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Is space created ?
Reflections on Śaṅkara’s philosophy and philosophy of physics
J. DUQUETTE
K. RAMASUBRAMANIAN
1. Introduction
From Antiquity to the present days, the concept of space has engaged the attention of
philosophers and scientists of every civilization. Space as a subject of philosophical enquiry
appears quite early in Greek philosophy, especially in the works of natural philosophers such
as Philolaus, Plato and Aristotle.1 For thousands of years, Aristotle’s philosophy constituted the framework from which successive generations of Western philosophers and scientists
used to reason about space. This view was however shaken with the publication of Newton’s
Principia in 1687. In this monumental work, Newton establishes the concept of absolute
space as an entity distinct and separate from material bodies, homogeneous, immobile and
causally inert. Until the advent of Einstein’s theory of relativity (1905-1915), this concept
reigned supreme in classical physics. But with Einstein’s theory, a novative way of reflecting
upon the notions of space, time and gravitation was proposed. The worldview set forth in
this theory did not only give rise to a whole new paradigm in the field of theoretical physics,
beyond what Newton had himself achieved with his theory, but it had a strong and vivifying
impact in philosophy of science also.2 Nowadays, notwithstanding the various advances in
physics per se, philosophers of physics are struggling to come out with an understanding of
space that is in agreement with relativity as well as with the new requirements of quantum
physics. As there is no common theoretical framework yet linking these two theories, there
is no final agreement among physicists and philosophers as to the nature of space.
In India, the concept of space has also been subject to a deep philosophical enquiry. In
ancient Vedic texts, in particular the R
. gveda, it is more or less associated with the idea of
a primeval openness in which the world extends and manifests itself.3 In later Brāhman.as,
Āran.yakas and Upanis.ads, the emphasis is laid on the nature of ākāśa, which emerges as a
central concept especially in Upanis.adic cosmology. In these texts, ākāśa is endowed with
a rich variety of meanings. In some passages, it is considered as one of the five “elements”
(mahābhūtas), connected with hearing and sound ; at other places, it is conceived as the
space containing all bodies, or a subtle form of materiality ; elsewhere, it is approximated,
or even equated to the eternal Brahman, the creator and Being underlying the world. In
more or less the same way, this semantic ambiguity is also reflected in the later classical
systems of Indian philosophy (darśanas). In literature, we find a good deal of discussions
and debates on the concept of ākāśa, involving philosophers from Nyāya-Vaiśes.ika, Sām
. khya
and Vedānta schools of thought, as well as Buddhist and Jainist philosophers. The topics
examined vary from the ontological status of ākāśa to its role in the transmission of sound,
or in the creation and manifestation of the world. Of course, each school emphasized a
particular aspect of ākāśa in consonance with its own outlook at the world. In the Indian
context also, philosophers were facing the difficulty of defining with certainty the nature of
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space.
It is the recognition of such a fact, namely that there is no fundamental and definite answer
as regards space both in modern philosophy of physics and Indian philosophy, that led to
the present paper. It is indeed interesting, and certainly enriching, to compare how both
these traditions look differently upon the concept, and deal with its many facets. In the
process, we may also realize that both traditions are faced with the same questions when
trying to evolve a clear picture regarding the nature and origin of space. In literature, we
find only few comparative studies focusing upon this concept from the viewpoint of Indian
philosophy and physics.5 But as far as our knowledge goes, there exists no comparative
study taking into account both the standpoint of Indian philosophy and philosophy of physics per se. It is our aim in this short paper to provide the reader with few reflections on
the subject by taking resource from both these disciplines. The question tackled here is
one that was of deep interest for classical Indian philosophers and is still debated today :
Is space created ? For the sake of simplicity, we have decided to restrict our attention to a
particular adhikaran.a in Śaṅkara’s Brahmasūtrabhās.ya, the viyādhikaran.a (BSB II.3.1-7),
wherein the origin of ākāśa is questioned and discussed. This short analysis will be preceded
by a brief summary of the views adopted in Vaiśes.ika and Sām
. khya. We conclude this paper with few reflections on the concept of space in the light of modern philosophy of physics.
2. The nature of ākāśa in Vaiśes.ika and Sām
. khya
Together with Sām
. khya, the school of Vaiśes.ika probably offers the most significant philosophical explanation of ākāśa as a physical element. Both of these systems provide an
elaborate cosmological model, wherein a list of world constituents is given together with
an explanation of their arrangement. But while Vaiśes.ika divides the world synchronically
in terms of definite and distinct “categories” (padārthas) of reality, Sām
. khya depicts the
world in evolutive terms, as successive stages of evolution of prakr.ti, the primary principle
of materiality. In the former system, six basic padārthas are accepted, which are considered
to provide a complete inventory of the kinds of things that one finds in the world : substance
(dravya), quality (gun.a), action (karma), universal (sāmānya), particularity (viśes.a) and
inherence (samavāya).6 Despite its pluralistic outlook at the world, this school also accepts
certain structures of dependence and subordination between categories, such as inherence
and conjunction (sam
. yoga). As to Sām
. khya, it traces the whole physical world to a single
source (prakr.ti ) rather than to a set of distinct categories. It admits that twenty-three
evolutes (vikr.ti ) emerged from prakr.ti at the time of creation, in the following order :
non-individualized intellect (buddhi ), individuality (aham
. kāra), mind (manas), five organs
of perception (jñānendriyas), five organs of action (karmendriyas), five subtle elements
(tanmātras) and five gross elements (mahābhūtas). Pure consciousness (purus.a), for the
sake of whom evolution takes place, stands apart from the empirical world.
In Vaiśes.ika, the philosophical reasoning about ākāśa is governed by the substance-quality
paradigm. The following list of substances is accepted by Vaiśes.ika philosophers : five
elements (ākāśa, air, fire, water, earth), direction (diś), time (kāla), mental organs (manas) and selves (ātman). As substances, each element is endowed with one specific quality
(viśes.agun.a) and connected to a specific sense-organ.7 Like in the Upanis.ads, the corre2
lation between the five elements and the qualities perceived by sense-organs is accepted :
ākāśa is associated with sound only ; air with touch only ; fire with colour and touch ; water with taste, colour and touch ; earth with smell, taste, colour and touch. It is argued
by Praśastapāda and his commentators that among the substances, only ākāśa can be the
bearer of sound.8 No positive arguments are however given which explain how ākāśa, as
physical space per se, is qualitatively connected to sound. Thus, the function of ākāśa in
this system is mainly to afford a substantial basis for the phenomena of sound and hearing.
It is also worth noting that Vaiśes.ika introduces in its metaphysics two substances that
convey the idea of space, namely diś and ākāśa. The concept of diś is primarily associated
with the notion of direction, and thus serves as a spatial framework in which things and
phenomena are located with reference to each other. In contrast, ākāśa is something less
structured, without any internal structure or differentiation. It contains all things without
being affected by them in any way.9
An important feature of ākāśa, noteworthy in this context, is its non-atomic and eternal
(nitya) nature. Though it shares with air, fire, etc. the coordination with a specific quality (sound) and sense-organ (hearing), ākāśa does not consist of any parts and so cannot
form aggregates as other elements do. The other four elements are indeed composed of indivisible and indestructible atoms (paramān.us). Because they are composite, they are also
non-eternal. Unlike them, ākāśa is taken to be all-pervasive (vibhu), i.e. in contact with all
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substances of finite size (sarva-mūrta-dravya-sam
. yogitva). It is one and the same everywhere. From this property derives its eternality : having no parts and pervading everything,
it is not subject to change and decay. Space is thus eternal for Vaiśes.ikas, like atoms and
Īśvara, the creator of the world. The all-pervasiveness and eternality of ākāśa are also shared
by immaterial substances like diś and time. It has also some properties in common with the
self, namely the possession of specific qualities which last only for a single moment and exist
only in certain parts of the substance (ex : pleasure, pain, etc. in the case of the self and
sound in the case of ākāśa). The fact that ākāśa is envisaged as one of the five mahābhūtas
while being eternal and all-pervasive like immaterial substances, is peculiar to the Vaiśes.ika
conception of space.
In Sām
. khya, the ontological status of ākāśa is rather different. Though it also accepts a plurality of existents, such as five elements, atoms, selves, etc., like Vaiśes.ika, Sām
. khya admits
of only two eternal principles in its metaphysics : prakr.ti and purus.a. All evolutes of prakr.ti,
including ākāśa, have a finite existence and are ultimately resorbed into prakr.ti. Ākāśa is
neither created nor eternal : it is manifested through a gradual process of evolution emerging from prakr.ti. Precisely, the five elements emanate from the principle of individuality
(aham
. kāra), itself emerging from buddhi, the first evolute of prakr.ti. Among the elements,
ākāśa is the first element to be manifest, a characteristic that is also present in Upanis.ads
and Vedānta. An important feature of Sām
. khya cosmology is its distinction between two
phases in the development of elements : a generic and simple phase in which the elements
are not yet concretized and specified (tanmātras), and a specific phase where those subtle
elements combine together to form the five gross elements (mahābhūtas). In this system
also, ākāśa has sound (śabda) as its attribute, and so the subtle form of ākāśa is referred
to as śabdatanmātra, the non-specific essence of sound. In its gross form, ākāśa manifests
specific and perceptible sounds. The distinction between tanmātras and mahābhūtas is ho-
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wever problematic in Sām
. khya for there is no definite agreement in the basic texts as to the
exact relation between subtle and gross elements.11 The most common view is that each
successive subtle element combines with the previous one to produce its gross counterpart :
the subtle form of ākāśa (śabdatanmātra) generates the gross element ākāśa ; the subtle
form of air combines with śabdatanmātra to produce gross air, etc.
We find no indication in Sām
. khya of a non-elemental type of ākāśa like in Vaiśes.ika. Be12
cause it is atomic and non-eternal, it does not display any resemblance with either prakr.ti
or purus.a. Nonetheless, with the later contribution of Vijñānabhiks.u (16th century), ākāśa
comes closer to prakr.ti. It is maintained by him that there are two kinds of ākāśa : the usual
elemental ākāśa (kāryākāśa) - non-eternal and evolved from śabdatanmātra - and a causal
one (kāran.ākāśa), non-atomic and close to prakr.ti.13 The relation between kāran.ākāśa and
prakr.ti expresses itself through space (diś) and time (kāla), which manifest the inherent potentiality for change contained in prakr.ti.14 In his Sām
. khyapravacanabhās.ya (II.12), Vijñānabhiks.u maintains that eternal space and time are of the nature of kāran.ākāśa, and also allpervasive. As to empirical space and time, they are produced from the same ākāśa in terms
of its limiting adjuncts (upādhis).15 If prakr.ti consists in that which brings forth empirical
space and time to existence, we may understand kāran.ākāśa as that very potentiality itself.
Hence, phenomena are not taking place in space and time in this view ; empirical space
and time are themselves phenomena which depend upon a more fundamental entity, i.e. the
causal ākāśa.
3. Śaṅkara’s view of ākāśa : a discussion in BSB II.3.1-7
Like in other schools, the concept of ākāśa has also engaged the attention of Advaitins.
As far as Śaṅkara is concerned, we find short references to this concept in some of his
commentaries on Upanis.ads, as well as in few adhikaran.as in the Brahmasūtrabhās.ya. The
present adhikaran.a, called viyādhikaran.a (BSB II.3.1-7), is the most extensive one among
them. The main purport of it is to elucidate a possible doubt as regards the origin of ākāśa.
As a matter of fact, we find in the Upanis.ads two seemingly contradictory accounts for the
creation of elements :
He said, ‘O good looking one, by what logic can existence verily come out of nonexistence ? But surely, O good looking one, in the beginning all this was Existence
(sat), One only, without a second.’ That (Existence) say, ‘I shall become many. I shall
be born.’ That created fire. That fire saw, ‘I shall become many. I shall be born.’
That created water. [...] Those waters saw : ‘We shall become many, we shall be born
excellently.’ They created food [earth]. (ChU VI.2.2-4)
From that Brahman indeed, which is this Self, was produced space [ākāśa]. From space
emerged air. From air was born fire. From fire was created water. From water sprang
up earth. (TU II.1.1)
In the Chāndogya Upanis.ad (ChU), fire is said to be created first and succeeded by water
and earth whereas in the Taittirı̄ya (TU), fire comes in the third position while ākāśa and
air come before fire. If we agree with ChU, ākāśa not being mentioned, we may conclude
that it does not originate and is thus eternal. On the other hand, if we follow TU, ākāśa
must be considered as a created element. Thus, the śruti itself seems to diverge as to the
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origin of ākāśa. The present adhikaran.a carefully analyzes this question and tries to provide
a solution that is both in agreement with logical reasoning and śruti.
3.1 The statements are irreconcilable : the pūrvapaks.ı̄
In the first two sūtras (BSB II.3.1-2), the two different accounts of creation and their implication as to the origin of ākāśa are stated. The position taken by the pūrvapaks.ı̄ here is that
it is impossible to arrive at a final conclusion regarding the creation of elements because the
two theories of creation are fundamentally irreconcilable with each other. In all evidence, we
cannot claim that both fire and ākāśa have the primary position in the scheme of evolution.
We can neither conceive that they are created simultaneously since in TU fire is said to
be created only after ākāśa and air have been created. Moreover, in ChU fire is said to be
created from sat while it is created from air in TU. For all these reasons, both śrutis must be
considered as apramān.am, not valid means of knowledge as regards the creation of elements.
3.2 Space is eternal : the siddhānta ekadeśı̄
The next three sūtras (BSB II.3.3-5) try to maintain the validity of both śrutis by giving
a secondary meaning to TU and a primary meaning to ChU, thereby taking ākāśa as
having no origin. The proponent here, referred to as siddhānta ekadeśı̄, mainly resorts to
the Vaiśes.ika theory of causation to defend his point, and also to certain other statements
found in Upanis.ads as well in other scriptures. The arguments are here summarized :
1. According to Vaiśes.ika, the cause of an effect is of three types : inherent (samavāyi ), noninherent (asamavāyi ) and efficient (nimitta).16 In no case can such causes account for the
creation of ākāśa, the reasons being that : “an inherent cause of an object is constituted by
an abundance of substance of the same class. But for space [ākāśa] there can be no such
abundance of any substance of the same class, which can constitute its inherent cause ; nor is
there any conjunction of such substances which can be accepted as the non-inherent causes
from which space can emerge. And since these two causes are absent, any efficient cause for
space, which functions when these are favourable, becomes a far cry.”
2. When an entity is created, it is possible to conceive of a distinction before and after the time
of its creation. But this cannot be shown in the case of ākāśa, which can never be conceived
of “as existing without space, interstices, or cavities.”
3. Ākāśa cannot be created because it is different from other created elements, such as earth,
etc., for it is all-pervasive (vibhu), etc.
4. The śruti itself declares the eternality of ākāśa in passages such as “Now the subtle - it is
air and space. It is immortal” (BrU II.3.3), “It is all-pervasive and eternal like space” (no
reference available), “Brahman has space as Its body” (TU I.6.2), “Space is the Self” (TU
I.7.1), etc.
In the fifth sūtra, we find an interesting objection against this position. If we admit that
ākāśa, being eternal, is on a par with Brahman before creation, how one then accounts for
the śruti : “In the beginning...this [universe] was Being alone, one only without a second”
(ChU VI.2.1) ? Moreover, if ākāśa is not created, how can we justify the statement : “That
by knowing which all that...is not known [i.e. all that is created] becomes known” (ChU
VI.1.3) ? Here, the siddhānta ekadeśı̄ tries to show how both these śrutis remain meaningful
even if ākāśa is accepted to be present with Brahman before creation. He first notices that
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the expression “one only” should be understood with reference to the absence of effects of
Brahman, and not with reference to ākāśa, which is eternal.17 As to the expression “without
a second”, it implies that there is no other efficient cause than Brahman for creation. But
since ākāśa and Brahman possess the same characteristics, such as all-pervasiveness, partlessness, formlessness, etc., it is impossible to perceive them separately. Like milk and water
in a mixture, there is no way to distinguish them separately as two entities. Owing to this
fact, the śruti telling that Brahman is “one only without a second” remains meaningful.
For the same reason, the second śruti is respected : by knowing Brahman, which is nonseparate from ākāśa as water in milk, one comes to know everything including ākāśa itself.18
3.3 Space is created : the paramasiddhānta
In the last two sūtras (BSB II.3.6-7), these arguments are successively refuted by Śaṅkara,
the paramasiddhānta, who concludes that ākāśa must be considered as a created element. In
the first of these sūtras, Śaṅkara resorts to śruti to defend his position. It is maintained that
the real import of the statement “That by knowing which all that...is not known becomes
known”, is that all the things to be known must originate from Brahman. As an example,
only those things which are made of clay become known when clay is known and not the potter, neither the different tools used in the production of vessels, etc. The “all-knowingness”
resulting from the knowledge of Brahman must be understood “in conformity with the logic
of the non-difference of the material and its products.” Thus, if ākāśa is not considered as a
product of Brahman, it will remain unknown even when Brahman is known. The simile with
milk and water is also not tenable. The knowledge of water acquired through the knowledge
of milk is not complete knowledge, for water is known only indirectly through the knowledge of milk. The water may be there, but there is no way to be sure. The all-knowingness
referred to in the śruti entails that all existents are creations of Brahman, and so ākāśa
must be taken to be created.
In the last sūtra, Śaṅkara resorts to logic in order to demonstrate that ākāśa is an effect, a
creation of Brahman. The sūtra - yāvadvikāram
. tu vibhāgo lokavat - states that all products
in this world, a pot, a pitcher, a jar, etc., are separate entities. Śaṅkara simply extends
this reasoning to ākāśa. Since ākāśa can be conceived as something separate from earth
and other elements, it must be taken as a modification (vikāra) of Brahman. The argument brings much clarity as regards the way ākāśa, as material space, was understood by
Śaṅkara. It is argued here that ākāśa is a product since it is separate from other material
bodies, such as earth and other elements. This suggests that ākāśa is conceived as something comprehensible in relation with other bodies. Conceptually, it cannot be emptied of
bodies because its existence is intimately related to, or dependent upon, them. Despite its
abstract nature, ākāśa is thus considered to have a quite reified existence in this school of
thought, as is the case with Vaiśes.ika and Sām
. khya. Yet, ākāśa presents also important
metaphysical connotations in Advaita. Being the first element to emerge from Brahman, it
is often approximated to Brahman, or even taken as one of its synonyms (BSB I.1.22, 3.14,
3.41).
Śaṅkara then refutes the various arguments raised by the siddhānta ekadeśı̄. He first argues
against the Vaiśes.ika claim that the nature of ākāśa is by definition incompatible with any
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causal dependence. According to Vaiśes.ikas, any inherent cause (samavāyi ) leading to the
production of an effect consists in a variety of materials of the same class (ex : many cotton
threads produce a cotton fabric). It is argued that we cannot find such a cause in the case
of ākāśa. But, it is argued, this rule is not universally true since, in certain instances, an
effect can be produced from materials belonging to different classes (ex : a rope made of
cotton yarn and cow’s hair). Moreover, it is possible that an effect be produced from a cause
consisting of a single material, such as curd produced from milk alone. For these reasons, it
is logical to argue that ākāśa evolved out from Brahman alone, which is at once the efficient
and material cause of the world.
Śaṅkara then refutes the claim that since there can be no distinction between the nature
of ākāśa before and after its creation, ākāśa cannot be created. He points out that in the
Vaiśes.ika philosophy itself, sound is considered to be the specific quality (viśes.agun.a) of
ākāśa. Since sound did not exist before creation, the nature of ākāśa after its creation necessarily differs from that before. This is also justified by the śruti which declares Brahman
to be anākāśam (BrU III.8.8), i.e. free from the characteristic of space. In his next argument, Śaṅkara dismisses the view that ākāśa has no origin because it is all-pervasive while
other created elements are not. For Advaitins, Brahman is the only all-pervasive entity, not
because it is in physical contact with all entities - which is impossible for it is relationless
- but because it is the cause and essential nature of every entity that exists. In this specific sense, ākāśa cannot be all-pervasive although it is in a purely spatial sense. Finally,
it is argued that ākāśa is impermanent because it possesses impermanent qualities, such
as sound. For Advaitins, the relation that exists between substance and quality is that of
“identity-in-difference” (tādātmya). Sound is essentially non-different from its substratum,
ākāśa, and therefore one must accept that ākāśa is impermanent as sound is.
4. Reflections in the light of philosophy of physics
As one can see from the previous discussion, the origin of space was matter of much reflection and debate among Indian philosophers. In consonance with their own metaphysics,
they gave a different ontological status to space, and consequently had a different conception of its origin also. While the proponents of Vaiśes.ika thought of space as being eternal,
those of Sām
. khya and Advaita conceived space to be a product of evolution, thus having an
origin and a finite existence. It is fascinating to see how, though we know much more about
the physical world than at any time before, the same pressing questions seem to inhabit
physicists and philosophers nowadays : is space created or not ? Or is it the manifestation
of something more fundamental ? Can we even talk about the “creation” of space ? Such
questions have been dealt extensively by physicists and philosophers of physics since the
formulation of Einstein’s theory of relativity. Before Einstein, space was but absolute space,
a vast and immutable container in which things and events were taking place. But with the
discovery that space and time are intimately related to each other, as well as with gravity,
a new way of reflecting upon space became necessary.
Another theory that challenged our conception of space is quantum physics. Quantum
theory is primarily used to describe phenomena at the atomic and subatomic levels. In only
three decades, starting with Planck’s quantum hypothesis in 1900, this theory completely
7
shattered our understanding of the atomic world. What it tells us is that the physical reality corresponding to atoms is radically different from that of classical entities, like particles
and waves. Why and how this difference came to exist has been topic for much debates
among the early quantum physicists, and is still today. In the late 1920s, quantum field
theory (QFT) emerged as a result of the application of quantum theory to classical fields,
an endeavour that eventually culminated in the elaboration of the standard model of particle physics in the early 1970s. Quantum electrodynamics (QED) is the first quantum field
theory, and also the model for all subsequent ones as it is the most precise of all physical
theories that exist nowadays. As we shall see, the worldview set forth in QFT also brought a
significant in our conception of space, especially regarding the nature of the vacuum. In the
last decades, the major challenge has been to build a theory that would explain how gravity
behaves at the microscopic level, thereby unifying under a single conceptual framework the
four forces of nature. Such a theory is yet to be formulated, which is also experimentally
verifiable.
4.1 Space as a manifestation of the gravitational field
In special theory of relativity (SR), the Newtonian notions of absolute space and time are
discarded : space and time become relative to the motion of the observer, and are thus
measured differently by observers in different states of motion. This is a consequence of the
“principle of relativity”, which maintains that the laws by which the state of a physical
system undergoes change are the same in every inertial frame of reference, i.e. in uniform
translatory motion. In general theory of relativity (GR), this principle is extended to all
frames of reference including the non-inertial ones, such as those involving acceleration and
gravity. In particular, this theory shows that the gravitational field is intimately linked to the
geometry defined by space and time, or the spacetime continuum, which in turn is directly
related to the matter-energy content. The profound insight of Einstein has been to show
that space and time do not provide an absolute background to the world, but are dynamic
and interdependent to the rest of the world. As counterintuitive as it seems to be, general relativity’s predictions have been confirmed with great success in all experiments up to date.19
Among the several philosophical problems raised by this theory, there is the old ontological
problem of substance and of the “original stuff” of the world. What is the fundamental
existent of the world, upon which depends every other existent ? In fact, a correct interpretation of GR inevitably depends upon which of its major entities - matter, spacetime or
field - is taken as the basic ontology20 ; it also requires that we understand well the relations
between them. In his early years, quite influenced by the philosopher Ernest Mach, Einstein
took massive bodies as the only physical reality, that which determined the gravitational
field as well as the spacetime geometry. But soon he realized that this could not be true as
there exist vacuum solutions to the gravitational field equations : the field was thus ontologically more fundamental than massive bodies. He also understood that the gravitational
field specifies the very structure of spacetime (i.e., the metric), that is, that the geometry
of spacetime is a manifestation of the gravitational interactions. In his final years, Einstein
thus took the gravitational field as the fundamental reality underlying both matter and spacetime. This particular ontology is referred to as a field ontology in philosophy of physics.21
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In SR, the basic ontology is the spacetime continuum for what is privileged in this theory is
the inertial frame of reference, which defines space and time for a certain observer. But in
GR, as far as the field ontology is concerned, there is no such preference for inertial frames
of reference : the massive bodies inherit their spatio-temporal properties from the spacetime
geometry, which is itself determined by the gravitational field. Hence, there exists no real
vacuum or empty space in GR because neither matter nor spacetime can be thought of
without an underlying gravitational field. And thus, Einstein maintains :
There is no such thing as an empty space, i.e., a space without field. Space-time does
not claim existence on its own, but only as a structural quality of the field.22
In empty spacetime, the gravitational field alone constitutes the geometry, or metric, of
spacetime. When massive bodies are present, it is the gravitational field interacting with
matter that plays this role. Einstein’s theory of general relativity is thus primarily a field
theory.
Before Einstein, all objects were conceived to dwell somehow in space and time. After GR,
we had to conceive of space and time as relative and dependent upon a more fundamental
substance, i.e. the gravitational field. What then about the field itself ? Does it also depend
upon a more basic existent, some form of matter or another field perhaps ? This indeed was
the intuition of Einstein, who thought that both electromagnetic and gravitational fields
were manifestations of a more fundamental field, the so-called non-symmetrical total field.
Until his death in 1955, he worked upon the idea of a unified field theory, yet without
any major breakthrough. The main reason is that electromagnetism is a force that is active at the quantum scale, and that the continuous (differential) geometry on which GR
is based is hardly reconcilable with the discrete worldview of quantum physics. Moreover,
the equations of GR break down under extreme conditions, such as in the Big Bang of an
expanding universe or in black holes, because the gravitational field, the curvature of spacetime and the density of matter become infinite. This is the singularity problem.23 Without
a theory that explains how gravity behaves in these conditions, which requires that we take
quantum physics into account, there is no way to define what underlies the gravitational
field. The nature of the “fundamental substance” of the world thus remains nebulous in GR.
4.2 The nature of empty space in QFT
The idea of a unified field theory, first intuited by Einstein, came back to the fore in the
mid-1970s through quantum field theory (QFT). QFT originated in the 1920s from the
endeavour to describe the electromagnetic field in accordance with the laws of quantum
physics. Another motivation came from the need to reconcile quantum physics with special
theory of relativity. Since then, QFT has emerged as the most powerful language for describing the subatomic constituents of the physical world and the laws governing them. Also,
this theory has contributed significantly to the development of cosmology and astrophysics,
for it allows to describe the universe in its very beginnings, at a time when it was extremely
small and compact. The basic idea underlying this theory is that each individual particle is
in fact the quantum of a specific field, called quantum field : a photon is the quantum of the
quantum electromagnetic field ; the electron of the electron field ; and so on. In quantum
mechanics, each physical system is associated with a certain wavefunction, which provides
9
a complete description of the system. In QFT, the same wavefunction is taken as a classical field to be quantized, thus giving rise to the notion of quantum field. One of the most
important features of this theory is that each quantum field is involved in the creation and
annihilation of its associated particles, or quanta. Such process is not taken into account in
quantum mechanics, in which the number of particles in a given system does not change.
Since a decade or so, QFT has engaged the attention of several philosophers of physics. Of
much concern is the determination of the basic ontology of QFT.24 Historically, this problem is closely connected to the interpretation that is given of the wavefunction in quantum
mechanics.25 To put it briefly, de Broglie and Schrödinger held a realistic interpretation of
the wavefunction, that is, a classical field ontology. The wavefunction has a physical reality for it is endowed with energy and momentum, whereas the quantum particles have no
individuality of their own. On the other hand, Born was rejecting the reality of the wavefunction, and was in favour of a particle ontology. Though the particle shows no identity,
the wavefunction cannot itself claim for physical reality ; it is only a mathematical tool that
gives the probability of finding the particle in a certain state. Of course, both ontologies
present their own difficulties, and there is still no agreement today as to which ontology
should predominate over the other. In QFT, the situation is different for the field is involved
in the process of creation and annihilation of particles, and thus presents a more substantial
character. In QFT, indeed, the quanta that emerge from the quantum field are not classical particles since they do no possess any permanent existence or individuality ; also, the
quantum field is not a classical field because it has no continuity. The fundamental entity
in QFT thus corresponds to a new kind of field, more dynamic in nature because it has the
property of generating particles.26
Given this ontology, a major shift in our conception of “empty space” takes place. Since the
whole world is composed of quantum fields interacting with each other, there is no space
in the universe where there is no field.27 More important, when the number of quanta is
equal to zero, i.e. when space is empty of material bodies, the field is still present and its
effects can be detected. This is entailed by Heisenberg’s uncertainty principle (1927), which
maintains that the energy of the quantum field in its vacuum state must always be superior
to zero. Recalling that energy is convertible into matter, the principle thus implies that a
certain amount of energy, in the form of particles, be generated from the vacuum within a
time allowed by the uncertainty principle (∆E∆t >∼ h̄). Such transient particles are called
virtual particles, because they cannot be directly observed with any instruments, though
their presence can be inferred from physical effects like the Lamb shift and the Casimir
effect. When two particles interact, there is a whole bunch of virtual particles that are exchanged between them ; it is through such an exchange that interaction (electromagnetic,
etc.) is mediated from a particle to the other (photons, etc.). The vacuum described by QFT
- called the quantum vacuum - is not empty at all, but the locus of continuous ephemeral
fluctuations of matter-energy.
The recognition that the vacuum is somehow substantial is however in contradiction with
SR. According to this theory, the vacuum is a state of zero energy, zero momentum, zero
charge, etc. If we consider energy and momentum to characterize what we call a substance
in physics and philosophy of physics, the vacuum cannot be conceived as a substance. On
10
the other hand, the fluctuations in the vacuum tell us that the vacuum must be something
substantial, because it is able to generate substantial particles. Cao qualifies this problem
as “the most profound ontological dilemna in QFT.”28 The solution he proposed is that the
vacuum consists in a kind of “pre-substance, an underlying substratum having a potential
substantiality”. When this pre-substance is excited, it becomes a substance in the form
of particles endowed with energy and momentum. But what is the nature of such “presubstance” ? What makes it generate substantial particles, and what principle governs this
generation ? Such and similar questions have not been convincingly answered up to now.
Like in GR, the nature of the “fundamental substance” remains nebulous in QFT.
5. Discussion
Unlike the Newtonian concept of absolute and eternal space, the space described in GR is
not absolute but depends upon the gravitational field for its existence. According to this
theory, there is no empty space at all because the field always remains present even when
there is absence of massive bodies. In QFT, “empty space” is conceived as some sort of
pre-substance, preceding and giving rise to all the constituents of the world. Here also,
the notion of empty space is rejected and replaced by the notion of an all-pervading and
dynamic field, called the quantum field. Yet, because GR and QFT have not been reconciled up to now, we are unable to address the fundamental nature of the vacuum, or what
underlies the gravitational field. Moreover, the Big Bang model does not tell us how the
laws of nature and constants of the universe got defined at the beginning of the universe. It
is thus impossible, in the present state of understanding, to pinpoint with precision what
underlies the vacuum and its potentiality for giving rise to substance, or what sustains the
gravitational field of GR. Hence, in only few centuries, a major shift has taken place in our
comprehension of space. From the belief that space is something ultimate, beyond which
nothing material seems conceivable, we have move towards the conception that there is
something beyond space, upon which the latter depends for its existence.
Looking at the various discussions that took place between Indian philosophers on the nature of ākāśa, one feels himself in a similar intellectual atmosphere. That is not to say that
the concept of ākāśa, as unfolded by these philosophers, is identical with the concept of
vacuum in QFT for instance. If some similarities can perhaps be noted - for instance, both
quantum vacuum and ākāśa are all-pervasive and the loci for the creation and annihilation
of other physical entities - they belong to two different traditions, and have evolved in a
quite different historical and conceptual environment. What can be noted, however, is that
Indian philosophers were also conceiving space in a variety of ways. We find that within
each school, space is endowed with more than one meaning. In Vaiśes.ika, ākāśa is first
taken as a reified element, connected with sound and hearing, and also described on a par
with immaterial and eternal substances. In Sām
. khya, ākāśa is considered as a mere product
of prakr.ti, also connected with sound ; but with the revision made by Vijñānabhiks.u, it
becomes associated with the potentiality for change in prakr.ti. The word ākāśa is also used
in a variety of senses in Advaita literature. Beside being an element endowed with sound as
its quality, it is also taken as an entity presenting deep affinities with Brahman, or Ātman.
Each school thus presents an understanding of space that differs considerably from others,
for each school has its own specific metaphysical and epistemological premises about the
11
world. The richness of ways with which space has been looked upon in the Indian tradition
is something that one also finds in contemporary philosophy of physics.
The second point to be noted is that despite the historical gap separating Indian philosophers from philosophers of physics, they came to a similar conclusion with reference to the
origin of space. We noticed already that in the last century, the crucial scientific discovery
about space has been to realize that it depends upon something else for its existence, that
it is neither eternal nor absolute. It is remarkable that both Sām
. khya and Advaita arrived
at the same conclusion by adopting a completely different approach. In Sām
. khya, indeed,
prakr.ti is the fundamental substance out of which the whole physical world emerges, including ākāśa itself. Similarly, in Advaita, ākāśa is the first element to emerge from Brahman,
the material and efficient cause of the world. Like every other phenomenal existent, Advaitins define ākāśa to be mithyā, meaning that it owes its existence to something else, i.e.
Brahman. Of course, such similarity with modern physics does not mean, as some would
like to say, that Indian philosophers were endowed with a special faculty of discrimination
that allowed them to see what experiments show us today. What it indicates is that despite
adopting different approaches to reality, both Indian philosophers and physicists had a similar insight about the origin of space, namely, that it cannot be ultimate but must depend
upon something more fundamental for its existence. As Hiriyanna notices, this viewpoint
had no real equivalent in Western thought until quite recent times.29 From the viewpoint of
the history of ideas, it is thus a significant event that numerous Indian philosophers adopted
this philosophical view centuries ago.
6. Conclusion
It was noted that both Advaitins and physicists share the conception that space is the
product of something more fundamental. At the same time, they are both challenged in
describing the nature and origin of what is more fundamental. Somehow, in both systems,
space resides at the boundary of what is known and unknown : beyond, it is terra incognita. However, the boundary in question has a different shape and connotation in both
systems. For Advaitins, what lies beyond space is not a pure Unknown, nor a Nothingness,
but That which makes the world evident to the individual, i.e. the non-dual Brahman,
the core Subject. The point here is that Brahman is not simply an object of thought that
one can perceive and analyze, but is something to be experienced, or discovered, through
contemplation and the deep understanding that there is “in reality” no duality whatsoever.
Rational or logical thinking ultimately does not lead to this understanding as it presupposes a duality between subject and object. In fact, it is such duality that is the source
of one’s misunderstanding about Brahman, which is pure awareness. The boundary is thus
not between the known and the unknown, understood in a mere logical sense, but between
mithyā and satya, appearance and reality.
As far as physics is concerned, it requires a “real” distinction between subject and object,
between observer and observed. What lies beyond space is not pure awareness but, it is
expected, an “object” to be studied, analyzed, elucidated, and that can be known through
good insights and better resources. This is an epistemological position which differs radically from that of Advaitins. The boundary here is not between appearance and reality but
12
between what is unknown to our present means of investigation, and what we actually know
about the physical world. It is revealing to see how both systems envisage differently what
is beyond the boundary, and how they proceed in different ways to acquire this knowledge.
Nonetheless, in trying to unravel the Unknown, the same fundamental question seems to
inhabit ancient philosophers as well as modern physicists : What is That by knowing which
everything else is known as well ? This question, though addressed by thinkers of all civilizations of all times, still remains alive, approached but never possessed, pushing seekers
of around the world to always refine their understanding of the universe and what is beyond.
Notes
The English translation used for the Upanis.ads and the Brahmasūtrabhās.ya in this paper
is that of Swāmı̄ Gambhı̄rānanda.
1. For an excellent historical survey of the concept of space from Antiquity to modern times,
please refer to Max Jammer’s Concepts of Space : The History of Theories of Space in Physics, Cambridge/Massachusetts : Harvard University Press, 1954.
2. Several books have been published on the subject since then. To mention a few : H.
Reichenbach, The Philosophy of Space and Time (New York : Dover Publications, 1957) ;
L. Sklar, Space, Time and Spacetime (Berkeley : University of California Press, 1977) ;
M. Friedman, Foundations of Space-time Theories : Relativistic Physics and Philosophy of
Science (New Jersey : Princeton University Press, 1986) ; J. Earman, World Enough and
Space-time : Absolute versus Relational Theories of Space and Time (Cambridge : MIT
Press, 1992) ; N. Huggett, Space from Zeno to Einstein (Cambridge : MIT Press, 2002).
3. W. Halbfass, On Being and What There Is : Classical Vaiśes.ika and the History of Indian
Ontology (New Delhi : Sri Satguru Publications, 1992), pp.29-31.
4. In the last decades, a number of Western and Indian scholars have undertaken serious
studies on ākāśa. The following are the most complete papers on the subject : P.C. Divanji,
Brahman-Ākāśa Equation : Its origin and Development, Bombay : Bharatiya Vidya Bhavan,
9, 1948, pp.148-73 ; I.H. Jhaveri, The Concept of ākāśa in Indian Philosophy, Annals of the
Bhandarkar Oriental Research Institute, vol.37, 1956, pp.300-07 ; S.C. Chakrabarti, Ākāśa,
in : Kalātattvakośa, vol.3, edited by B. Bäumer (New Delhi : Indira Gandhi National Centre
for the Arts, 1996), pp.103-41 ; V. Lysenko, The Vaiśes.ika Notions of ākāśa and diś from
the Perspective of Indian Ideas of Space, Poznań Studies in the Philosophy of the Sciences
and the Humanities, vol.59, 1997, pp.417-47 ; W. Halbfass, Space or Matter ? The Concept
of ākāśa in Indian Thought, in : Mind, Matter and Mystery : Questions in Science and
Philosophy, edited by R. Nair (New Delhi : Scientia, 2001).
5. We are aware of only one serious study on the subject, which however tends to overlook
the differences between Indian philosophy and modern physics : K.K. Mandal, A Comparative Study of the Concepts of Space and Time in Indian Thought (Varanasi : Chowkhamba
Sanskrit Series Office, 1968).
13
6. The list of padārthas has been subject to many changes in the history of Vaiśes.ika. As an
example, the classification given by Praśastapāda largely differs from that previously established by Kan.āda. In contrast with Praśastapāda, Kan.āda considers non-existence (abhāva)
as a padārtha and accepts only the first seventeen qualities (gun.as) of Praśastapāda’s list
of twenty-four qualities.
7. In the Padārthadharmasam
. graha (p.58), a substance (dravya) is defined to be endowed with qualities (gun.as) and not being located in another susbstratum (ato gun.avattvād
anāśritatvāc ca dravyam). In the Vaiśes.ikasūtra (VS I.1.14), substances are described as possessing motion and qualities, and as inherent causes (kriyāvad gun.avat samavāyikāran.am
iti dravyalaks.an.am).
8. Detailed reasons are provided in textbooks on Nyāya-Vaiśes.ika as to why ākāśa is the
only substance that can be the bearer of sound. For instance, a good account is provided in :
S. Bhaduri, Studies in Nyāya-Vaiśes.ika metaphysics (Poona : Bhandakar Oriental Research
Institute, 1975).
9. For a more detailed discussion on the concepts of diś and ākāśa in Vaiśes.ika, please refer
to Lysenko (1997) and Halbfass (2001).
10. S.K. Sastri, A primer of Indian logic according to Annambhat..ta’s Tarkasaṁgraha (Chennai : The Kuppuswami Sastri Research Institute, 1998), p.69.
11. Halbfass (2001), p.88.
12. Each gross element is conceived to be manifold and to consist of finite particles called
paramān.us (Yoga-sūtra-bhās.ya : I.40, 45 ; III.44, 52.) However, these particles differ from
the atoms in Nyāya-Vaiśes.ika, which are taken as the building blocks of elements, partless,
indivisible and eternal. Though the atom is similarly defined as the smallest unit of matter
in Sām
. khya, it differs by being allowed to have parts. This arises from the conception that
the whole is always inseparably connected with its components parts (as the effect and its
cause) in Sām
. khya and so the substance, however small it is, can never be said to be partless. See : P. Chakravarti, Origin and development of the Sām
. khya system of thought (New
Delhi : Munshiram Manoharlal Publishers Pvt. Ltd., 1975 [1951]), pp.251-52 ; M. Hiriyanna,
Outlines of Indian philosophy (Delhi : Motilal Banarsidass Publishers, 2005 [1993]), p.276.
13. Jhaveri (1956), pp.301-02.
14. For a detailed discussion on the subject : K. Bhattacharyya, Studies in philosophy, vol.1,
Calcutta : Progressive Publishers, 1956, pp.169-70.
15. The translation of this passage has been found in : Sām
. khya : a dualist tradition in
Indian philosophy, in : Encyclopedia of Indian philosophies, vol.4, edited by G.J. Larson
and R.S. Bhattacharya (New Delhi : Motilal Banarsidass Publishers, 2006 [1987]), p.395.
Commenting this passage, Radhakrishnan maintain that empirical space and time are not
the products of kāran.ākāśa but kāran.ākāśa itself, particularised by conjuncts (upādhi ) in
14
the form of coexistent things in space and moving bodies in time. See : S. Radhakrishnan,
Indian philosophy, vol.2 (London : George Allen & Unwin Ltd, 1962 [1923]), p.277.
16. In the case of the production of a cloth, the inherent cause consists in the threads, the
non-inherent cause in the union (sam
. yoga) of the threads, and the efficient cause in the
weaver.
17. The example cited in this context is that of someone going to a potter’s house on a
specific day, who sees that there is clay, potter’s wheel, etc. The next day, he notices many
vessels made of clay and says : “It was all but clay alone the other day.” By saying that,
he means that the products of clay alone were not present the previous day, and not the
potter’s wheel, etc. Similarly, the expression “one only’ refers only to the products or effects
of Brahman, and not to the uncreated ākāśa.
18. When one looks at the milk, which is mixed with water, both milk and water are perceived. By analogy, when one knows Brahman, which is indistinguishable from ākāśa, both
Brahman and ākāśa are known.
19. As an example, in 1919, the British astrophysicist Arthur Eddington conducted an experiment in Africa to confirm that the gravitational field of the sun “bends” light, an effect
predicted by GR. During the experiment, he successfully observed, near the rim of the occluded sun, the light coming from stars located behind the sun. This would not have been
possible if the gravitational field of the sun did not bend the light from the stars.
20. T.Y. Cao provides the following definition of “ontology” in the context of physical
theories : “In contrast with appearances or epiphenomena, and also opposed to mere heuristic and conventional devices, ontology as an irreducible conceptual element in the logical
construction of reality is concerned with a real existence, that is, with an autonomous existence without reference to anything external.” See : T.Y. Cao, Conceptual developments of
20th century field theories (Cambridge : Cambridge University Press, 1997), p.10.
21. This is, for instance, the position taken by T.Y. Cao in his book (Cao, 1997). For more
details and references on this subject, please consult : Cao (1997), pp.90-122.
22. A. Einstein, Relativity and the problem of space, in : Relativity : The Special and the
General Theory (London : Methuen, 1954), pp.135-157.
23. At the end of 1960s, a number of theorems were proved which demonstrated quite
convincingly that any model of the universe that satisfies general relativity, given certain
reasonable conditions, must have a Big Bang singularity. However, when quantum mechanics is taken into account, in virtue of the uncertainty principle, it becomes possible that the
singularity be smeared away. For instance, in 1983, Hawking and Hartle proposed a model
in which there is no boundary to spacetime, and thus no singularity at the beginning of the
universe. See : S. Hawking, The Edge of Space-Time, in : The Tests of Time : Readings in
the Development of Physical Theory, edited by L.M. Dolling, A.F. Gianelli and G.N. Statile
(Princeton : Princeton University Press, 2003), pp. 677-84.
15
24. The following books deal extensively with ontological aspects of QFT : Philosophical
Foundations of Quantum Field Theory, edited by H.R. Brown and R. Harre (Oxford : Clarendon Press, 1988) ; S.Y. Auyang, How is Quantum Field Theory Possible ? (New York :
Oxford University Press, 1995) ; P. Teller, An Interpretive Introduction to Quantum Field
Theory (Princeton : Princeton University Press, 1995) ; T.Y. Cao, Conceptual Foundations
of Quantum Field Theory (Cambridge : Cambridge University Press, 1999) ; Ontological
Aspects of Quantum Field Theory, edited by M. Kuhlmann, H. Lyre and A. Wayne (Singapore : World Scientific Publishing, 2002).
25. For a general review of the various interpretations of the wavefunction, see : M. Jammer,
The Philosophy of Quantum Mechanics (New York : McGraw-Hill, 1974). Here, we followed
mainly Cao (1997), pp.144-152.
26. For a more detailed discussion, see Cao (1997), pp.158-73, and references in footnote 24.
27. However, it must be kept in mind that in QFT quantum fields exist in space and time.
The unification of spacetime with fields, done in GR with reference to the gravitational field,
is not achieved in QFT. We do not discuss here the peculiar ontological status of spacetime
in QFT, but simply presents its conception of empty space, or quantum vacuum.
28. Cao (1997), p.176.
29. Discussing the metaphysics of Sām
. khya, Hiriyanna mentions : “...Even space and time
are represented as aspects of prakr.ti and do not, therefore, exist apart from it as independent entities. This is a point which is worthy of note, for it shows that the system does
not, like the generality of philosophic doctrines including much of Western thought till quite
recent times, start by positing matter in space and time, but looks upon the primordial
physical entity as including and explaining them both.” See : M. Hiriyanna, Outlines of
Indian Philosophy (Delhi : Motilal Banarsidass Publishers, 2005), pp.270-71.
References
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