2004-3-15
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VOICE ONE:
This is SCIENCE IN THE NEWS, in VOA Special English. I'm Sarah
Long.
VOICE TWO:
And I'm Bob Doughty. On our show this week -- new developments
about a British study that frightened many parents.
VOICE ONE:
A study measures the effects of dirty conditions on child growth.
VOICE TWO:
Plus ... the mystery of dark energy.
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VOICE ONE:
Six years ago, a British study
suggested the possibility of a link between autism and the M.M.R
vaccine. Autism is a brain disorder that appears in young children.
It affects communication and the ability to relate to people and
environments. The M.M.R. vaccine is a medicine given to millions of
children to prevent three diseases: mumps, measles and rubella.
Thirteen scientists did the study. Their report appeared in the
British medical magazine The Lancet. But The Lancet has now
published a letter from ten of those scientists. One of the others
could not be reached. The ten withdrew the suggestion of a possible
link between autism and the M.M.R. vaccine. They said they wish to
make clear that they never stated that the vaccine caused autism.
VOICE TWO:
The ten scientists did not include Andrew Wakefield who led the
study. Recently he has been criticized for accepting money from
lawyers for a group of families of autistic children. The families
wanted a separate study done to support legal claims against
companies that make the vaccine.
Doctor Wakefield says his work for the families was no secret and
created no conflict of interest with his study. He is reported as
saying he still believes a possible connection between autism and
the vaccine needs further investigation. Lawyers for Doctor
Wakefield have demanded an apology from The Lancet.
VOICE ONE:
Public trust in the M.M.R. vaccine has dropped in large part
because of the nineteen-ninety-eight study. The ten scientists said
they recognize there have been major effects on public health. Some
parents in Europe and the United States have refused the vaccine for
their children. Doctors say this is a serious risk. Mumps, measles
and rubella can all make people very sick.
Since the study, other studies have shown no link between autism
and the vaccine. Some critics say a lot of money has been wasted
trying to prove that the nineteen-ninety-eight study was false. But
others have called the study "poor science." They note that only
twelve children took part.
In a commentary, The Lancet points out that the vaccine issue was
only one observation. The study dealt with bowel disease in autistic
children. The scientists reported a possible link between bowel
disease and autism. The letter just published does not dismiss that
part of the study.
VOICE TWO:
Last November, the United States government announced a ten-year
plan to study autism. Scientists know that genetics play a part, but
not much beyond that is known.
Autism research does not have a very long history. In
nineteen-forty-three, a researcher named Leo Kanner wrote about a
condition that he found in eleven children. He described it as
"extreme autistic loneliness." He said the children were unable to
relate themselves in the normal way to people and situations "from
the beginning of life."
Leo Kanner was a medical doctor at Johns Hopkins University, in
Baltimore, Maryland. His specialty was mental health in children. In
nineteen-thirty-five, he wrote what is described as the first
medical book on child psychiatry.
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VOICE ONE:
This is SCIENCE IN THE NEWS, in VOA Special English.
Unsafe water supplies and dirty conditions can slow the growth of
children. This is the finding of public health researchers from
Johns Hopkins University. Their study appears in The Lancet.
They studied two-hundred-thirty children in Peru from birth until
three years of age. This is what they found:
By age two, children from homes with the worst conditions were
one centimeter shorter than those with the best conditions. They
also had fifty-four percent more cases of diarrhea. The researchers
examined the babies once a day and measured them once a month.
VOICE TWO:
But better water supplies alone did not guarantee good health.
For example, some families kept water in large containers outdoors.
Others kept small storage containers inside their homes. Small
containers can be filled more often.
But children in homes with the small containers had more cases of
diarrhea. The researchers say this is because the containers are
usually kept uncovered. So the water can get dirty more easily. The
large containers outside are normally kept covered.
The researchers found that other conditions could also affect the
growth of children. Some of the children were from homes with a
water connection, but not a good system for waste removal. These
children were almost two centimeters shorter than those with the
cleanest conditions at home.
The study ended in nineteen-ninety-eight. Doctor William Checkley
led the study. He says safe water and good sanitation are basic
human rights.
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VOICE ONE:
American space scientists say Albert Einstein may have been right
after all about what space is mostly made of. They say they have
found the best evidence yet that some form of energy pushes at an
unchanging rate throughout the universe. Scientists today call this
dark energy.
Einstein had a different name for such a force. He called it a
cosmological constant. The German-born American physicist had a
theory that this force balanced the pull of gravity. Without it,
everything in the universe would crash together in the middle.
Gravity would prevent the opposite. It would keep objects from
spreading apart forever.
VOICE TWO:
Einstein developed this idea in support of a general belief that
the universe was static, unchanging. However, he rejected the idea
following a discovery by Edwin Hubble in nineteen-twenty-nine. The
American astronomer found that the universe was expanding.
Albert Einstein later called the cosmological constant theory his
"greatest blunder." Yet now, the space telescope named after Edwin
Hubble has gathered information to suggest this was no mistake.
VOICE ONE:
Astronomers used the Hubble Space Telescope to examine stars that
exploded thousands of millions of years ago. These stars are called
supernovas. The scientists measured light from the supernovas. Such
measurements tell much about conditions at different points in the
history of the universe.
Adam Reiss [reese] led the research at the Space Telescope
Science Institute in Baltimore. Mister Reiss says dark energy
appears to stay the same even as the universe expands. He says any
change is extremely slow, if at all. He says the universe has at
least thirty-thousand-million years left. This is even if Einstein's
cosmological constant theory is wrong.
VOICE TWO:
So that is good news. Yet the researchers were not able to offer
any new information about one question: What is dark energy?
The only thing most scientists seem sure of is that they are not
sure. Whatever it is acts in a way opposite to gravity. Gravity
pulls things together. Dark energy pushes them apart.
What if dark energy ever grows stronger than gravity? Then, it
could tear all things apart. Stars, planets, even individual atoms
would be destroyed. Scientists call this the "big rip."
VOICE ONE:
But some question all this. An international team recently
announced evidence that might conflict with the dark energy theory.
The researchers studied X-rays recorded by the European satellite
observatory XMM-Newton.
They looked at X-rays from groups of galaxies thousands of
millions of years old. They say there are ten times more of these
clusters now. Alain Blanchard is a scientist at the Astrophysical
Laboratory in France. Mister Blanchard says these results require a
high density of matter in the universe. He says that would leave
little room for dark energy.
Adam Reiss tells us he is not worried about these findings. He
studies supernovas. But he says most scientists who study galactic
clusters report findings that are similar to his own. That is, a
universe filled mostly with a mysterious force they call dark
energy.
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VOICE TWO:
SCIENCE IN THE NEWS was written by Jill Moss and Caty Weaver.
Cynthia Kirk produced our program. This is Bob Doughty.
VOICE TWO:
And this is Sarah Long. Join us again next week for more news
about science, in Special English, on the Voice of America.