By Brad Rodgers (P1930) on Wednesday, January 26,
2000 - 09:56 pm:
I have recently noticed a series of problems that seem to occur
within euclidean geometry. And, I can find no seemingly logical way to avoid
a failure of the system of euclidean geometry. So, I must ask for help and
ask that you find out what mistakes I have made in my study.
I first wish to outline euclid's errors at an infinite level. Generally, when
one thinks of parallel lines, one thinks that they would never intersect. But,
would not these lines intersect at infinty. The short answer is YES. If one
takes such a result and "plugs it in" the law of sines, one gets a theorem
that looks like this.
Where: a=infinite side of a triangle b=other infinite side of a triangle c=a finite side of a triangle
a/ sinA = b/ sinB = c/ sinC
¥/1 = ¥/1 = 1/ sinC
and if A=90, B=90, C=0
Therefore ¥= 1/0
There is much more to this paper, but I would much rather write it once I
have heard your thoughts on this section of the paper.Thanks.
By Dave Sheridan (Dms22) on Wednesday, January 26,
2000 - 10:40 pm:
There is no problem here. As far as I am aware,
Euclidean geometry has no known inconsistencies. It is an unfortunate
consequence of logic that we can not use the axioms to tell whether the
theory is consistent, but we have no evidence to suggest that it is not.
Infinity is a concept. It is not a number. Let me repeat that.
Infinity does not behave like normal numbers. If it did, you would
find that infinity+1 existed, and more interestingly, so would infinity-1. The
former of these can be made sense of with the use of ordinal arithmetic, but
the latter is meaningless.
When we speak of infinity, it is just a convenient shorthand for what we call
limiting behaviour. Any expression you have seen which involves the infinity
symbol is actually claiming something different. Let me demonstrate. A cat sits at the end of a table. Every second it jumps half the
distance to the end of the table. The cat only reaches the other end after an
infinite number of seconds. This statement is not well formed, because it implies that infinity is a
number. What we actually mean is that the cat can be arbitrarily close to
the end of the table, but it takes longer and longer to be within smaller
distances of the end. If you simply "plug infinity" into the time of this
problem, you do find that the cat has reached the end of the table. That does
not justify doing so though. Often, just replacing an x with an infinity
symbol will give you lots of problems.
However, one of the earliest ways of thinking about what infinity ''is'' was to
define infinity as 1/0. The problem is that you expect this to obey the laws
of addition and multiplication. It does not, because they only apply to
finite numbers.
I defy you to draw a triangle with infinite sides. There is no ''point at
infinity'' in Euclidean geometry, explicit or implicit, just as there is no
number infinity on the real line. So you can't make parallel lines meet.
In summary, you can't use infinity like other numbers. It represents a limit,
no more and no less.
Let me give one final example, which demonstrates that we can't just ''plug
infinity in'' when we feel like it.
Here's a sequence of numbers. X1=1 X2=1-1 X3=1-1+1 X4=1-1+1-1 and so on. What is the value of Xinfinity?
Well, since we can pair off every +1 with a -1, we conclude that
Xinfinity=0. That is, we write Xinfinity=(1-1)+(1-1)+(1-1)+...=0. However, we could also write Xinfinity=1+(-1+1)+(-1+1)+(-1+1)+...=1. Therefore algebra itself doesn't work!
The actual answer is that Xinfinity does not exist. We can't just plug
infinity into the subscript, because that assumes that there is a unique
value which could be taken. So it was not the laws of arithmetic which are to
blame, it is our assumption that infinity can be used like any other
number.
I hope this has been helpful. If you don't understand any of this, or would
like to know more, please write back. If you have any problems with
Euclidean geometry which do not involve using infinity like a real number,
I'd be interested in hearing about them.
-Dave
By Brad Rodgers (P1930) on Thursday, January 27, 2000
- 01:13 am:
Thank you, this has been of great help. As I am only 14, I am
denied access to many resources to check some of my work. But, I do have one
other part which I must add to my work. If one considers the reciprocal of
infinity, 1/¥, You will notice that this number is equal to 0. We can
show this by observing the fact that a decimal place really means divide the
number by ten to the power of the amount of places the number goes out past
the decimal place and you have the denominator of a fraction whose numerator
is 1( this is extremely wordy and if you do not grasp what I am saying, which
I almost don't, go on- you probably know what a decimal place means-This is
phrased very poorly.) Therefore 1/¥ = 1-.9(repeating). Thus
1/¥ = 1/1-(1/9+8/9)=0. Couldn't this 1/¥,which equals 0, number
multiply so that an area becomes larger than its supposed value, 1 dimension
becomes 2, and a line becomes a curve. And, if not, how would anything form
from a system starting with points as its base.
By Dave Sheridan (Dms22) on Thursday, January 27,
2000 - 11:54 am:
I'm glad you appreciate this discussion! Right,
onto your next point. You can think of 1/infinity as equal to 0, since
this is well defined. Let me explain. Infinity represents the limit as numbers get as large as possible. So look at
natural numbers, and see how 1/n behaves for larger and larger numbers n.
It's consistent - 1/n becomes smaller and smaller, so that if you want it to
be smaller than 0.000000000001 (say), you can find a large number m so that
1/n is smaller than this number for every n> m. Can you tell in this
case what m should be? It's this consistency which allows us to say that the
limit of 1/n as n becomes larger and larger ("n tends to infinity") is equal
to 0. We may write this as 1/infinity=0, but that's just shorthand for the
above statement.
In this sense, you might say that infinity*0=1 (since infinity ''is'' 1/0 or
from above, 0 ''is'' 1/infinity). You'd be wrong...depending on what you mean
by it. Unfortunately, even infinity isn't safe when mathematicians are around.
There are various infinities (infinitely many of them in fact!) all of
which are ''infinite''. I won't go into that though. Unless you want me
to.
So, how do we get anything from a system which starts with points? At this
point, I'm not sure that you know what the axioms of Euclidean geometry are.
Please tell me what you understand about this system, and I'll explain if
you've been told a simplified version, or whatever. In ''real'' Euclidean
geometry, there are both points and lines, which obey certain laws. For
example, there is a unique line through any two points. So we already have
1 dimensional objects. You can make a curve from many lines, and I'll go into
the topology of this if you like.
I don't understand how you can multiply an area into a bigger one though.
Remember, multiplying anything by 0 reduces it to zero. You can't then
divide by zero to get the number you first thought of - that would be
"plugging infinity in" to an equation without checking that it first worked.
Remember, 1/0 can be thought of as infinity, so dividing by 0 is similar to
multiplying by infinity. This would of course cause problems - multiply
anything by infinity and you'll get infinity (except perhaps zero). I hope
that makes sense.
Give me a concrete demonstration of something you don't understand, and I'll
try to explain how it actually works.
Hope to continue this soon,
Dave
By Brad Rodgers (P1930) on Thursday, January 27,
2000 - 11:27 pm:
As I have been told, a line forms from an infinite series of
points; however it is becoming increasingly apparent to me that this is not
the case. Please let me know if the above statement is correct. I think that
it must be.
However, here is a completely different thought. If we were to take this
argument into the realm of physical science, it would be impossible for a
universe to arise from nothing, and there would have to be a limit on the
minimum area that can be achieved in our universe. Hence quantum mechanics
is not the only thing that "ruins" spacetime at very small level, and our
new theory of quantum gravity must involve a minimum area of this sort.
And, I think that even multiply 0 by infinity can equal infinity:
¥/¥ = ¥×¥/¥ = ¥
By Dave Sheridan (Dms22) on Friday, January 28, 2000
- 12:12 am:
A line can be thought of as infinitely many
points, but there are uncountably many (you may think of a line as the real
numbers, each point being a number). Thus it isn't a sequence of points; it's
far more than that. This is an easy way to think of it. But Euclidean
geometry does not state that this is the case; it is merely something you
can make sense of using the theory. Lines are objects, points are objects,
and there are laws about how objects behave. That's it. Any more than that
is an inference.
Brad, I don't believe you can cancel in that way. Here, let me show you that
2=1: 2*0=1*0. Therefore, dividing by zero, 2=1. That is, essentially, your argument.
Spot the flaw.
I'll write more tomorrow.
-Dave
By Brad Rodgers (P1930) on Friday, January 28, 2000 -
01:11 am:
Yea, that's because I used infinity as an integer, which is
incorrect. The point is that when infinity is used, like 0, to multiply, all
defineability is lost . But, if a line, thus line segment, has infinite
points, then a line can just naturally-because infinity has different values
which( I think) are equivalent- add more points to it and become another
dimension. Perhaps I am missing something though.
Also on another subject matter, can you reccomend a good book to learn
calculus from- so far I have not been able to find one and I cannot take that
course for four more years.
Thanks for your patience,
Brad.
By Dave Sheridan (Dms22) on Friday, January 28,
2000 - 11:26 am:
In that case, I agree. You can't put
infinity into any equation and just expect it to work.
Ok, infinity doesn't have different values. The problem is that your current
definition of "value" is unsuitable for dealing with infinity. It works fine
for finite numbers, but breaks down if you plug infinity in. So the only way
to deal with infinity is to look at cardinality (or ordinality, which is even
more complicated). How many integers are there? How many even integers are
there? The answer to both questions is "countably infinitely many", ie
the
same cardinality. That is to say, our new definition of value says that
despite the feeling that there should be "half" as many even integers as
integers themselves, half of infinity is still infinity so there are the same
amount. How do we show this? We simply show that we can pair off every
integer with an even integer (by multiplying by two). Since we can pair
off every one of them simultaneously, they have the same cardinality.
Right, now you need to know that the cardinality of a line is the same as the
cardinality of the plane. That is, if you're one dimensional or two
dimensional, you have the same cardinality. So you don't need to ''add''
more points, just rearrange the ones you have. Clearly this is an odd concept,
and to be able to do this requires some very strange operations which are not
physically possible, but mathematically they're feasible (and indeed there's
a result which says that you can take a sphere, break it up into finitely
many pieces, reassemble these pieces after rotating and translating them, and
you'll have two spheres with identical volume to the original one... Something
out of nothing!)
How do you show that an extra dimension doesn't increase things? I'll give
you the general idea but it's a little complicated. First of all, when
dealing with cardinals, we find that multiplication works again! There
are a couple of extra rules though. When you have an infinite cardinal c
and an integer n, nc=c. Similarly, if you have two infinite cardinals, c
and d, where d> c (one will always be larger than the other unless they're
the same cardinal), then cd=d. Similarly, dd=d (infinity x infinity=infinity,
but this preserves the cardinal we're dealing with). The only thing which we
can't do is 2d. This will always produce a larger cardinal than d (and you
shouldn't be surprised to learn that 2d is the same as 3d or even dd).
Proving this is not too difficult when you have the correct framework, but
I won't go into that. If you believe me on this, the result is easy.
The cardinality of the real line is c (say), so what's the cardinality of
the plane? Well, every point on the line is associated with a whole line -
that's what we mean by (x,y) co-ordinates. So there are c x c points in the
plane. But c x c=c, so there are the same "number" of points in the
plane as there are in the line. Similarly, any number of dimensions up to c
of them (try to understand what c dimensions even means!) will have the
same number of points.
Ok, I'd better stop there in case I'm really confusing you! I'll explain in
more detail if you like - let me know what you don't understand.
Hope this remains interesting,
-Dave
By Brad Rodgers (P1930) on Friday, January 28, 2000
- 06:37 pm:
I think actually understand this. But the question I don't
understand is why are the equations for gravity and other forces different
for different dimensions if mathematically they can be considered to be the
same. I believe that to avoid this , especially in the physical universe, a
system of a minimum area, instead of points, is required. But, in a pure
mathematical sence, such a thing is not needed. But, maybe I am missing
something again - but if not I would appreciate it if you would explain
this concept to a physics prof (if you know one) to further the notion of a
new theory needing a minimum area.
Thanks,
Brad
By Brad Rodgers (P1930) on Friday, January 28,
2000 - 06:41 pm:
By the way, I would like if you would go into more detail- but I
think I understand this because I have read Hilbert's (I think that's his
name) work.
By Dave Sheridan (Dms22) on Saturday, January 29,
2000 - 10:51 am:
This is where you learn that cardinality is not
the whole story. Would you say that the positive real numbers are identical
to the real line? Well, the positive numbers have an endpoint (0) but the
whole real line has no such point. This is some extra ''structure'' which the
positive numbers have. Likewise, the rationals have the same cardinality as
the integers, yet we can list the integers in a list of increasing size. We
can't do that for the rationals, although we can list them (at least
theoretically).
So, what are we missing? Lots acutally. Size is just the start. Things like
lines have an inherant ordering - choose a direction on a line segment, and
say that one point is "bigger" than another if it's further along in that
direction. This ordering is the one you're used to for the real numbers.
However, the same ordering can't be applied to the plane; this has extra
structure. Ordinal numbers represent this, and they act just like finite
numbers.
For example, suppose that w is the ordinal corresponding to the set of
natural numbers. Then the ordinal w+1 corresponds to a set consisting of the
natural numbers, and an extra object which is considered to be larger than
any number (call it infinity if you like). This set does not obey the normal
laws of arithmetic of course; we can't use infinity as if it were another
number. But we can consider the set as different to the set of natural
numbers which shares the cardinality.
So in a sense, infinity+1 does exist, and is different from infinity. It all
depends how much structure you allow. Can you guess what 1+infinity
corresponds to, and which ordinal that is? (Don't worry if this is all way
above your head though)
So Physics does need to determine dimensions, since they contain information w
hich we'd lose if we merely looked at size. Also, we can't manipulate
physical objects in the way we'd need to (mathematically) to be able to
change their dimension - it would require separating points and the current
belief is that there aren't even points in nature at all (they're just a
convenient way of regarding things) so we couldn't even develop the
technology to do that.
Also, dimensions are preserved by physical laws, which often helps you to
find which laws are feasible and which can't ever be the case. Have you met
dimensional analysis yet? Basically, you look at the units on both sides of
an equation and they have to match for that equation to make any sense at
all. This gives you a hint as to when to use a square law, or a cubic one
for example.
-Dave
By Brad Rodgers (P1930) on Monday, January 31, 2000 -
01:42 am:
OK-I have a few questions. First, what is an ordinal?- I think
this might help in the understanding of your above paper. Also, if points
could "rearrange" (mathematically) we would need a mechanism to prevent this-
a minimum area. So even though our new idea of spacetime requires these
because of the the incoherence of relativity and quantum mechanics, we
would need this minimum area anyway. Basically I am just trying to show
that physicists are on the right track with a minimum area theory.
Also though when I was working thinking of relativity, wouldn't the mechanics
of it force the ''infinite area'' around a black hole to act as an integer thus
destroying any framework of laws inside the black holes horizon off?
By Dave Sheridan (Dms22) on Monday, January 31, 2000
- 11:17 am:
The ordinals are a different way of looking at
numbers. We've discussed cardinals, which measure the ßize" of a set in some
way. Now, ordinals represent the ''order type'' of a set. That is, if you can
compare elements of your set, you get an ordering; two sets have the same
ordinal if their ordering is the same. Some examples are necessary. The ordinal corresponding to a set with 3 elements is the number 3. Anything
with 3 elements which you put into an ordering will have the same ordering as
(0,1,2). The ordinal representing the natural numbers is w. If you add the number
-1 to this set, this doesn't affect the ordering (there's still a smallest
element, and you can map the set into the natural numbers by adding one to
each element; this preserves the orer). However, if you add ''infinity'' to
the set, this gives a new ordering (everything is less than infinity;
previously there was no "top" element) so the ordinal changes to w+1. The integers have neither a top nor a bottom element. You can view this set
as two copies of the natural numbers (positive and negative) which do not
overlap; this leads you to conclude that the order type is w for each, or
in total w+w=w2. Note that I don't write 2w, which is the order type of the
even natural numbers (which turns out to be equal to w). [Note that there is an error here, which Dan corrects
later. - The Editor]
Ordinals behave differently from cardinals. You may add them and multiply, but
neither of these operations commutes; that is n+m is not necessarily equal to
m+n and similarly for nm and mn. However, it is of course true for finite
ordinals.
How do you generate ordinals? This is the wonderful thing which is preserved
from finite numbers. You can add one to any ordinal to produce a new one.
That is w+1, (w+1)+1=w+2, etc are all separate ordinals. You can also take
limits, in the sense that wherever you see a 1, 2, 3, ... you can replace
it with an w to get a new ordinal. So this tells us that w+1, w+2, ... , w+w
all exist. I've already said that we call w+w the ordinal w2. SImilarly, you
get w3, w4, ... ww (which is w2) and so on. You can generate every ordinal
with these operations. Interestingly, we may extend the ideas of induction
to work for ordinals as well (called transfinite induction) which is a
powerful technique for number theory and logic.
Let me know if you still have queries about ordinals. Now I still don't
understand the minimum area criterium. Please explain that to me. However,
it does not solve the problem you envisage. How much difference does it make
to remove one point from the plane? Well, the area is unchanged. In fact,
you can remove any countable set of points without changing the area; some
uncountable sets as well, but not all of them. This is part of measure
theory which is a whole other discussion (see the "Sequence of consecutive
integers" Open Discussion on nrich where I've tried to explain lots about
measure theory and its relation to probability).
As for your final question, perhaps that is the case; I'm not sure I
understand your terminology. Certainly, physical laws break down at the
event horizon and it's impossible to predict what happens in there. This is
true already, before any modifications to the theories are required.
-Dave
By Sean Hartnoll (Sah40) on Monday, January 31, 2000 -
02:14 pm:
Hi Brad. A book I found useful to learn calculus
from was "Teach Yourself Calculus", written by P. Abbot and M.E. Wardle, and
published by Hodder and Stoughton. It is part of a series of Teach
Yourself Books.
- Sean
By Dave Sheridan (Dms22) on Monday, January 31, 2000 -
11:51 pm:
Oops. Apologies for a mistake in the last
posting of mine. I stupidly wrote that the integers have as an ordinal w2.
This is clearly not true, since they are not well-ordered. One of the main
points about ordinals is that they are comparable, so a set of order w2
should have a set of order w followed by a set of order w. The integers do not
fulfill this criterion; the negative numbers with ordering « " do not have a
least element so do not have order type w. I was slighty careless with that
example.
The integers do not have an ordinal, since they do not have a least element;
however, every set has a cardinal so at least that was right. For a set of
order type w2, think instead of a set of red natural numbers and blue ones.
Every red number is automatically thought of as "less than" any blue number.
Otherwise, we use the normal comparison. This set has order type w2, since
the least element is red zero, and there are clearly two distinct orderings
of type w within the set.
Apologies for the error... I'll try to be more careful in future (and hope I
didn't make a mistake just now!)
-Dave
By Brad Rodgers (P1930) on Wednesday, February 2,
2000 - 02:08 am:
My belief that a minimum area is required rests not in the
subtraction of points, but in the addition of points. If points A and B are
on opposite ends of a line segment, and this line segment became a 2
dimensional entity through pure mathematical "force" the distance between
A and B would change; instead of simply being seperated by the vertice of a
square, they would be seperated by the diagonal of a square. And, thus all
laws of gravity using distance as a determining factor(ei: all of them)
would be "thrown off".
I think I am getting ordinals though; so thanks. But, I am still not sure
I understand them completely- Let me review: w represents the natural numbers.
It can only be changed by adding infinity to it. But, I am still not
understanding the multiplication of ordinals and some of the addition of
ordinals. But I think that this may be because I am still thinking in the
frame of mind that I use in algebra.
I am not sure that time has existed forever. There would be a point in which
time completely stopped and that would be the beginning of time(poor
phrasing again, sorry). I don't think that all the values before that
would add up to be infinity - just approaching it. But I am not well
aquainted with calculus- so I may be wrong. But, anyway our measure of
time, as we are inside the universe, is that of the universe; so if the
universe uniformly"changed its measure of time,we would too. So unless
we are observing through hyperspace , our universe is about 12 billion years
old.
And because photons are massless, relativistic mass increase( the gamma
factor, I think) does not really cause any problems with them. It is purely
a mathematical tool- not a real life entity( I may be wrong here). But if
they had mass it would. It is just that I think that the infinite predictions
for the distance from a horizon to a singularity should be embraced as
meaning that chaos becomes infinite inside of a black hole- not as an
error in general relativity, as many think.
By Dave Sheridan (Dms22) on Thursday, February 3,
2000 - 10:30 am:
I still don't think the "minimum area" concept
is necessary. Once you've imposed laws like gravity, you assume that the
system is unaffected by anything else, and see how it evolves. Points can't
spontaneously rearrange themselves and none of the physical laws you've
introduced would cause them to be so weird that the whole changes its
dimension (that's one of the requirements of a valid physical law really -
believe me, the rearrangement would have to be really weird).
Here's a way of thinking about addition of ordinals. If you have a set of
ordinality a and a set of ordinality b, you can construct a set of ordinality
a+b simply by colouring the second one blue and the first one red, and using
the order ''all red things are smaller than blue things; otherwise we can
already compare them''. So for example, 1+w consists of red 0 followed by
blue natural numbers. What's the order type of this? Well, if we called the
red 0 a blue -1 instead, we'd have the same ordering as the natural numbers
(just add 1 to everything, and this preserves order) so the set has
ordinality w. So 1+w=w. However, if we have a red set of natural numbers and
blue zero, we can't map this back into the natural numbers whilst preserving
the ordering, since we have a largest element. So w+1 is not w. Try to work
out the ordinality of some sets you know - like the integer lattice (ie both
x and y axes are natural numbers, giving you a grid - but only the positive
quadrant).
There's a similar way to think of multiplying ordinals, but I won't go into
that now.
-Dave
By Sean Hartnoll (Sah40) on Thursday, February 3,
2000 - 12:19 pm:
Hi Brad.
When you are talking about relativity, you have to be very careful to take
into account which reference frame ("point of view") you are in. So for
example, although from my frame on Earth it looks like time comes to an end
at the event horizon of a black hole, this is not true from the frame of
someone actually falling into the black hole. Someone falling in could pass
the event horizon without noticing (well, apart from getting turned into
spaghetti), although she would find it impossible to go back. She would also
fall right the way to the singularity in a finite time.
Another point is that in general relativity the concept of "force" isn't
really used. All you have is matter and spacetime. The way it works is that
matter tells spacetime how to curve (from ten equations called Einstein's
field equations) and then the curvature of spacetime tells matter how to
move (particles move along the shortest possible paths, called geodesics).
There isn't a force law like there is in Newtonian gravity, all there is is
geometry. Although it is certainly true that spacetime gets curved it will
never happen that a point becomes a line or a line an area, these are
completely different types of changes.
Finally, people have tried to come with theories involving the idea of a
minimum area. However, they have not been particularly successful. Some of
the immediate difficulties are obvious: because space and time are all mixed
up, a minimum area requires a minimum time also. Because different observers
see different things, then the mimimum area cannot be absolute. However,
there is a small length scale, the planck length, at which small
"quantum fluctuations" make it hard talk about the very concept of space.
It is in this domain that a new quantum theory of gravity is needed.
A very good book about general relativity is Kip Thorne's "Black Holes and
Time Warps: Einstein's Outrageous Legacy". The book I mentioned earlier
on Calculus is also important: calculus is the language used in all of
theoretical physics.
Hope this helps your ideas!
Sean
By Brad Rodgers (P1930) on Thursday, February 3,
2000 - 10:08 pm:
Yes, I have the book "Black Holes and Time Warps". It is indeed a
good book. But it shows very well, according to general relativity, that the
area surrounding a pre-black hole becomes infinite as the singularity gains
enough mass to become a black hole- at least according to our reference point.
This would cause a small area to become infinite; in fact even a line
surrounding the black hole would become infinite, as there are infinite
infinities in infinity( another one of my poorly phrased sentences- I
really can't do better). Perhaps this is why nature has enshrouded this area
with a cover.
As far as the idea of a minimum area criterion, perhaps I should leave the
idea of changing dimensions to demonstrate my point. As you said, a
sphere could rearrange itself into two spheres. Provided the same logic holds
for a simple line, a line of distance y could rearrange itself into a line
of distance 2y. And as a point would be a minimum area, it would be the
measure of all things. So, the distance light travels in a second could be
anything, a serious contradiction of modern physics. I think that if
mathematics expresses the physical world then a mathematically possible
way of "manuevering" these points in such a manner would translate into a
physical way of doing so.
By Brad Rodgers (P1930) on Wednesday, February 9,
2000 - 10:25 pm:
Is the above correct?
Thanks,
Brad.
By Sean Hartnoll (Sah40) on Wednesday, February 9,
2000 - 10:54 pm:
I'll get back later about the collapsing star, as I have to read
a bit first to give you a good answer.
As for the minimum area, two points. Firstly, I don't know what you mean by
"rearrange". I certainly don't think a sphere could "rearrange" itself into
two spheres. Secondly, when you say that the existence of a minimum area
would mean that the speed of light could be anything you are forgetting that
the mimimum area would also imply a minimum time. These would be related in
such a way that the speed of light would always be the same (i.e. the minimum
time would be the time it would take light to cross the minimum area).
It is hard to speak accurately about general relativity without using the
mathematics it is framed in (tensor analysis), this is the only way to state
exactly what curvature of spacetime really is. To this end I would repeat
that the best thing you could do with a view to understanding general
relativity better would be to learn as much calculus as possible.
More later,
Sean
By Anton Ilderton (Abi20) on Thursday, February 10,
2000 - 01:52 pm: Hello. About the spheres; if you assume the
Axiom Of Choice (which is basically given an infinite set of sets, you can
pick one item from each set), then the Banach-Tarski `paradox' states
that you can cut a sphere into finitely many parts (which aren't the
everyday shapes you might be expecting) and then you can rearrange them
(whereby we mean translate and rotate the shapes, standard euclidean stuff)
to form two spheres each the same size of the orginial.
The proof involves some heavy Group Theory, but this kind of thing has little
to do with General Relativity.
Anton
By Anton Ilderton (Abi20) on Thursday, February 10,
2000 - 02:10 pm:
Referring to one of the above messages
(infinite distance from an event horizon to a singularity); an object which
has passed beyond the event horizon of a black hole, irrespective of whatever
it then does, however it then tries to move, in a finite time as measured by
itself it reaches the singularity.
To put this in perspective, suppose you go and stick your finger into a black
hole. Your finger is crushed by the singularity in finite proper time, but
from your point of view (outside the event horizon) it takes infinitely long
to put your finger beyond the event horizon, so you never experience it.
Which is nice.
Anton
By Sean Hartnoll (Sah40) on Thursday, February 10,
2000 - 02:52 pm:
Okay, granted that a rearrangement of a sphere into two spheres is
possible. But the gravitational field is not going to produce a Banach-Tarski
rearrangement.
Sean
By Brad Rodgers (P1930) on Sunday, February 13, 2000
- 09:57 pm:
Please excuse the latency of my reply; for some reason I couldn't
access the boards portion of your site for a few days. When I said that a line segment of points could rearrange into a line segment
of twice the length of the original, I meant that since infinity can double
itself without a mathematical change, a line segment (measurement= infinite
points) would be equivalent to a line segment of twice its length. And because
a point would be the measure of all things, it would cause a line segment of
2y to be equivalent to y. Thus light could travel 2y in 1 second, or it
could travel 1y in 1 second. Perhaps this just shows that we can't measure
the universe in points; but wouldn't this implie that points aren't the
minimum area. Thus something without an actual area would be required for
a minimum area.
It also seems to me that the reason that the individual in the horizon would
reach the singularity in a finite period of time is because of his measuring
of time being infinite. This would allow for him to go an infinite distance
in a normal amount of time. I'm not sure if this is right, but I think
it is.
Also, I have had trouble finding that book; do you know where a good place
to find it is.
Thanks,
Brad.
By Sean Hartnoll (Sah40) on Monday, February 14, 2000
- 12:35 am:
Hi,
About the book. Full details are:
Teach Yourself Calculus, 4th Ed Abbot, P., Neill, Hugh £8.99
Series Title: Teach Yourself Publisher: Hodder & Stoughton Publishers Binding: Paperback Publication Date: 06-AUG-1997 ISBN: 0340701609
You should be able to find it at most (large) bookshops in the maths section.
Otherwise you
could call Blackwells bookshop at 01865 261381 and they send it within a
day.
Looking at a line as an infinte number number of inifinitely small points
isn't usually very helpful, because you end up with things like Zeno's
paradoxes, one of which says an arrow cannot move because to get from one
point to another it has to go through infinitely many points which would
take an inifinite time (can you see how to solve this?). You should see it
as a continuum which you can parametrise: i.e. you can label each point on
a line segment, but that point is just something that divides the line into
what is before it and what is after, it doesn't have any extension in itself.
If you look at it like this, I think the problems you are suggesing don't
arise.
About the black hole. You are looking at the problem as though our external
perspective is the "right" one whilst the person falling somehow travels an
infinite distance in a finite time. The thing is, all viewpoints are equally
valid (this is the principle of relativity) and for the person falling in
there really is only a finite distance, and this is completely real fact,
not an illusion.
Sean
By Brad Rodgers (P1930) on Monday, February 14,
2000 - 11:12 pm:
I think I understand the point concept; It is starting to make
sense to me. Also on the black holes- I'm seeing that because the time allows
for light to travel a distance in finite time, there must not be an infinite
distance.
But, I am still convinced that general relativity predicts and firmly shows
that chaos becomes infinite inside of a black hole from our perspective.But,
once one has entered the black it runs by perfectly normal mechanics. What I
believe this means is that in ordrer for general relativity to hold up, there
can be no naked singularities. This also may mean that as an object enters
the horizon( and if points do exist) he may be able to see this chaos. He
would be able to do so because several rays of light would be orbiting the
singularity at a point differenciating between chaos and mechanics. Wouldn't
this mean that if points are the building block of the universe, then at the
point of the entire universe contracting to a singularity, the known laws of
physics would change to any form( at least concerning the distance used to
determine the amount of natural force exerted on an object at a certain
distance). I'm sure I am missing something here, but I am not sure what
it is.
Along with this the idea of quantum foam as being probabalistic would have
to be dismissed. instead everything would have a probability of 1infinite
(or 0) once the singularity is entered everything is as if it is normal. Again this
makes no sense; but I think that it's true- so long as the singularity causes
our perception of the space around it to be infinite.
Also, about the book, can I find it in America. And is that number toll free
from America.
By Sean Hartnoll (Sah40) on Tuesday, February 15,
2000 - 12:10 am:
I don't about the book in the States. The number is not toll
free from America, and it'll take ages to get to you, so another approach
is required. You can get it from Amazon over the internet, go to
click here for Calculus at Amazon
I don't know what you mean by "chaos".
Sean
By Brad Rodgers (P1930) on Wednesday, February 16,
2000 - 06:37 pm:
By chaos, I mean that a distance cannot be predicted. Thus the
"quantum foam"( In this case it is more so a way for space-time to manipulate
itself without contradicicting laws) that resides within a black hole would
be unlimited in its form. Therefore, inside of the horizon, from our point of
view, their are infinite possibilities of the topology. This, in my mind, is
infinite chaos. But, seemingly, this quantum foam disappears when one enters
the horizon. I believe, that if the above idea is right, this shows that
naked singularities are not allowed. If they are, there would be several
different sets of probabilities of what is happining- a contradiction of even
quantum mechanics.
But also, if the above is correct, there would be infinite possibilities of
what is happening. I believe that this would mean that each possibility would
have a 0 caused by the placing of particles). And of course, this would mean that
from our viewpoint the area inside of a black hole has no form. I am very
confused about this result, but can find no flaw in my reasoning. The only
way I could think of avoiding this is if the probabilities of a form
occuring take the form of {1/2,1/4,1/8,....}or something of the like. Either
that or there is a flaw in my initial logic, or einstien's theory-
I'd place my bet on the first.
Please discount the second paragraph in my board before this- I realized that
if a photon has volume, there is no problem.
Brad
By Sean Hartnoll (Sah40) on Wednesday, February 16,
2000 - 07:46 pm:
Firstly, you have to be more careful in talking
about probabilities. It is wrong to say that because there are infinite
possibilities then each possibility has a 0 like saying there are infinitely many places I could be at this moment,
therefore I am nowhere.
To resolve this properly you need calculus, but the basic idea is that if
the variable can take values x, where x is a real number (like my position),
then what you have to consider is the probability of the variable being
between x and x+dx, where dx is a small increment. This probability will not
be zero. This may seem like we haven't really found what we wanted, but
remember that dx can be as small as we like.
I don't think that you can call the quantum foam "more" or "less" chaotic.
It just is what it is, random fluctuations in spacetime because when we get
small enough then small quantum fluctuations in mass produce fluctuations
in the gravitational field, i.e. spacetime.
Sean
By Brad Rodgers (P1930) on Friday, February 18, 2000
- 02:41 am:
OK- I see what you are saying; but, it still doesn't resolve all
of my problem. By showing that this type of spacetime can exist inside of a
black holes horizon, it leads one to believe that this region of spacetime
could entirely isolate itself through this type of curvature. This leads to
all sorts of problems. If you don't see what type of topology I am trying to
show, I can try to scan a picture in- it is somewhat hard to describe. This
form, however, leads one to believe that naked singularities are possible,
as a sigularity could isolate itself, thus gravitational field, while still
leaving a small amount of light to escape revealing( for a short time) the
singularity as it just began.
Thanks for all your patience
Brad
By Brad Rodgers (P1930) on Monday, February 21, 2000
- 10:38 pm:
I have to apologize; it appears my scanner isn't working.
Tomorrow I will see if I can use my school's scanners to scan an image in.
But, in case my consequences disprove this theory, I'll go ahead and state
them
I have found that it leads one to believe that naked singularities are
possible if the evaporation of Black Holes is possible. But it does arrive
at the interesting conclusion that a singularity can break off from the rest
of the universe, forming a new baby universe of it's own. This is posible
because there would be gravity still pulling on the object from the newly
formed universe. Also note that an infalling observer would arrive at this
newly formed universe.
By Sean Hartnoll (Sah40) on Tuesday, February 22,
2000 - 12:35 am:
I look forward to seing your picture. Just a
few words on what a theory is though. A physical theory involves mathematics
in order to be precise. It is not enough to argue qualitatively, or if you do
it should be backed up by a solid mathematical understanding and intuition.
What you are talking about is indeed the subject of some speculation
(formation of so called "baby universes", perhaps you have read the essay
by Hawking with this title?) and the naked singularities you describe a
similar to the singularity of the big bang (which would have been "naked").
However, to be able to produce a sceintific argument about this you need to
show how it happens within the context of the mathematics of the theory. This
is why maths is so important, it is a way of making precise the things you
want to say, and often it has surprises in store.
By Brad Rodgers (P1930) on Tuesday, February 22,
2000 - 10:07 pm:
[Failed attempt to scan picture.]
In this, the standard black hole's topology is our current understanding. New
Black Hole Topology is my theory. This theory is backed by mathematics in
that relativity specifies that the radius around black holes is infinite in
comparison to the circumference. By understanding that this is not changed by
an area "bulging in", it is very feasible to see that a portion of a black
hole can isolate itself. And, as from our perspective there is an infinite
distance to this cutoff, the force of gravity will continue for an amount
of time until vaccum flucuations cause the hole to evaporate. As far as the
cutoff of our universe to the singularity, this region would be finite and
thus shrink and form a new universe. if you have any questions about the
logic used to deduce this picture, or of the writings on the image, please
write back. If you understand my logic and see a flaw in, write back as well.
However, if you see no flaw in my reasoning, please tell of this to a
physics proffesor at your university
By Sean Hartnoll (Sah40) on Tuesday, February 22,
2000 - 10:47 pm:
I couldn't get to see your document. However,
what you are describing is something that people have studied, somewhat
speculatively. The point I must insist on is that this does not
constitute a theory. If you want to say something about what's happening
with black holes in a scientific way you need to express mathematically what
is happening to the spacetime, and here mathematically means tensor analysis,
Einstein's field equations and topology. It is not enough to draw some
pictures that look plausible, unless you have an underlying understanding of
the maths I mentioned in the previous sentence. It is really good that you're
thinking about these things and I'll be happy to answer your questions but
the best thing you could do is learn maths. Calculus is a good place to
start.
Sean
By Brad Rodgers (P1930) on Tuesday, February 22,
2000 - 11:14 pm:
So this is really just speculation moreso than a theory. I think
I can see why.But does that neccessarily prove my idea wrong. Or can it still
exist without an equation to show things about it. Just to let you know, I have just purchased that book and have started to
learn Calculus.
Thanks,
Brad
By Sean Hartnoll (Sah40) on Tuesday, February 22,
2000 - 11:36 pm:
I would like to see your picture, as I said,
I am happy to clarify conceptual difficulties you may have. The more you have
thought beforehand the easier you will find it to learn general relativity
and quantum mechnics when it comes to it. You will find in the maths a whole
new and powerful way of expressing the things you are already trying to think.
The reason equation are important, aside form being very natural, is that
they give numerical results and predictions that can be tested experimentally.
You can also say whether a page of maths is right or wrong, which you can't
really do with anything else. The maths itself, however, is useless without
ideas.
Sean
By Brad Rodgers (P1930) on Sunday, February 27, 2000
- 01:20 am: Ok, I've tried uploading the picture several times and it doesn't
appear to be working. So here's a different aproach: albeit rather crude.
In the following lines ' stands for for nothing. It is a space filler. A .
stands for a point in a curve. Unless otherwise noted all the curves extend
to infinity
CURRENTLY THOUGHT BLACK HOLE TOPOLOGY .....''''''.....''''''''''''''''''''''''''''''''''''''''.''.'''''''''''''''''
'''''''''''''''''''''''''''''.''.''''''''''''''''''''''''''''''''''''''''''''
''.''.''''''''''''''''''''''''''''''''''''''''''''''.''.'''''''''''''''''''''
''''''''''''''''''' MY THINKING
.......''''''''''.......''''''''''''''''''''''''''''''''''.''''''.'''''''''''
'''''''''''''''''''''''''''''''.''''''.''''''''''''''''''''''''''''''''''''''
''''.''''''.-infinite''''''''''''''''''''''''' ''''''''.''''''.''''''''''''''''''''''''''''''''''''''''''''.''.'''''''''''''
''''''''''''''''''''''''''''''''''..'''''''''''''''''''''''''''''''''''''''''
''''''.''.'''''''''''''''''''''''''''''''''''''''''''''.''''.''''''''''''''''
'''''''''''''''''''''''''''''.''.''''''''''''''''''''''''''''''''''''''''''''
'''..-black hole ends''''''''''''''''''''' '''''''''''''''(not infinite)
This is really rather speculative, but there is some good logical backing to
it. If I haven't already said it, I'm sorry for this approach, very very
sorry. When reading this keep in mind that the lines for the type-up are
only 51 spaces long. So rearrange these lines if you want; or I could try to
mail a picture to you if you could give me an address to a department at
your university. It would only take a week or so.
By Brad Rodgers (P1930) on Friday, April 7, 2000 -
06:20 pm:
Sorry about not getting my scanner to work( or my school's for
that matter, but I think I may have another solution. if you have access to
the newsmagazine Time, you can find a picture to my idea in the "Will we
discover another Universe?" segment of the Visions section. It is illustration
2 under reality check. this leads me to believe that this has been
discovered before; however, in the magazine, it says that this theory is
still speculative. But in the past few weeks, I have read a good deal of that
calculus book and a number of set theory books and believe that this theory
is very related to Cantor's Continuum Hypothesis and may be able to show this
very easily.
By Sean Hartnoll (Sah40) on Saturday, April 8, 2000
- 04:26 pm:
I would be interested to hear what you have to
say about Cantor's Continuum Hypothesis in relation to physics. Which edition
of Time was it? However, remember that the whoever wrote the Time article would have had a
lot of maths to back up his pictures (there is a good reason why general
relativity is not taught until the third or fourth year of university).
Maths is the fundamental difference between popular science and real
science.
Sean
By Brad Rodgers (P1930) on Saturday, April 15, 2000
- 02:36 am:
It is the April 10, 2000 edition. It is part of the visions series
and entitled ''In the Future we will...''. I do not see any page numbers
though. I believe that this is related to the CH in that if their are an
infinite number of points in a body of length, and their are an infinite
number of these bodies of length in another body of length, are their
uncountably infinite points in the larger body of lengths? I am not sure
that this is the CH, but to the best of my ability, this what I made the
word contortions in my book out to be. Anyway, if there are uncountably
infinite points, parametrisis becomes impossible. Therefore, I believe
(but am not sure of) it would be possible for the space-time leading to the
singularity to add length to itself and then "pinch off" and form an
isolated universe. This should be what the picture shows. I am sorry that
I am unable to provide the tensor analysis to show that this would be
uncountably infinite points as I am just getting through learning normal
Calculus now.
Brad
By Brad Rodgers (P1930) on Friday, June 16, 2000 -
07:23 pm:
I think I may have finally developed the mathematics to back my
no-point conjecture up. First assume that the universe is flat(therefore
doesn't curl) and is made of points. If these are true, then the sset of
points in the Universe, U, is U=c , where c is the continuum. But, Godel
has shown that c=alephx where x is undefined. This (I think) means that
parametrising is impossible to do. How then would anyone measure the number
of points in the universe. If they measured it once, then its area would
expand or decrease to another aleph above 0. This would mean that the
universe could mathematically increase its area. This leads to all sorts of
odd problems. As these are not typically seen, I believe that points do not
exist.Perhaps though, I am still not fully understanding.
Brad
By Michael Doré (P904) on Saturday, June 17,
2000 - 07:40 am:
Brad - a few points here:
If the assumptions you made at the start are true, the cardinality of the set
of points in the universe is the cardinality of the irrational set of numbers.
This is fixed. So although you don't know x where the set is alephx, this
doesn't mean the points can suddenly increase in cardinality. It just means
it is unknown how many cardinalities are below it, but this doesn't say
anything about its actual absolute size.
In fact all lengths/areas/volumes/n-D spaces have the same cardinality of
points. Independent of the size of that space. It is the irrational
cardinality. (There's a nice easy proof of this.) But this means it's
possible to take (for instance) a sphere and re-arrange the points to form
two spheres provided you accept the axiom of choice. (This is very hard to
prove though.) But the kind of transformations in operation here cannot be
done physically. The sort of transformations I'm talking about (perhaps not
the specific ones in operation here) are for instance:
Take all points which are an irrational length from the centre of the sphere
and remove them only.
I hope you can see why this is a problem physically. Between any two numbers
there are infinitely many irrational and rational numbers.
So anyway, changing in area has nothing to do with changing in cardinality,
or changing the aleph if you prefer. If you did increase the cardinality it
would be impossible to fit the points in ANY sort of space, no matter how
big, or how many dimensions.
I'm not sure what you mean by parametrising is impossible.
Anyway, as it happens I think the latest QM theories don't have points in
the universe. Length is quantised by the Planck length (if I remember
correctly, this length compared to an atomic radius is like comparing an
atomic radius to the radius of the Earth, approximately). Planck's time
quantises time - and Planck's length / Planck's time = speed of light.
However I'm not sure exactly what this means - maybe points do appear still
in the wave calculations.
Yours,
Michael
By Brad Rodgers (P1930) on Saturday, June 17, 2000 -
05:18 pm:
By Michael Doré (P904) on Sunday, June 18,
2000 - 03:34 pm:
I think there are two important points here.
1) It is true that if we let c = set of points in a Euclidean space, we
cannot determine x where c = alephx. But this doesn't mean the size of
c can change, only it's not possible to know how many other infinite sets
there are below c in size. So we don't see the amount of points on a line
changing all the time or anything like that.
2) The amount of points an object has is not directly related to its
length/area/volume etc. A 1cm ruler has the same amount of points as a 4-D
space, stretching out to infinity in all directions. This is because the
set theory definition of amount of points is to do with whether a one-one
correspondence can be established. Two sets of points are said to have the
same amount of points (or same cardinality) if you can establish a one-one
mapping between the two sets. You can always do this for any set of points
in Euclidean geometry, so we say that all lines/areas/volumes etc have the
same amount of points.
If you want a proof of that last statement, then let me know.
Yours,
Michael
By Brad Rodgers (P1930) on Sunday, June 18, 2000 -
08:53 pm:
I think I am understanding, however, if the amount of points in
all structures is the same, then how can we consider points to be a valid
part of geometry.
Also, isn't the ordinality of points in two different structures different.
However, when one switches to an infinite distance made of points, we cannot
rely on ordinality as the order is uncountable. The cardinality can also not
be told apart. Therefore, in infinite distance points are an invalid
system.
Maybe the proof you speak of would help me understand better, but I think
I am understanding why cardinality is the same for all structures.
Thanks,
Brad