The discovery of the tomb of Tuthankhamun, with its remarkably intact contents, generated great popular interest, and still does. The contrast between the New Kingdom boy–king, whose small mummified body lies mutely at the centre of it all, and the enormous detail that the contents of the tomb offered up for interpretation, is one of the great tales of archaeology. Yuko Shiraishi uses the dimensions and the structure of this tomb for her newest installation, Netherworld, for non–archaeological reasons. Her principal point of departure was not the romantic tale of the excavation but the British Museum's 2010 exhibition of the Book of the Dead, the collections of spells and charms that codify the changing patterns of ancient Egyptian thinking over many thousands of years. She read deeply into the Egyptians' religious belief and cosmology, and started to link their ideas about death and life, mortality and vitality, to her existing absorption in many aspects of science.

This focus on science and philosophy has coincided with her experimentation with paintings characterised by points in a unified field rather than by the horizontal lines that had previously preoccupied her, and which had proved capable of sustaining such rich variation. Over recent years a new stage, and a new sense of space, have opened up, and she has made a wider range of drawings and studies than before. These drawings have taken on a new significance in Shiraishi's development of her work, and show a spirit of restless formal exploration. Many such drawings are part of her research for Netherworld; they also illuminate the changes in the ambitions of the paintings. In particular they exemplify drawing as a mode of thinking and of modelling forms of thought – a two–way process. Drawings that attempt to structure models of mythic and religious systems, the cycles of star formation, and the process of programmed cell death (apoptosis), in turn suggest forms that can be used for thinking that floats free of the functions of explanation. Many of these drawings are based on the circle. The deep appeal of simple diagrammatic forms, especially when they do not fully explain ambiguous relationships between, say, two dimensions and three, or three dimensions and four, is vividly exploited in these studies. They also display a striking contrast between the very small scale and the very large, in that their titles include frankly metaphysical proposals such as World, Star and Body.

While investigating what has changed in this new stage of her work as a painter, it is also worth noting what has not changed. The format is still, in most cases, a vertically emphasised rectangle. This slight adjustment of the absolute mathematical square to a taller format preserves a particular relationship with the vertical emphasis of the viewer as he or she stands before the painting. It provides a sense of reciprocal mirroring of a basic fact of standing that, allied to her confident and knowledgeable control of colour, gives all of her paintings a steadying and sustaining power.

Artists repeat themselves; it is a sign that an artistic proposal is being made. They also change. The pleasures of experiencing Shiraishi's work in this new stage are consistent with her earlier work, but the way those mental and physical pleasures are brought about suggests that the paintings depend on a new aspect of engagement. The move apparently described by the words, 'a move from lines to points', is also, I think, a move to a new kind of potential space in the paintings; a space where interpretation – thinking, in simple terms, about what it is that we see – interacts with and interferes with the evidence of our senses, in a productive way.

A relationship between points is not the same as a relationship between horizontal lines. The relationship between points on a flat plane, when that flat plane can also be read spatially, is ambiguous. The size and colour of the point will make it recede or advance, in a consistent or variable way, against other points. This is something we experience again and again in looking at Shiraishi's new paintings: implied relationships that do not settle into fixity. We look at the points, attempt to grasp how they connect, and often sense an implied figure, a central form that could be the principle of organisation for what we see – but because some of the points are vestigial, and vanish when not stared at, the figure remains tantalisingly changeable and motile. The sense of space in these new paintings differs from the horizontally organised works because it is frankly bigger. Although at first sight there is less in them, when we begin to perceive something, it is less abstract, and more like a centrally organised figure: not a human figure, perhaps something crystalline or molecular. Here is the largest painting in the group: a silvery grey ground animated by four points, two in pink, two in white, apparently defining the figure of a rectangle. It is untypical of the new paintings in its apparent simplicity, but the points are not in fact precisely aligned on the vertical axis. The painting is part of a universe of movement, not of settled geometry. One smaller painting, Four, is legible and immediately comprehensible as a slightly flattened square, made by four green points visible through a layer of pink overpainting. But each of the four points that define this rectangle is ghosted by a larger disc, a vestigial presence of red, just visible under the layer of pink. So even with a painting that is untypical of the group, and which offers an apparently simple rectilinear figure, a degree of uncertainty is created about what it is we see. The regularity is pulled and questioned by an only partially perceptible irregularity, with which it is twinned. These are figures, but they preserve a dynamic relationship with their ground, which is itself a field of variable texture, colour, transparency, opacity and energy. The relationship between figure and ground is never simple.

There is a strong analogy for looking at these paintings in the experience of looking at stars. Diagrams of constellations flatten out interstellar space to isolate a legible, memorable, two–dimensional form; but when looking at the night sky itself the variable magnitude and colour of the stars means we intuit, correctly or not, spatial relationships in depth, as well as the familiar or half–remembered name for what we see. However, the paintings offer only an analogy to looking at stars, they are in no way a representation of the night sky. The colour of the points or discs suggests an analogy with molecular models, and thus with visualisation and construction rather than with human vision. The colour relationships that remain the focus of Shiraishi's judgment and craft as a painter give us, at the same time, much for human vision to work on, and this interacts and interferes with the ideational space of diagrams, models and three–dimensional figures. Jinsang Yoo writes: 'For Shiraishi, the possibility of painterly colours is not limited to the properties of pigment but can be enlarged into a reciprocal network that comprises all the matter that makes up the universe. Colour is not simply paint but rather an optical mediator, and its allure is mirrored within the fundamental interconnectedness of the universe.' ¹

In describing the experience of these paintings I have used the word point, which suggests something geometrical, though many other words might be better spots, which suggest solar activity or visual interference in the eye; discs, which suggest two–dimensionality, the space of the diagram; dots, which suggest indistinctness and irregularity and with that energy; or specks, which suggest dust and matter. Many of what I call points are drawn in one colour, then painted in another, which does suggest that they are discs; some are only drawn circles, and are hardly there (dark matter, perhaps; or an equivalent of stars of the sixth magnitude, the faintest visible with the naked eye). Descriptive language fails cheerfully before this problem: there is not a right word for what I have called the 'points'.

In Netherworld, four portals or doors are fitted tightly inside each other, each with angled indications of structure at the top that suggest an unfamiliar architecture. They seem to be exploded enlargements of a central rectilinear form: each is an outline, one side of something larger. Only the innermost is clearly shown as part of a complete box–like shape. At the centre of it, resting on the gallery floor, is a diagrammatic suggestion of a recumbent human shape. So we are perhaps in some kind of tomb or sanctuary. The daylight from above is filtered into dim blue, and three lamps shine down, slowly changing their colour.

Ancient Egyptian tombs include what must be the first sculptures of false doors. Netherworld also seems to have false doors: the three outer portals exist as a set of entrances tightly jammed each within the other, not as entrances you can actually enter. The sense of an exploded, transparent form perhaps suggests a screen object that can be manipulated at will, but the physical encounter with this interlocked diagrammatic shape, and the peculiar scale and detailing, suggest something else. Each portal is differently structured, not simply a smaller version of the one it is nested inside and connected to. There is no way through here, but the space around the form can be entered. We can carefully circumnavigate, approach the figure from all angles. We can stay here, not to pry and intrude, but to share the space with whatever we think the resting form is, as the lamps adjust the light shining on it through a cycle of slow changes.

The structures that I have described as portals are made precisely from the measurements of one side of each of the four gilded wooden shrines, each of which fitted inside each other. The largest of these was fitted in a tomb chamber that left only 60 cm at each end and 30 cm on either side, and almost entirely filled the available space. The installation allows us to get close if we choose, but the human reaction to the idea of a tomb is strong. Tombs tend to be cramped and small – rooms for one occupant only. Even when built as public displays or mausolea, with spaces for visitors to approach, you do not tend to stay long in them. The walk–in tomb of Noel Desenfans and Sir Francis Bourgeois, which is incorporated into Dulwich Picture Gallery, colours daylight into unexpected dim yellow. It is the light, as much as the surprising presence of the sarcophagi, that creates such a strong atmosphere when you enter from the beautifully lit picture galleries. Shiraishi's installation, like Soane's permanent building, depends on a simple transformation of daylight for its primary effect, that of entering another world – here it is a bluish, night–time world. It is a world like ours but perhaps suggesting different rules or possibilities. Colours that we tend, intuitively, to attribute to objects as a primary rather than a secondary property, are revealed as changeable. Your eyes take time to adjust to what you see, as the altered daylight interacts with the light of the three lamps.

What you see is a figure that is lying down. This figure is modelled on the mummy of Tutankhamun, but generalised and abstracted into a figure of transformation. Shiraishi has long had an interest in 'the physical acts of sitting and standing' as phenomenological givens of our relationship to space and to the world. To these interests her latest installation adds the act of lying down. A figure lying on its back is a customary way in which death is represented in western culture, and in particular in church monuments. The association of death with peaceful sleep is a strong one, but the position in which the sculpted dead are usually placed, lying straight and horizontal, is not the way most people sleep, curled up on one side. The dead are placed on their backs to remain alert and ready for the moment of resurrection. They may have their eyes open; more usually they are portrayed sleeping. In Egypt, through thousands of years in which short generations quickly succeeded each other, the dead were represented with their eyes wide open. The constant experience of change and of the shortness of human life was in sharp contrast with the infinitesimally small changes in art production. Wide open eyes seem to be a constant through the whole culture. On the shaped coffin lids (often now displayed bolt upright), the scrolls, the shrines and sculptures in the British Museum's Egyptian galleries, I have not found an image of the dead with eyes closed. Death was considered as another stage of existence, in which the power of seeing was clearly needed.

The figure in Netherworld does not have a face we can see. Shiraishi has engaged deeply with ancient Egyptian thought, not to reproduce it, but as part of a material and aesthetic enquiry. The interest of what it means to lie down is first of all a physical and experiential one: the act of lying straight on your back is also part of life. When you lie on your back on grass, looking at the sky, the transfer of your weight to the earth is complete. It is a feeling of being completely supported – and it is a very particular way of feeling fully alive. You become aware of your being on the planet as it turns, and of the wind moving the clouds directly above you. If you are trying this at night, you will find it is one of the best ways to look at stars. One of the liberating things about lying flat in this way is that you do not choose where to look. You just look. ²

The figure is balanced, securely and delicately, on its back. At the same time its structure – three concentric bands of steel in the horizontal plane, interlocked with three arranged vertically – implies physics more than it does biology. Directed to its centre – its heart – is the cycle of slowly changing light. The changes are derived from the conventional colours for representing the life cycle of a star. The celestial bodies that have been humankind's companions since before recorded history are thus incorporated into the figure's body and its heart. ³ Shiraishi's figure lies ambiguously in a state of suspended or somehow altered animation. This is not a flat representation of death as finite, and neither is it a representation of life. Shiraishi brings together ancient Egyptian thinking about life and death – the sun god's journey through darkness and the netherworld – with aspects of normative contemporary science. We are made from star–matter. The physical continuity of matter, from the raw materials of stars, to life (and consciousness, something that has evolved) and to whatever lies beyond life, is something Shiraishi regards as worthy of our strong interest – and our wonder. She sees the broad coincidences between contemporary scientific descriptions of the cycle of matter and ancient intuitions about the cosmos (in forms of thought otherwise regarded as obsolete), as raising profoundly interesting questions.

According to Barbara Lüscher, the writings we know as the Book of the Dead 'can best be translated as "Spells for Coming Forth by Day", referring to the wish to emerge safely from the tomb in a spiritualised form.' ⁴ However, this wish was clearly understood as only to be granted for a select few. As so often with systems whose aesthetic legacy continues to fascinate, the ancient Egyptian imperial structure was crushing and autocratic. For millennia it maintained a hierarchical division of labour that was a tragic waste of human lives. There are footstools from Tutankhamun's tomb that show this enthusiasm for domination with absolute clarity. Each is decorated with foreign slaves, lying down in rows, head to head, to be trodden upon by the supreme king. ⁵ These prostrate figures can perhaps be seen as a counter–version of the motif of the mummified figure lying down, whose ba ('spirit') could travel forth by day: figures who, in life, endured absolute domination.

Egypt sits at one end of the traditional story of art, through which its thinking about the uncertain relationship between death and life has remained visible. In Historical Grammar of the Visual Arts, Aloïs Riegl wrote: 'No obsolete worldview, once overcome, vanishes instantly from the face of the earth. Although it might not persevere as a deep–rooted conviction, it can, thanks to the pressure of tradition, continue to reverberate for centuries in outer forms. These forms play the most important role in the visual arts.' ⁶ Ancient Egyptian art and thought have had a particularly long and curious afterlife, and remain potent in the imagery and imagination of our own culture.

Shiraishi's engagement with ancient Egyptian thought is part of the democratic culture of the contemporary museum, where mummies have for a long time been significant ways to learn about death (as have pets). The galleries at the British Museum are always filled with the sound of children. This is not the kind of afterlife the Egyptians sought or can have expected, but we can be glad about it.