ature and extreme pressure, succeeding in
part because they avoided continuous high-intensity laser monitoring that they say can
also cause an anvil’s diamonds to fail. Eventually, as they neared 500 GPa, the black sample
became shiny and reddish. A low-intensity
infrared laser—one that wouldn’t risk stressing the diamonds—revealed a strong spike in
the sample’s reflectance, as expected from a
metal. Only then did the Harvard pair use a
different laser, in a procedure called Raman
spectroscopy, to verify the peak pressure in
the diamond cell.
Silvera and Dias concede that their reddish
silver speck could be a liquid rather than a
solid, and they have not dared to release it
from their diamond-tipped vise. But they are
confident it is a metal—a “very convincing”
claim, says Neil Ashcroft, a Cornell University
physicist who predicted the superconductive
state of hydrogen nearly 50 years ago.
Eremets and others say they need more
proof that the team has created a solid metal
or even a metal at all. “We see only one ex-
periment. It should be reproduced,” Eremets
says. He also wonders whether the team ac-
tually reached the claimed 495 GPa, because
that is usually determined through continu-
ous Raman laser monitoring. Except for the
final 495-GPa Raman measurement, Silvera
and Dias were forced to estimate pressures
from the number of turns of the screws
on their anvils. Raymond Jeanloz, a high-
pressure physicist at the University of Cali-
fornia, Berkeley, also wants to be sure the
trapped speck is pure hydrogen, because the
gasket or the diamond coating could have
broken down and reacted at high pressures.
“It has fooled people in the past,” he says.
But Silvera remains steadfast. A com-
parison of reflectance measurements from
the center of the hydrogen dot and the
surrounding gasket at 495 GPa suggests the
hydrogen in the sample is pure, he says. As
for the pressure measurement, Silvera insists
he and Dias have studied it closely and veri-
fied their calibration.
Silvera says they have just one experiment to report because they wanted to announce their result before running further
tests that could break their vise. Soon, he
says, they plan to run additional Raman
laser tests that should reveal whether the
sample has the regular atomic lattice expected of a solid metal. Eventually they will
unscrew the vice and see whether the metal
Then, they will begin the experiment
again. Claiming total victory in the “hy-
drogen wars,” as Jeanloz calls them, will
require another round or two of evidence. j
27 JANUARY 2017 • VOL 355 ISSUE 6323 333 SCIENCE sciencemag.org
Using two diamonds, scientists squeezed hydrogen
to pressures above those in Earth’s core.
President Donald Trump did not mention science in his inaugural address. That’s the norm for recent presidents, although many research- ers hold fond memories of Barack Obama’s pledge in 2009 to “restore
science to its rightful place.” Trump’s closest reference was his comment that “we
stand ready … to unlock the mysteries of
space, to free the Earth from the miseries
of disease, and to harness the energies, industries, and technologies of tomorrow.”
Now that the 45th president is on the job,
here are 10 questions that loom for science as
Trump’s rhetoric confronts political realities.
Will Trump shape 2017 spending? He must
decide whether to weigh in as Congress div-vies up some $1.1 trillion in discretionary
spending for the 2017 fiscal year that began
last October. (Current agency spending is frozen at 2016 levels through April.) The details
matter; a multibillion-dollar boost for the National Institutes of Health (NIH) is in the mix,
for example. Trump could also signal support
for controversial policy riders that would bar
agencies from enforcing environmental rules.
How will science fare in Trump’s first bud-
get? Trump is reportedly planning to un-
veil the outlines of his 2018 budget request
next month, with details to follow in May.
That will be the first real description of his
spending priorities. Will Trump follow his
predecessors in devoting about 12% of dis-
cretionary spending to research? Will he
call for deep cuts to climate and environ-
mental science, and to renewable energy
research, as some conservatives have long
advocated? No president has ever gotten
everything he wants, however, as Congress
has the final say on spending.
Who will advise Trump on science? Trump has
so far ignored pleas from science groups to
speedily select a prominent researcher to
be his science adviser. Assuming he staffs
the position, will the adviser have direct access, or report through one of several emerging centers of power in the White House?
And what will be the makeup of a blue ribbon science panel that has advised presidents since Dwight Eisenhower—Obama
called his the President’s Council of Advisors on Science and
Trump decide to
Who will run science
agencies? The real
work of managing
federal research falls
not to Cabinet secretaries, but to dozens
of less visible senior administrators.
None has yet been
Trump last week
asked NIH Director
Francis Collins to
stay on at least temporarily. Will they
be eminent scientists, as were most
of Obama’s choices? And if many hail from
industry, as has been the pattern in Republican administrations, will they command
the respect of the scientific establishment?
Will Trump’s infrastructure plan include science? Trump is pushing for massive spending to rebuild the country’s transportation
infrastructure. Many scientists and some
lawmakers have a broader vision that includes advanced computing facilities. But
this big-ticket item clashes with demands
from many Republicans to reduce the deficit, and its fate is uncertain.
The Trump era: 10 questions
New president confronts a host of science-related issues
By Jeffrey Mervis
Scientists are anxiously awaiting President Donald Trump’s policies.