Month: November 2019

Enlarge / Vanishing glaciers, like this one in Glacier National Park, are a clear indication of climate change. (credit: National Park Service)

The past few years have seen high temperature records set with regularity, accompanied by things like intense heat waves, coral bleaching, wildfires, and other problems. All of that has made refusing to accept the reality of climate change an increasingly untenable proposition and has left people who would rather not deal with the consequences to adopt various fallback positions. One common refrain has been the claim that climate change does pose a problem but that it's not really a crisis.

This week, it seemed like scientists had had enough of this argument, as headlines everywhere announced that 11,000 scientists had declared that we're facing a "climate emergency." And it seemed to have the desired effect, attracting extensive press coverage. But the declaration of emergency itself doesn't carry anything like the intellectual weight of the scientific reports of the Intergovernmental Panel on Climate Change, and it's actually the latest of a series of declarations with a somewhat odd history.

The warning itself

The document itself comes with a self-explanatory title: "World Scientists’ Warning of a Climate Emergency." The second sentence is equally clear, stating, "We declare, with more than 11,000 scientist signatories from around the world, clearly and unequivocally that planet Earth is facing a climate emergency."

The world of physics is a bit like a child's bedroom. After sufficient yelling, everything becomes neat and tidy, but open a drawer or look under the bed and an enormous mess is revealed. The neat agreement between experiment and quantum mechanics is a never-ending source of amazement to me. But obtaining that agreement is a bit like the fraught business of straightening out the mess under your kid’s bed.

Often, when we think about advancing physics, we turn to the things we can’t explain, like the apparent accelerating expansion of the Universe or the pull of gravity. However, we can also (destructively) test quantum mechanics closer to home by making precision measurements on the properties of atoms and ions (atoms with electrons removed).

But that requires comparing experimental results to calculated outcomes. Actual practical calculations of things like the properties of atoms and ions require taking quantum electrodynamics apart, cleaning out under its bed, and generally getting down and dirty with integrals. The hope is that at the end of it all, we can say something useful about the validity of quantum electrodynamics in our Universe.

Enlarge / The Space Launch System was created as part of a political compromise between US Sen. Bill Nelson (D-Fla.) and senators from Alabama and Texas. (credit: Chip Somodevilla/Getty Images)

For the first time, a government cost estimate of building and flying a single Space Launch System rocket in a given year has been released. This estimate of "over $2 billion" came in the form of a letter from the White House to the Senate Appropriations Committee first reported by Ars this week.

In the nearly decade-long development of the SLS rocket, NASA officials have studiously avoided providing a so-called "production and operations" cost. This is partly because it can be difficult to estimate flight costs during production, but also very likely because doing so might give lawmakers who have backed the project some measure of sticker shock. After all, a fully expendable version of the Falcon Heavy rocket, which has two-thirds of the lift capacity of a Block 1 version of the SLS rocket, can be bought today for $150 million.

After publication of the White House letter, the agency did not deny the estimate that producing and flying one SLS rocket in a given year—which is the production capacity core stage contractor Boeing may be able to reach by the early 2020s—will be more than $2 billion. The first SLS launch could come in 2021.