily knight you with this meat cleaver” - Edmund Blackadder
E = m c² means energy is mass. C² is used to convert the units from energy units to mass units. In particle physics mass is commonly measured in electron-volts (units of energy). Energy has mass because mass and energy are two forms of the same thing – mass-energy. Energy has gravity just like the equal amount of mass does.
I’m not sure I agree with this statement. It certainly means that mass has energy and it also means that as you increas the energy of a particle accelerating it near the speed of light, some of the energy goes into increasing the mass. However, neither of these things means that energy necessarily is mass - just that the two are transmutable.
Again, this is a confusing, curious statement. In that energy without mass has no meaning, then whatever mass is present will have some gravity associated with it. The gravity is a function of the mass, though - not the energy, per se.
OK… Let me try this:
¢ = $ * 10² means pennies are dollar bills.
Ummm… OK, that is not true. Pennies obviously are not the same as dollar bills, but they are equivalent and 10² is the conversion factor. They are both manifestations of the same underlying thing - money.
Mass and energy are both manifestations of the same underlying thing - mass-energy.
If you add energy (in any form) to mass, you increase its mass by the equivalent amount given by E = m c².
If you convert mass to energy the gravitational force cannot simply disappear.
I still maintain that energy would exert gravity just like the equivalent amount of mass.
I am not an expert and would love to hear from anyone who can tell me if I am close or if I am way off base here.
I too, do not claim to be an expert. It’s quite possible that I’m missing some subtle part of your argument. It’s also possible that I may have my physics hat on cockeyed…
Not precisely true. If you apply a force to a mass in some direction you are applying energy. If this mass is at rest, most of this energy goes into generating velocity (or is it momentum). Relativistically, the mass will increase, but initially the increase in mass will be infinitessimal. If the mass is not at rest, but rather travelling at a velocity approaching the speed of light, then most of the energy will go into increasing the mass and very little of it will be applied to the acceleration.
The equation E=mc[SUP]2[/SUP] refers to the potential energy of a mass at rest. It’s a special case of a more general equation.
Einstein started with the familiar Newtonian formula for energy:
E = 1/2(mv[SUP]2[/SUP])
Here E is the energy required to set a mass ‘m’ in motion with a velocity ‘v’. He then noted that we have to account properly for the relativistic contraction of space and dialation of time. He applied the Lorentz transformation to get the general form:
E = mc[SUP]2[/SUP] / SQRT(1 - v[SUP]2[/SUP]/c[SUP]2[/SUP])
You get E = mc[SUP]2[/SUP], only in the special case when velocity is zero (i.e. a mass at rest). (Gee I hope those equations come out right…)
What I’m hoping to demonstrate here is that the underlying function allows that energy can be applied to a mass to increase it’s velocity rather than it’s mass and that this does not violate Einstein’s observations.
Now we get down to the crux of the issue. I think what you have said is that this extra energy must somehow increase the gravitational field of the mass. I say I don’t think it does, because relativistically speaking, we can decide to say that the mass in question is stationary and that it is we (the observer) who is moving at the observed velocity in the opposite direction… this would force us to conclude that suddenly it is our own gravitational field that must be increasing.
Well, I don’t know if I’ve made my point, but my brain is starting to hurt, so I’ll leave it at that for now.
This is all very interesting, but I can’t help but notice that everyone very carefully avoided my question (or just thought it was too stupid to deserve an answer!).
To save your no-doubt over exercised index fingers from clicking even more, I’ll quote myself from my previous posting:
"Since matter is in essence simply very VERY ‘concentrated’ energy, then doesn’t that mean that energy creates gravity?
If this is so, shouldn’t everything in the proximity of, say a supernova (where very very dense matter is converted into energy in the form of light, heat etc.) be hit not only by an energy shock wave, but also a gravitational ‘shock wave’, especially if the core of the ex-star then compresses into a black hole where energy starts ‘dissappearing’ from the measureable Universe?"
I will say at this point that I said that ‘energy crestes gravity’ as at the most fundamental level, aren’t the two the same thing? Also, I thought of a ‘gravitational shock wave’ because if the energy from the explosion dissipates in all directions, then it’s cumulative gravitational effect would diminish rapidly. Wouldn’t it?
“Now be quiet before I rather clumsily knight you with this meat cleaver” - Edmund Blackadder
I think my answer was No, though it may not have been obvious. Matter creates gravity, or rather, gravity is a consequence of matter in space-time. Since matter has huge amounts of bundled potential energy, matter, energy, and gravity have a somewhat symbiotic relationship, but I don’t think it is accurate to say that energy has gravity. Again, you can add enormous amounts of energy to small particles in an accelerator and yes the mass of these particles will increase somewhat and yes the gravity of these particles will increase somewhat, but the contribution of this huge amount of energy towards gravity is an ancillery effect.
Brian Greene talks about this very thing in his book “The Elegant Universe”, except the point he makes is that the “gravity wave” would be kind of an inverse effect from what you’re suggesting. In one instant there would be a huge gravitational field from the very massive star, then there would be a great dissipation of mass which might look like the mass of the star had been suddenly reduced. He went on to say that this has not yet been observed.
BIGmattI don’t think we avoided your question. We just want to consider your premises and understand your terms. I am wondering exactly what a gravitational shock wave is.
JoeyBlades disagrees with “energy has gravity”
To defend “energy has gravity”, I propose the following thought experiment:
Let’s take an insulating box containing matter and anti-matter moving at a constant velocity V. If the matter and anti-matter annihilate each other and become energy, then if you assume that the box loses mass the velocity must increase in order to conserve momentum. On the other hand, if we take as our frame of reference a system moving with velocity V. The box must remain at rest relative to the frame of reference (Since the monemtum will remain zero.) Therefore it seems that the (inertial) mass cannot be lost when the mass becomes energy. Inertial mass is gravitational mass. Therefore energy must have gravity.
Thanks for answering my question - and for clarifying your previous response. Sorry if I made you answer twice, but ‘quick as a bullet’ would have been SLIGHTLY overstating my brain yesterday.
Back to the debate - - -
All of this, of course, begs the question what IS gravity? If it’s carried by particles as quanta (gravitons?) then would the gravitons be able to instantly effect everything else in the Universe, or do they have a delayed effect like photons (ie - they take time to travel through space). I really don’t like the term ‘gravitational FIELD’ because what is a field?
If the book ‘Hyperspace’ has anything to say about it, I think it said something about forces being vibrations in the ‘other’ 6 dimentions. Any truth in this? Or am I now certifiably insane?
I agree with DrMatrix, because although as merely a college student my knowledge of physics is somewhat limited, it seems to agree with what my theories & interpretations say.
I find it difficult to conceive how, if matter is ‘interchangeable’ with energy as JoeyBlades says, then what is the critical point at which there is enough energy to create a gravitational ‘field’. Surely, as DrMatrix said, the amount of energy contained within 1kg of matter would exert the same effects as 1kg equivalent of energy (by putting it through E=mc^2), wouldn’t it? If not, WHY not?
“Now be quiet before I rather clumsily knight you with this meat cleaver” - Edmund Blackadder
