With fresh approaches to quantum gravity, the big questions about the beginning of the universe and the possibility of time and space as particles are now seriously being considered.

The problem with Einstein's universe is that it lacks an underlying quantum theory. Physicists now believe that quantum physics is more fundamental than classical physics. As with all forces in nature, except for gravity, there is a classical theory and a fundamental quantum theory. For example, electromagnetism is a classical theory, and underlying electromagnetism, is quantum electrodynamics. Physicist Fotini Markopoulo Kalamara with the Perimeter Institute for Theoretical Physics do not think that gravity should be exempt from this pattern. Classically, Einstein's theory of general relativity describes gravity, but what is yet to be found is the underlying theory, quantum gravity.

"Space and time are not at all our daily intuitive notions of three-dimensional space surrounding us and the time of our clocks; scientists want to know what space and time really are, and we do not yet know that," she said.

The tiny scale at which the microscopic structure of space and time becomes observable is the Planck scale. To get an idea of how small that is, imagine the ratio between the size of the earth and the size of a nucleus. The nucleus is a 100 trillion trillion times smaller than the earth. Now go down another 100 trillion trillion times: this is the Planck scale, where our understanding of space and time breaks down.

Yes in spite of the amazingly tiny scale, researchers can still do testable science. "Consider matter; we know that matter is made of atoms," she said. "However, scientists in the 1900s did not know that and were doubtful that we could ever test atomic theories of matter. The situation is similar with space and time. Are there atoms of space/time, and if so, can we 'see' them?" ** >from ***Quantum physicist speaks on possibility of space/time atoms. february 15, 2003

**related context**

> chandra discovers 'rivers of gravity' that define cosmic landscape. august 1, 2002

**> **search for gravity waves: another window into the universe. december 10, 2001

**> **GLAST Mission. GLAST (Gamma-ray Large Area Space Telescope) is a next generation high-energy gamma-ray observatory with launch anticipated in 2006. Possibilities of using gamma-ray bursts to detect quantum gravity effects (i.e indirectly detect space-time atoms).

**> **About the Perimeter Institute for Theoretical Physics. Institute established itself as an international focal point of cutting-edge research in foundational theoretical physics, pursuing research in quantum gravity, string theory, quantum information theory and foundations of quantum mechanics.

**imago**

> instrument variation for a planck scale

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