WELCOME TO YOUR BLOG...!!!.YOU ARE N°

What is reality? (Editado para facilitar la lectura)‏


Editorial
Reality: ineffable, but impossible to forsake
New Scientist  01 October 2012. Magazine issue 2884. 


Do we make reality, or does it make us? 
Probe the existence of the universe's supposed building blocks 
- quarks, electrons, neutrinos and the rest - 
and you eventually end up back in your own mind. 

Alternatively, discount everything human 
and settle for "a world without us" 
- a reality that might also be unknowable by us 
(see "Reality: The bedrock of it all").

These options are as viscerally unsettling 
as they are intellectually challenging. 

Other possibilities 
- that we live inside a video game, 
say, or a hologram - 
are hardly any more comfortable.

But forsaking the notion of reality is not an option, either. 

Quantum mechanics may be ineffable, 
but it still makes electronics work. 

Wars may not "exist", but they still kill people. 

The wonder of the human condition 
is that to us, quarks are real. 
And so is compassion.

When you woke up this morning, 
you found the world largely as you left it. 

You were still you; 
the room in which you awoke 
was the same one you went to sleep in. 

The outside world had not been rearranged. 

History was unchanged 
and the future remained unknowable. 

In other words, you woke up to reality. 

But what is reality? 

The more we probe it, 
the harder it becomes to comprehend. 

In the eight articles on this page we take a tour 
of our fundamental understanding of the world around us, 
starting with an attempt to define reality and ending 
with the idea that whatever reality is, it isn’t what it seems. 

Hold on to your hats.

• DEFINITION

Reality: The definition
New Scientist 01 October 2012 
by Jan Westerhoff
Magazine issue 2884. 

Even trying to define what we mean 
by "reality" is fraught with difficulty

What do we actually mean by reality? 

A straightforward answer 
is that it means everything 
that appears to our five senses 
- everything that we can 
see, smell, touch and so forth. 

Yet this answer ignores 
such problematic entities as electrons, 
the recession and the number 5, 
which we cannot sense 
but which are very real. 

It also ignores phantom limbs and illusory smells. 

Both can appear vividly real, 
but we would like to say 
that these are not part of reality.

We could tweak the definition 
by equating reality with what appears 
to a sufficiently large group of people, 
thereby ruling out subjective hallucinations. 

Unfortunately there are also 
hallucinations experienced by large groups, 
such as a mass delusion known as koro, 
mainly observed in South-East Asia, 
which involves the belief 
that one's genitals are shrinking back into one's body. 

Just because sufficiently many people 
believe in something does not make it real.

Another possible mark of reality 
we could focus on is the resistance it puts up: 
as the science fiction writer Philip K. Dick put it, 
reality is that which, if you 
stop believing in it, does not go away. 

Things we just make up 
yield to our wishes and desires, 
but reality is stubborn. 

Just because I believe there is a jam doughnut 
in front of me doesn't mean there really is one. 

But again, this definition is problematic. 

Things that we do not want to regard as real 
can be stubborn too, as anyone 
who has ever been trapped in a nightmare knows. 

And some things that are real, 
such as stock markets, 
are not covered by this definition 
because if everyone stopped believing in them, 
they would cease to exist.

There are two definitions of reality 
that are much more successful. 

The first equates reality 
with a world without us, 
a world untouched 
by human desires and intentions. 

By this definition, 
a lot of things we usually regard as real 
- languages, wars, the financial crisis - 
are nothing of the sort. 

Still, it is the most solid one so far 
because it removes 
human subjectivity from the picture.

The second equates reality 
with the most fundamental things 
that everything else depends on. 

In the material world, 
molecules depend 
on their constituent atoms, 
atoms on electrons and a nucleus, 
which in turn depends 
on protons and neutrons, and so on.

In this hierarchy, 
every level depends 
on the one below it, 
so we might define reality 
as made up of whatever entities 
stand at the bottom 
of the chain of dependence, 
and thus depend on nothing else.

This definition 
is even more restrictive 
than "the world without us" 
since things like Mount Everest 
would not count as part of reality; 
reality is confined to the unknown foundation 
on which the entire world depends. 

Even so, when we investigate 
whether something is real or not, 
these final two definitions 
are what we should have in mind.

________________________________

Jan Westerhoff is a philosopher 
at the University of Durham 
and the University of London's School 
of Oriental and African Studies, 
both in the UK, and author of 
Reality: A very short introduction 
(Oxford University Press, 2011)

• STANDARD MODEL OF PARTICLE PHYSICS

Reality: The bedrock of it all
New Scientist  01 October 2012 
by Valerie Jamieson
Magazine issue 2884.


Can we explain reality purely in terms of matter and energy?

Is anything real? 

The question seems to invite only one answer: 
of course it is. If in doubt, try kicking a rock.

Leaving aside the question 
of whether your senses can be trusted, 
what are you actually kicking? 

When it boils down to it, not a lot. 

Science needs remarkably 
few ingredients to account for a rock: 
a handful of different particles, 
the forces that govern their interactions, 
plus some rules laid down by quantum mechanics.

This seems like a solid take on reality, 
but it quickly starts to feel insubstantial. 

If you take a rock apart, 
you'll find that its basic constituent is atoms 
- perhaps 1000 trillion trillion of them, 
depending on the rock's size. 

Atoms, of course, 
are composed of smaller subatomic particles, 
namely protons and neutrons 
- themselves built of quarks - and electrons. 

Otherwise, though, 
atoms (and hence rocks) 
are mostly empty space. 

If an atom were scaled up 
so that its nucleus 
was the size of the Earth, 
the distance to its closest electrons 
would be 2.5 times the distance 
between the Earth and the sun. 

In between is nothing at all. 

If so much of reality 
is built on emptiness, 
then what gives rocks 
and other objects 
their form and bulk?

Physics has no problem 
answering this question: electrons. 

Quantum rules dictate 
that no two electrons 
can occupy the same quantum state. 

The upshot of this is that, 
no matter how hard you try, 
you cannot cram two atoms 
together into the same space. 

"Electrons do all the work 
when it comes 
to the structure of matter 
we see all around us," 
says physicist Sean Carroll 
at the California Institute of Technology in Pasadena.

That's not to say the nucleus is redundant. 

Most of the mass of an atom 
comes from protons and neutrons 
and the force binding them together, 
which is carried by particles called gluons.

And that, essentially, is that. 

Electrons, quarks 
(mostly of the up and down variety) 
and gluons account for most 
of the ordinary stuff around us.

But not all. 

Other basic constituents of reality exist too 
- 17 in total, which together comprise 
the standard model of particle physics.  


The model also accounts for the mirror world 
of antimatter with a complementary set of antiparticles.

Some pieces of the standard model are commonplace, 
such as photons of light and the various neutrinos 
streaming through us from the sun and other sources. 

Others, though, do not seem 
to be part of everyday reality, 
including the top and bottom quarks 
and the heavy, electron-like tau particle. 

"On the face of it, they don't play a role," 
says Paul Davies of Arizona State University in Templeton. 
"Deep down, though, they may all link up."

That's because the standard model 
is more than a roll call of particles. 

Its foundations lie 
in symmetry and group theory, 
one example of the mysterious connections 
between reality and mathematics 
(see "Reality: Is everything made of numbers?").

The standard model is arguably 
even stranger for what it doesn't include. 

It has nothing to say 
about the invisible dark matter 
than seems to make up 
most of the matter in the universe. 

Nor does it account for dark energy. 

These are serious omissions 
when you consider that dark matter 
and dark energy together comprise 
about 96 per cent of the universe. 

It is also totally unclear 
how the standard model 
relates to phenomena 
that seem to be real, 
such as time and gravity.

So the standard model 
is at best a fuzzy approximation, 
encompassing some, but not all, 
of what seems to comprise physical reality, 
plus bits and pieces that do not. 

Most physicists would agree 
that the standard model 
is in serious need of an overhaul. 

It may be the best model 
we have of reality, 
but it is far from the whole story.

________________________________

Valerie Jamieson 
is New Scientist's features editor


• MATTER

Reality: Is matter real?
New Scientist  26 September 2012 by Jan Westerhoff
Magazine issue 2884.

It's relatively easy to demonstrate 
what physical reality isn't. 
It is much harder to work out what it is

Nothing seems more real 
than the world of everyday objects, 
but things are not as they seem. 

A set of relatively simple experiments 
reveals enormous holes is our 
intuitive understanding of physical reality. 

Trying to explain what goes on 
leads to some very peculiar 
and often highly surprising 
theories of the world around us.

Here is a simple example. 

Take an ordinary desk lamp, 
a few pieces of cardboard 
with holes of decreasing sizes, 
and some sort of projection screen 
such as a white wall. 

If you put a piece of cardboard 
between the lamp and the wall, 
you will see a bright patch 
where the light passes 
through the hole in the cardboard. 

If you now replace the cardboard 
with pieces containing 
smaller and smaller holes, 
the patch too will diminish in size. 

Once we get below a certain size, however, 
the pattern on the wall changes 
from a small dot to a series 
of concentric dark and light rings, 
rather like an archery target. 

This is the "Airy pattern" 
- a characteristic sign of a wave 
being forced through a hole.

In itself, this is not very surprising. 
After all, we know that light is a wave, 
so it should display wave-like behaviour.

But now consider what happens 
if we change the set-up of the experiment a bit. 

Instead of a lamp, we use 
a device that shoots out electrons, 
like that found in old-fashioned TV sets; 
instead of the wall, we use 
a plate of glass coated with a phosphor 
that lights up when an electron strikes it. 

We can therefore use this screen 
to track the places where the electrons hit. 

The results are similar: with sufficiently 
small holes we get an Airy pattern.

This now seems peculiar: 
electrons are particles located 
at precise points and cannot be split. 

Yet they are behaving like waves 
that can smear out across space, are divisible, 
and merge into one another when they meet.

Perhaps it is not that strange after all. 
Water consists of molecules, 
yet it behaves like a wave. 

The Airy pattern may just emerge 
when enough particles come together, 
whether they are water molecules or electrons.

A simple variant of the experiments 
shows, however, that this cannot be right. 

Suppose we reduce 
the output of the electron gun 
to one particle each minute. 

The Airy pattern is gone, 
and all we see 
is a small flash every minute. 

Let's leave this set-up to run for a while, 
recording each small flash as it occurs. 

Afterwards, we map the locations 
of all the thousands of flashes.

Surprisingly, we do not end up 
with a random arrangement of dots, 
but with the Airy pattern again. 

This result is extremely strange. 

No individual electron 
can know where all the earlier 
and later electrons are going to hit, 
so they cannot communicate 
with each other to create the bullseye pattern. 

Rather, each electron 
must have travelled 
like a wave through the hole 
to produce the characteristic pattern, 
then changed back into a particle 
to produce the point on the screen. 

This, of course, is the famous 
wave-particle duality of quantum mechanics.

This strange behaviour is shared 
by any sufficiently small piece of matter, 
including electrons, neutrons, photons 
and other elementary particles, but not just by these. 

Similar effects have been observed 
for objects that are large enough in principle 
to be seen under a microscope, such as buckyballs.

In order to explain the peculiar behaviour of such objects, 
physicists associate a wave function with each of them. 

Despite the fact that these waves 
have the usual properties of more familiar waves 
such as sound or water waves, including amplitude 
(how far up or down it deviates from the rest state), 
phase (at what point in a cycle the wave is), 
and interference (so that "up" and "down" phases 
of waves meeting each other cancel out), 
what they are waves in is not at all transparent. 

Einstein aptly spoke of a "phantom field" as their medium.

For a wave in an ordinary medium such as water, 
we can calculate its energy at any one point 
by taking the square of its amplitude. 

Wave functions, however, carry no energy. 

Instead, the square of their amplitude 
at any given point gives us the probability 
of observing the particle if a detector 
such as the phosphor-coated screen is placed there.

Clearly, the point where an object switches 
from being a probability wave, 
with its potential existence smeared out across space, 
and becomes an actual, spatially localised object 
is crucially important to understanding whether matter is real. 

What exactly happens when the wave function collapses 
- when among the countless possibilities where the particle 
could be at any moment, one is chosen, while all the others are rejected?

First of all, we have to ask ourselves 
when this choice is made. 

In the example described above, 
it seems to happen just before 
the flash on the phosphor screen. 

At this moment, 
a measurement of the electron's position 
was made by a piece of phosphor 
glowing as the particle struck it, 
so there must have been an electron there, 
and not just a probability wave.

But assume we cannot be 
in the lab to observe the experiment, 
so we point a camera at the phosphor screen 
and have the result sent via a satellite link 
to a computer on our desktop. 

In this case, the flash of light 
emitted from the phosphor screen 
has to travel to the camera recording it, 
and the process is repeated: like the electrons, 
light also travels as a wave and arrives as a particle. 

What reason is there to believe 
that the switch from probability wave 
to particle actually occurred 
on the phosphor screen, and not in the camera?

At first, it seemed as if the phosphor screen 
was the measuring instrument, 
and the electron was the thing being measured. 

But now the measuring device is the camera 
and the phosphor screen is part of what is measured. 

Given that any physical object 
transmitting the measurement 
we can add on to this sequence 
- the camera, the computer, 
our eyes, our brain 
- is made up of particles 
with the same properties as the electron, 
how can we determine any particular step 
at which to place the cut between 
what is measured and what is doing the measuring?

This ever-expanding chain 
is called the von Neumann chain, 
after the physicist and mathematician John von Neumann. 

One of his Princeton University colleagues, 
Eugene Wigner, made a suggestion 
as to where to make the cut. 

As we follow the von Neumann chain upwards, 
the first entity we encounter that is not made up 
in any straightforward fashion out of pieces of matter 
is the consciousness of the observer. 

We might therefore want to say 
that when consciousness enters the picture, 
the wave function collapses 
and the probability wave turns into a particle.

The idea that consciousness 
brings everyday reality into existence 
is, of course, deeply strange; perhaps 
it is little wonder that it is a minority viewpoint.

There is another way of interpreting 
the measurement problem 
that does not involve consciousness 
- though it has peculiar ramifications of its own. 

But for now let's explore 
Wigner's idea in more depth.

If a conscious observer 
does not collapse the wave function, 
curious consequences follow. 

As more and more objects 
get sucked into the vortex 
of von Neumann's chain 
by changing from being 
a measuring instrument 
to being part of what is measured, 
the "spread-out" structure 
of the probability wave 
becomes a property of these objects too. 

The "superposed" nature of the electron 
- its ability to be at various places at once - 
now also affects the measuring instruments.

It has been verified experimentally 
that not just the unobservably small, 
but objects large enough 
to be seen under a microscope, 
such as a 60-micrometre-long metal strip, 
can exhibit such superposition behaviour. 

Of course, we can't look through a microscope 
and see the metal strip being at two places at once, 
as this would immediately collapse the wave function. 

Yet it is clear that the indeterminacy 
we found at the atomic level 
can spread to the macro level.

Yet if we accept that the wave function must collapse 
as soon as consciousness enters the measurement, 
the consequences are even more curious. 

If we decide to break off the chain at this point, 
it follows that, according to one of our definitions 
of reality, matter cannot be regarded as real. 

If consciousness is required 
to turn ghostly probability waves 
into things that are more or less 
like the objects we meet in everyday life, 
how can we say that matter 
is what would be there anyway, 
whether or not human minds were around?

But perhaps this is a bit too hasty. 

Even if we agree with the idea 
that consciousness is required to break the chain, 
all that follows is that the dynamic attributes 
of matter such as position, momentum 
and spin orientation are mind-dependent. 

It does not follow that its static attributes, 
including mass and charge, are dependent on in this. 

The static attributes are there whether we look or not.

Nevertheless, we have to ask ourselves 
whether redefining matter 
as "a set of static attributes" 
preserves enough of its content 
to allow us to regard matter as real. 

In a world without minds, 
there would still be attributes 
such as mass and charge, 
but things would not be 
at any particular location 
or travel in any particular direction. 

Such a world has virtually 
nothing in common 
with the world as it appears to us. 

Werner Heisenberg observed that: 
"the ontology of materialism 
rested upon the illusion 
that the kind of existence, 
the direct 'actuality' of the world around us, 
can be extrapolated into the atomic range. 

This extrapolation, however, 
is impossible... Atoms are not things."

It seems that the best 
we are going to get at this point 
is the claim that some things 
are there independent of whether we, 
as human observers, are there, 
even though they 
might have very little to do 
with our ordinary understanding of matter.

Does our understanding 
of the reality of matter 
change if we choose 
the other strong definition of reality 
- not by what is there anyway, 
but by what provides 
the foundation for everything else 
(see "Reality: The definition")?

In order to answer this question, 
we have to look at the key 
scientific notion of a reductive explanation. 

Much of the power of scientific theories 
derives from the insight that we can 
use a theory that applies to a certain set 
of objects to explain the behaviour 
of a quite different set of objects. 

We therefore don't need 
a separate set of laws and principles 
to explain the second set.

A good example 
is the way in which theories 
from physics and chemistry, 
dealing with inanimate matter, 
can be used to explain biological processes. 

There is no need to postulate 
a special physics or a special chemistry 
to explain an organism's metabolism, 
how it procreates, how its genetic information 
is passed on, or how it ages and dies. 

The behaviour of the cells 
that make up the organism 
can be accounted for 
in terms of the nucleus, 
mitochondria and other subcellular entities, 
which can in turn be explained in terms 
of chemical reactions 
based on the behaviour of molecules 
and the atoms that compose them. 

For this reason, 
explanations of biological processes 
can be said to be reducible 
to chemical and ultimately to physical ones.

If we pursue a reductive explanation 
for the phenomena around us, 
a first step is to reduce statements 
about the medium-sized goods that surround us 
- bricks, brains, bees, bills and bacteria -
to statements about fundamental material objects, 
such as molecules. 

We then realise 
everything about these things 
can be explained in terms 
of their constituents, namely their atoms. 

Atoms, of course, 
have parts as well, 
and we are now well on our way 
through the realm 
of ever smaller subatomic particles, 
perhaps (if string theory is correct) 
all the way down 
to vibrating strings of pure energy. 

So far we have not reached 
the most fundamental objects. 

In fact, there is not even an agreement 
that there are any such objects.

Yet this is no reason to stop 
our reductionist explanation here, 
since we can always understand 
the most basic physical objects 
in terms of where they are in space and time. 

Instead of talking about a certain particle 
that exists at such-and-such a place 
for such-and-such a period of time, 
we can simply reduce this 
to talk about a certain region in space 
that is occupied between two different times.

We can go even more fundamental. 

If we take an arbitrary fixed point in space, 
and a stable unit of spatial distance, 
we can specify any other point 
in space by three coordinates. 

These simply tell us 
to go so many units up or down, 
so many units left or right, 
and so many units back or forth. 

We can do the same with points in time. 

We now have a way 
of expressing points in space-time 
as sets of four numbers, x, y, z and t, 
where x, y, and z represent 
the three spatial dimensions 
and t the time dimension. 

In this way, reality 
can be boiled down to numbers.

And this opens the door 
to something yet more fundamental. 

Mathematicians have found 
a way of reducing numbers 
to something even more basic: sets. 

To do this, they replace 
the number 0 with the empty set, 
the number 1 with the set 
that contains just the empty set, and so on 
(see "Reality: Is everything made of numbers?"). 

All the properties of numbers 
also hold for all these ersatz numbers 
made from sets. 

It seems as if we have now reduced 
all of the material world around us to an array of sets.

For this reason, it is important to know 
what these mathematical objects called sets really are. 

There are two views 
of mathematical objects 
that are important in this context. 

First, there is the view 
of them as "Platonic" objects. 

This means that mathematical objects 
are unlike all other objects we encounter. 

They are not made of matter, 
they do not exist in space or time, 
do not change, cannot be created or destroyed, 
and could not have failed to exist. 

According to the Platonic understanding, 
mathematical objects exist in a "third realm", 
distinct from the world of matter, on the one hand, 
and the world of mental entities, such as 
perceptions, thoughts and feelings, on the other.

Second, we can 
understand mathematical objects 
as fundamentally mental in nature. 

They are of the same kind as the other things 
that pass through our mind: 
thoughts and plans, concepts and ideas. 

They are not wholly subjective; 
other people can have 
the very same mathematical object 
in their minds as we have in ours, 
so that when we both talk 
about the Pythagorean theorem, 
we are talking about the same thing. 

Still, they do not exist 
except in the minds in which they occur.

Either of these understandings leads to a curious result. 

If the bottom level of the world consists of sets, 
and if sets are not material 
but are instead some Platonic entities, 
material objects have completely disappeared 
from view and cannot be real in the sense 
of constituting a fundamental basis of all existence. 

If we follow scientific reductionism all the way down, 
we end up with stuff that certainly 
does not look like tiny pebbles or billiard balls, 
not even like strings vibrating in a multidimensional space, 
but more like what pure mathematics deals with.

Of course, the Platonistic view of mathematical objects 
is hardly uncontroversial, and many people 
find it hard to get any clear idea of how objects 
could exist outside of space and time. 

But if we take mathematical objects 
to be mental in nature, 
we end up with an even stranger scenario.

The scientific reductionist sets out 
to reduce the human mind 
to the activity of the brain, 
the brain to an assembly of interacting cells, 
the cells to molecules, the molecules to atoms, 
the atoms to subatomic particles, 
the subatomic particles 
to collections of space-time points, 
the collections of space-time points 
to sets of numbers, 
and the sets of numbers to pure sets. 

But at the very end of this reduction, 
we now seem to loop right back 
to where we came from: to the mental entities.

We encounter a similar curious loop 
in the most influential way 
of understanding quantum mechanics, 
the Copenhagen interpretation. 

Unlike Wigner's consciousness-based interpretation, 
this does not assume the wave function collapses 
when a conscious mind observes the outcome of some experiment. 

Instead, it happens when the system to be measured 
(the electron) interacts with the measuring device (the phosphor screen). 

For this reason, it has to be assumed 
that the phosphor screen 
will not itself exhibit 
the peculiar quantum behaviour 
shown by the electron.

In the Copenhagen interpretation, then, 
things and processes describable 
in terms of familiar classical concepts 
are the foundation of any physical interpretation. 

And this is where the circularity comes in. 

We analyse the everyday world 
of medium-sized material things 
in terms of smaller and smaller constituents 
until we deal with parts that are so small 
that quantum effects become relevant for describing them. 

But when it comes to spelling out 
what is really going on 
when a wave function collapses 
into an electron hitting a phosphor screen, 
we don't ground our explanation 
in some yet more minute micro-level structures; 
we ground it in terms of readings 
made by non-quantum material things.

What this means 
is that instead of going further down, 
we instead jump right back up to the level 
of concrete phenomena of sensory perception, 
namely measuring devices 
such as phosphor screens and cameras. 

Once more, we are in a situation 
where we cannot say that the world 
of quantum objects is fundamental. 

Nor can we say that the world of measuring devices 
is fundamental since these devices are themselves 
nothing but large conglomerations of quantum objects.

We therefore have a circle of things 
depending on each other, even though, 
unlike in the previous case, 
mental objects are no longer part of this circle. 

As a result, neither the phosphor screen 
nor the minute electron can be regarded as real 
in any fundamental sense, since neither 
constitutes a class of objects 
that everything depends on. 

What we thought 
we should take to be
the most fundamental turns out 
to involve essentially what 
we regarded as the least fundamental.

In our search for foundations, 
we have gone round in a circle, from the mind, 
via various components of matter, back to the mind - 
or, in the case of the Copenhagen interpretation, 
from the macroscopic to the microscopic, 
and then back to the macroscopic. 

But this just means that nothing is fundamental, 
in the same way there is no first or last stop 
on London Underground's Circle Line. 

The moral to draw from the reductionist scenario 
seems to be that either what is fundamental 
is not material, or that nothing at all is fundamental.

__________________________________________________

Jan Westerhoff is a philosopher at the University of Durham 
and the University of London's School of Oriental and African Studies, 
both in the UK, and author of 
Reality: A very short introduction (Oxford University Press, 2011)


• MATHEMATICS

Reality: Is everything made of numbers?
New Scientist  26 September 2012 by Amanda Gefter
Magazine issue 2884


Dig deep enough into the fabric of reality 
and you eventually hit a seam of pure mathematics

When Albert Einstein finally completed 
his general theory of relativity in 1916, 
he looked down at the equations 
and discovered an unexpected message: 
the universe is expanding.

Einstein didn't believe 
the physical universe could shrink or grow, 
so he ignored what the equations were telling him. 

Thirteen years later, Edwin Hubble 
found clear evidence of the universe's expansion. 
Einstein had missed the opportunity to make 
the most dramatic scientific prediction in history.

How did Einstein's equations 
"know" that the universe 
was expanding when he did not? 

If mathematics 
is nothing more than a language 
we use to describe the world, 
an invention of the human brain, 
how can it possibly churn out 
anything beyond what we put in? 

"It is difficult to avoid the impression 
that a miracle confronts us here," 
wrote physicist Eugene Wigner 
in his classic 1960 paper 
"The unreasonable effectiveness 
of mathematics in the natural sciences"
(Communications on Pure 
and Applied Mathematics, vol 13, p 1).

The prescience of mathematics 
seems no less miraculous today. 

At the Large Hadron Collider at CERN, 
near Geneva, Switzerland, physicists recently 
observed the fingerprints of a particle 
that was arguably discovered 48 years ago 
lurking in the equations of particle physics.

How is it possible that mathematics 
"knows" about Higgs particles 
or any other feature of physical reality? 

"Maybe it's because math is reality," 
says physicist Brian Greene 
of Columbia University, New York. 

Perhaps if we dig deep enough, 
we would find that physical objects 
like tables and chairs are ultimately 
not made of particles or strings, but of numbers.

"These are very difficult issues," 
says philosopher of science James Ladyman 
of the University of Bristol, UK, 
"but it might be less misleading 
to say that the universe is made 
of maths than to say it is made of matter."

Difficult indeed. 

What does it mean 
to say that the universe 
is "made of mathematics"? 

An obvious starting point 
is to ask what mathematics is made of. 

The late physicist John Wheeler 
said that the "basis of all mathematics is 0 = 0". 

All mathematical structures 
can be derived from something 
called "the empty set", 
the set that contains no elements. 

Say this set corresponds to zero; 
you can then define the number 1 
as the set that contains only the empty set, 
2 as the set containing the sets 
corresponding to 0 and 1, and so on. 

Keep nesting the nothingness 
like invisible Russian dolls 
and eventually all of mathematics appears. 

Mathematician Ian Stewart 
of the University of Warwick, UK, 
calls this "the dreadful secret of mathematics: 
it's all based on nothing" 
(New Scientist, 19 November 2011, p 44). 

Reality may come down to mathematics, 
but mathematics comes down to nothing at all.

That may be the ultimate clue to existence 
- after all, a universe made of nothing 
doesn't require an explanation. 

Indeed, mathematical structures 
don't seem to require a physical origin at all. 

"A dodecahedron was never created," 
says Max Tegmark of the 
Massachusetts Institute of Technology. 

"To be created, something first 
has to not exist in space or time and then exist." 

A dodecahedron doesn't exist 
in space or time at all, he says 
- it exists independently of them. 

"Space and time themselves 
are contained within 
larger mathematical structures," he adds.

These structures just exist; 
they can't be created or destroyed.

That raises a big question: 
why is the universe only made 
of some of the available mathematics? 

"There's a lot of math out there," Greene says. 

"Today only a tiny sliver of 
it has a realisation in the physical world. 

Pull any math book off the shelf 
and most of the equations in it 
don't correspond to any 
physical object or physical process."

It is true that seemingly arcane 
and unphysical mathematics 
does, sometimes, turn out 
to correspond to the real world. 

Imaginary numbers, for instance, 
were once considered 
totally deserving of their name, 
but are now used to describe 
the behaviour of elementary particles; 
non-Euclidean geometry 
eventually showed up as gravity. 

Even so, these phenomena 
represent a tiny slice 
of all the mathematics out there.

Not so fast, says Tegmark. 

"I believe that physical existence 
and mathematical existence are the same, 
so any structure that exists mathematically 
is also real," he says.

So what about the mathematics 
our universe doesn't use? 

"Other mathematical structures 
correspond to other universes," Tegmark says. 

He calls this the "level 4 multiverse", 
and it is far stranger than the multiverses 
that cosmologists often discuss. 

Their common-or-garden multiverses 
are governed by the same basic 
mathematical rules as our universe, 
but Tegmark's level 4 multiverse 
operates with completely different mathematics.

All of this sounds bizarre, 
but the hypothesis that physical reality 
is fundamentally mathematical has passed every test. 

"If physics hits a roadblock 
at which point it turns out 
that it's impossible to proceed, 
we might find that nature 
can't be captured mathematically," Tegmark says. 

"But it's really remarkable 
that that hasn't happened. 

Galileo said that the book of nature 
was written in the language of mathematics 
- and that was 400 years ago."

If reality isn't, at bottom, 
mathematics, what is it? 

"Maybe someday 
we'll encounter an alien civilisation 
and we'll show them 
what we've discovered 
about the universe," Greene says. 

"They'll say, 'Ah, math. We tried that. 
It only takes you so far. Here's the real thing.' 

What would that be? 
It's hard to imagine. 

Our understanding 
of fundamental reality 
is at an early stage."

______________

Amanda Gefter is a writer 
and New Scientist consultant 
based in Boston, Massachusetts

• INFORMATION THEORY

Reality: A universe of information
New Scientist  26 September 2012 
by Michael Brooks
Magazine issue 2884. 

What we call reality might actually be the output 
of a program running on a cosmos-sized quantum computer

Whatever kind of reality you think 
you're living in, you're probably wrong. 

The universe is a computer, 
and everything that goes on in it 
can be explained 
in terms of information processing.

The connection 
between reality and computing 
may not be immediately obvious, 
but strip away the layers 
and that is exactly 
what some researchers think we find. 

We think of the world 
as made up of particles 
held together by forces, for instance, 
but quantum theory tells us that t
hese are just a mess of fields 
we can only properly describe 
by invoking the mathematics of quantum physics.

That's where the computer comes in, 
at least if you think of it in conceptual terms 
as something that processes information 
rather than as a boxy machine on your desk. 

"Quantum physics is almost phrased 
in terms of information processing," 
says Vlatko Vedral of the University of Oxford. 

"It's suggestive that you will find 
information processing at the root of everything."

Information certainly has a special place in quantum theory. 

The famous uncertainty principle 
- which states that you can't simultaneously 
know the momentum and position of a particle - 
comes down to information. 

As does entanglement, 
where quantum objects 
share properties and exchange information 
irrespective of the physical distance between them.

In fact, every process in the universe 
can be reduced to interactions 
between particles that produce binary answers: 
yes or no, here or there, up or down. 

That means nature, 
at its most fundamental level, 
is simply the flipping of binary digits 
or bits, just like a computer. 

The result of the myriad bit flips 
is manifest in what we perceive 
as the ongoing arrangement, 
rearrangement and interaction of atoms 
- in other words, reality.

According to Ed Fredkin 
of the Massachusetts Institute of Technology, 
if we could dig into this process 
we would find that the universe 
follows just one law, 
a single information-processing rule 
that is all you need to build a cosmos. 

In Fredkin's view, 
this would be some form 
of "if - then" procedure; 
the kind of rule used 
in traditional computing 
to manipulate the bits 
held by transistors on a chip 
and operate the logic gates, 
but this time applied 
to the bits of the universe.

Vedral and others think 
it's a little more complex than that. 

Because we can reduce everything in the universe 
to entities that follow the laws of quantum physics, 
the universe must be a quantum computer 
rather than the classical type we are familiar with.

One of the attractions of this idea 
is that it can supply an answer to the question 
"why is there something rather than nothing?". 

The randomness inherent 
in quantum mechanics 
means that quantum information 
- and by extension, a universe - 
can spontaneously come into being, Vedral says.

For all these theoretical ideas, 
proving that the universe 
is a quantum computer is a difficult task. 

Even so, there is one observation 
that supports the idea that the universe 
is fundamentally composed of information. 

In 2008, the GEO 600 gravitational wave detector 
in Hannover, Germany, picked up an anomalous 
signal suggesting that space-time is pixellated. 

This is exactly what would be expected 
in a "holographic" universe, 
where 3D reality is actually a projection 
of information encoded 
on the two-dimensional surface 
of the boundary of the universe 
(New Scientist, 17 January 2009, p 24).

This bizarre idea arose 
from an argument over black holes. 

One of the fundamental tenets of physics 
is that information cannot be destroyed, 
but a black hole appears to violate this 
by swallowing things that contain information 
then gradually evaporating away. 

What happens to that information 
was the subject of a long debate 
between Stephen Hawking 
and several of his peers. 

In the end, Hawking lost the debate, 
conceding that the information 
is imprinted on the event horizon 
that defines the black hole's boundary 
and escapes as the black hole evaporates. 

This led theoretical physicists 
Leonard Susskind and Gerard't Hooft 
to propose that the entire universe 
could also hold information at its boundary 
- with the consequence that our reality 
could be the projection of that information 
into the space within the boundary. 

If this conjecture is true, reality 
is like the image of Princess Leia 
projected by R2D2 in Star Wars: a hologram.

________________________
Michael Brooks is a writer 
and New Scientist consultant based in Sussex, UK


• CONSCIOUSNESS

Reality: How does consciousness fit in?
New Scientist  26 September 2012 by Michael Brooks
Magazine issue 2884. 

Some theories hold that reality 
and consciousness are one and the same. 

Is the universe really all inside your head

Descartes might 
have been onto something 
with "I think therefore I am", 
but surely "I think therefore you are" 
is going a bit far? 

Not for some
of the brightest minds 
of 20th-century physics 
as they wrestled mightily 
with the strange implications 
of the quantum world.

According to prevailing wisdom, 
a quantum particle 
such as an electron or photon 
can only be properly described 
as a mathematical entity 
known as a wave function. 

Wave functions can exist 
as "superpositions" 
of many states at once. 

A photon, for instance, 
can circulate in two different directions 
around an optical fibre; 
or an electron can simultaneously 
spin clockwise and anticlockwise 
or be in two positions at once.

When any attempt is made to observe 
these simultaneous existences, however, 
something odd happens: we see only one. 

How do many possibilities become one physical reality?

This is the central question in quantum mechanics, 
and has spawned a plethora of proposals, or interpretations. 

The most popular is the Copenhagen interpretation, 
which says nothing is real until it is observed, or measured. 

Observing a wave function causes the superposition to collapse.

However, Copenhagen says nothing 
about what exactly constitutes an observation. 

John von Neumann broke this silence 
and suggested that observation 
is the action of a conscious mind. 

It's an idea also put forward by Max Planck, 
the founder of quantum theory, who said in 1931, 
"I regard consciousness as fundamental.
I regard matter as derivative from consciousness."

That argument relies on the view 
that there is something 
special about consciousness, 
especially human consciousness. 

Von Neumann argued that everything in the universe 
that is subject to the laws of quantum physics 
creates one vast quantum superposition. 

But the conscious mind is somehow different. 

It is thus able to select out 
one of the quantum possibilities on offer, 
making it real - to that mind, at least.

Henry Stapp of the Lawrence 
Berkeley National Laboratory in California 
is one of the few physicists that still subscribe to this notion: 
we are "participating observers" whose minds 
cause the collapse of superpositions, he says. 

Before human consciousness appeared, 
there existed a multiverse of potential universes, Stapp says. 

The emergence of a conscious mind 
in one of these potential universes, ours, 
gives it a special status: reality.

There are many objectors. 

One problem is that 
many of the phenomena 
involved are poorly understood. 

"There's a big question in philosophy 
about whether consciousness actually exists," 
says Matthew Donald, a philosopher 
of physics at the University of Cambridge. 

"When you add on quantum mechanics it all gets a bit confused."

Donald prefers an interpretation 
that is arguably even more bizarre: "many minds". 

This idea - related to the "many worlds" 
interpretation of quantum theory, 
which has each outcome of a quantum decision 
happen in a different universe - 
argues that an individual 
observing a quantum system 
sees all the many states, 
but each in a different mind. 

These minds all arise 
from the physical substance of the brain, 
and share a past and a future, 
but cannot communicate 
with each other about the present.

Though it sounds hard to swallow, 
this and other approaches 
to understanding the role of the mind 
in our perception of reality 
are all worthy of attention, Donald reckons. 

"I take them very seriously," he says.

___________________

Michael Brooks is a consultant for New Scientist, 
and author of The Secret Anarchy of Science (Profile/Overlook)


• EPISTEMOLOGY
Reality: How can we know it exists?
New Scientist 01 October 2012 by Mike Holderness
Magazine issue 2884.

Proving whether or not reality 
is an illusion is surprisingly difficult

Philophers are not being rude 
when they describe the approach 
most of us take as naive realism. 

After all, when they cross the street 
on the way to work, 
they tend to accept implicitly 
- as we all do - that there is 
an external reality that exists 
independently of our observations of it. 

But at work, they have to ask: 
if there is, how can we know?

In other words, 
the question "what exists?" reduces, 
for what in philosophy 
passes for practical purposes, 
to questions such as 
"what do we mean by 'know'?"

Plato had a go at it 
2400 years ago, 
defining "knowledge" 
as "justified true belief". 

But testing the justification 
or the truth of beliefs 
traces back to our perceptions, 
and we know these can deceive us.

Two millennia later, 
René Descartes decided to work out 
what he was sure he knew. 

Legend has it that he climbed 
into a large stove to do so 
in warmth and solitude. 

He emerged declaring 
that the only thing he knew 
was that there was something 
that was doubting everything.

The logical conclusion 
of Descartes's doubt is solipsism, 
the conviction that one's 
own consciousness is all there is. 

It's an idea that is difficult to refute.

Samuel Johnson's notoriously bluff riposte 
to the questioning of the reality of objects 
- "I refute it thus!", kicking a stone - 
holds no philosophical water. 

As Descartes pointed out a century earlier, 
it is impossible to know we are not dreaming.

Nor has anyone 
had much luck making sense of dualism 
- the idea that mind and matter are distinct. 

One response is that there is only matter, 
making the mind an illusion 
that arises from neurons doing their thing. 

The opposite position is "panpsychism", 
which attributes mental properties to all matter. 

As the astrophysicist Arthur Eddington 
expressed it in 1928: 
"the stuff of the world is mind-stuff... 
not altogether foreign 
to the feelings in our consciousness".

Quite separately, rigorous logicians 
such as Harvard's Willard Van Orman Quine 
abandoned the search for a foundation of reality
 and took "coherentist" positions. 

Let go of the notion 
of a pyramid of knowledge, 
they argued: think instead 
of a raft built out of our beliefs, 
a seaweedy web 
of statements about perceptions 
and statements about statements, 
not "grounded" in anything 
but hanging together 
and solid enough to set sail upon. 

Or even, possibly, to be a universe.

This idea is circular, and it's cheating, 
say critics of a more foundationist bent. 

It leads back to the suspicion 
that there actually is no reality 
independent of our observations. 

But if there is - how can we know?

_______________________

Mike Holderness is a writer based in London


• SIMULATION

Reality: The future
New Scientist 01 October 2012 by Richard Webb
Magazine issue 2884.

It’s possible 







+we live in fundamental reality. 
Future beings almost certainly won't

Before cursing the indolence of today's youth, 
absorbed in the ever-more intricate virtual realities 
of video games rather than scrumping 
the ripe fruits of real reality outside, consider this. 

Perhaps they are actually 
immersing themselves in our future 
- or even our present.

The story of our recent technological development 
has been one of ever-increasing computational power. 

At some future time we are unlikely 
to be content with constructing 
tightly circumscribed game worlds. 

We will surely begin to simulate everything, 
including the evolutionary history that led to where we are.

Flicking the switch on such a world simulation 
could have fundamental ramifications 
for our concept of reality, 
according to philosopher Nick Bostrom 
of the University of Oxford. 

If we can do it, that makes 
it likely it has been done before. 

In fact, given the amount 
of computing power 
advanced civilisations 
are likely to have at their fingertips, 
it will probably have been done 
a vast number of times.

So switching on our own simulation 
will tell us that we are almost undoubtedly 
in someone else's already. 

"We would have to think 
we are one of the simulated people, 
rather than one of the rare, 
exceptional non-simulated people," says Bostrom.

Probably, anyway. 

There has to be a basement level 
of reality somewhere, in which 
the "master" simulation exists. 

It is possible that we live in that reality. 

Depending on its laws of physics, 
the basement's computing resources 
are likely to be finite. 

And those resources must support 
not only the master simulation, 
but any simulations people 
in that simulation decide to create 
- perhaps limiting their number, 
and thus increasing 
the chances that ours is the base reality.

Either way, 
our ability to check our own status, 
and that of the fundamental 
physical laws we discover, is limited. 

If we are in the basement, 
we have nowhere to drill down to, 
and if we aren't, whether we can 
depends on the rules put in place 
by those who built the simulation. 

So even if we do end up constructing 
what could be reality for someone else, 
we'll probably never know for sure 
where we ourselves stand. 

Who's to say video games are the lesser reality?

_____________________

Richard Webb 
is a New Scientist feature editor

No hay comentarios:

Publicar un comentario

COMENTE SIN RESTRICCIONES PERO ATÉNGASE A SUS CONSECUENCIAS