How our brains track where we and others go

As COVID cases rise, physically distancing yourself from other people has never been more important. Now a new UCLA study reveals how your brain navigates places and monitors someone else in the same location.

Psychology & Psychiatry

Closer threats inspire a more primitive kind of fear

Your brain handles a perceived threat differently depending on how close it is to you. If it's far away, you engage more problem-solving areas of the brain. But up close, your animal instincts jump into action and there isn't ...


Neuroscientists create the sensation of invisibility

The power of invisibility has long fascinated man and inspired the works of many great authors and philosophers. In a study from Sweden's Karolinska Institutet, a team of neuroscientists now reports a perceptual illusion ...

Medical research

The physics behind tumor growth

Researchers at Duke University have developed a predictive theory for tumor growth that approaches the subject from a new point of view. Rather than focusing on the biological mechanisms of cellular growth, the researchers ...

Diseases, Conditions, Syndromes

Hand-held device measures aerosols for coronavirus risk assessment

Because of the role they play in coronavirus transmission, understanding aerosol concentrations and persistence in public spaces can help determine infection risks. However, measuring these concentrations is difficult, requiring ...

Oncology & Cancer

How cancer cells escape crowded tumors

Like people, cells in the human body protect their personal space. They seem to know how much space they need, and if it gets too tight, most cells prefer to break free. The mechanism enabling cells to evade crowded environments ...

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Space is the boundless, three-dimensional extent in which objects and events occur and have relative position and direction. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of the boundless four-dimensional continuum known as spacetime. In mathematics spaces with different numbers of dimensions and with different underlying structures can be examined. The concept of space is considered to be of fundamental importance to an understanding of the universe although disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework.

Many of the philosophical questions arose in the 17th century, during the early development of classical mechanics. In Isaac Newton's view, space was absolute - in the sense that it existed permanently and independently of whether there were any matter in the space. Other natural philosophers, notably Gottfried Leibniz, thought instead that space was a collection of relations between objects, given by their distance and direction from one another. In the 18th century, Immanuel Kant described space and time as elements of a systematic framework which humans use to structure their experience.

In the 19th and 20th centuries mathematicians began to examine non-Euclidean geometries, in which space can be said to be curved, rather than flat. According to Albert Einstein's theory of general relativity, space around gravitational fields deviates from Euclidean space. Experimental tests of general relativity have confirmed that non-Euclidean space provides a better model for explaining the existing laws of mechanics and optics.

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