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Our Expert Voices conversation on space.

You may have heard that space is expanding, or that the fabric of space-time ripples quite literally like a wave. These are absolutely true – and awesome – statements, but what do they imply about the nature of space?

Concepts like expanding space or gravitational waves often lead people to think of space as having existence in and of itself. But space has no meaning without distinct objects; a truly empty universe is no universe at all. One might object that in a vacuum, virtual particles pop into and out of existence – but then such a universe isn't really empty, is it?

The expansion of the Universe, gravitational waves, and other phenomena are the function of physical objects acting according to physical laws; they do not necessitate that space itself physically exists. Until a future theory of quantum gravity weighs in on the issue, there is no reason to think of space as a thing.

Bottom line: Space is not a thing. Space is merely the only way to conceptualize the existence of distinct things in the Universe, just as time is the only way to conceptualize a Universe in which things change.

Other voices in the conversation:

Sean Carroll, theoretical physicist, California Institute of Technology: Space is overrated

Izabella Laba, mathematician, University of British Columbia: We can work with space without understanding its essence

David Albert, philosopher, Columbia University: Maybe there is no space

Go deeper

USAID chief tests positive for coronavirus

An Air Force cargo jet delivers USAID supplies to Russia earlier this year. Photo: Mikhail Metzel/TASS via Getty Images

The acting administrator of the United States Agency for International Development informed senior staff Wednesday he has tested positive for coronavirus, two sources familiar with the call tell Axios.

Why it matters: John Barsa, who staffers say rarely wears a mask in their office, is the latest in a series of senior administration officials to contract the virus. His positive diagnosis comes amid broader turmoil at the agency following the election.

Bryan Walsh, author of Future
3 hours ago - Health

COVID-19 shows a bright future for vaccines

Illustration: Annelise Capossela/Axios

Promising results from COVID-19 vaccine trials offer hope not just that the pandemic could be ended sooner than expected, but that medicine itself may have a powerful new weapon.

Why it matters: Vaccines are, in the words of one expert, "the single most life-saving innovation ever," but progress had slowed in recent years. New gene-based technology that sped the arrival of the COVID vaccine will boost the overall field, and could even extend to mass killers like cancer.

4 hours ago - Health

Beware a Thanksgiving mirage

Illustration: Sarah Grillo/Axios

Don't be surprised if COVID metrics plunge over the next few days, only to spike next week.

Why it matters: The COVID Tracking Project warns of a "double-weekend pattern" on Thanksgiving — where the usual weekend backlog of data is tacked on to a holiday.