Stories tagged Scientific World View

Aug
06
2006

Triangulum galaxy (M33)
Triangulum galaxy (M33)Courtesy NASA

Universe may be 15.8 billion years old

The Hubble constant, formulated by Edwin Hubble in 1929, has remained fairly constant since the 1950's. Kris Stanek, associate professor of astronomy at Ohio State, and his coauthors are publishing a paper that may change the accepted value of the Hubble constant and also the accepted size and age of the universe.

They studied two of the brightest stars in M33, which are part of a binary system, meaning that the stars orbit each other. As seen from Earth, one star eclipses the other every five days.

They measured the mass of the stars, which told them how bright those stars would appear if they were nearby. But the stars actually appear dimmer because they are far away. The difference between the intrinsic brightness and the apparent brightness told them how far away the stars were -- in a single calculation.

To their surprise, the distance was 15 percent farther than they expected: about 3 million light-years away, instead of 2.6 million light-years as determined by the Hubble constant.

Astronomers crunch numbers, universe gets bigger

This new method took 10 years to develop. To make such a drastic change to the accepted view of the universe will require additional experimentation.

"Our margin of error is now 6 percent, which is actually pretty good," Stanek said. Next, they may do the same calculation for another star system in M33, to reduce their error further, or they may look at the nearby Andromeda galaxy. The kind of binary systems they are looking for are relatively rare, he said, and getting all the necessary measurements to repeat the calculation would probably take at least another two years.

Soure article: Ohio State University Research Archive

Feb
01
2006

Connections between politics and science were clear during the State of the Union address on January 31, when President George W. Bush outlined his priorities for the nation. "We see great changes in science and commerce that will influence all our lives," Bush said, expecting the United States to "lead in oppportunity and innovation for decades to come."

Here are some of the scientific objectives the President discussed:

  • Increased science and math education—to make the United States a leader in nanotechnology, supercomputing, and the development of alternative energy sources.
  • An end to the spread of the HIV-virus, and assistance internationally to people with HIV/AIDS or Malaria.
  • Ethical regulations in science and medicine (specifically in the area of human cloning).
Oct
12
2005

A visitor to this website recently posted this question:

How is evolution proved right? How is there proof of this "chance?" There are many other ways people say the earth was created; which is right? Is there a God that created the world? Or did everyone simply evolve? Whatever you believe, how do you prove yourself right?

Here is the Science Museum of Minnesota's official position on evolution.

That said, "proof" is really the crux of the issue.

All explanations of the Earth's creation other than evolution basically say that life is too complicated to explain by natural processes; something outside of nature must have created it. The only way to prove or disprove an idea like that is to look outside of nature. And once you go outside of nature, you're no longer doing science.

Science is a way of looking at the world, asking questions about nature and looking for answers in the natural processes around us. It works on one simple rule: show us the evidence! Show us an experiment in the lab or an observation in nature, but you have to point to something real that can be seen or measured. And then you have to come up with an explanation for what you've seen. You have to test your explanation by doing another experiment or making another observation that supports you. And if the results don't match, you know your explanation was wrong.

In science, a theory is an explanation that accounts for all the evidence. Atomic theory explains how matter works. Gravitational theory explains how gravity works. And evolutionary theory explains how life has changed over time.

Evolution is both a fact and a theory. The word has two meanings. First, it means "the history of life on Earth." And there's no denying that life has changed over the last 500 million years-go to the Dinosaurs and Fossils Gallery and see for yourself. But evolution also means "the explanation of HOW those changes have occurred." Scientists use the word theory for explanations that account for all the evidence.

And there is a lot of evidence for the theory of evolution. Every fossil that's ever been found; every animal that ever lived; every cell in your body-all of these support evolution. Scientists have been poking and prodding and testing the theory for 150 years, and have written tens of thousands of papers on the subject. Evolution is the best explanation we've ever had for the history of life on earth. (In terms of experiments and observations, it has been said there is more solid evidence for evolutionary theory than for atomic theory-and no one doubts the existence of atoms!)

Evolution happens every day, all around us. The bird flu that's been in the news is an example of evolution in viruses. New breeds of farm plants and animals are examples of evolution. And every baby that is born today will inherit traits from its mother and father, and so also be an example of evolution in action.

Science is really good at explaining WHAT and HOW: what our bodies are made of, how they work, how we evolved. But one thing science cannot do is explain WHY. Why are we here? What is our purpose? What is life's meaning? For that, you need religion.

OK, so what is evolution?
Evolution, by the most basic definition, is the profound, ceaseless change in life forms through time.

Charles Darwin and Alfred Wallace were the first scientists to call this change in life over time "natural selection," although many others have contributed to the idea. (Changes in the theory of evolution have been made since Darwin's original proposal, yet his main theory stands firm.)

The theory of natural selection is based on three principles:

  • Organisms produce more offspring than can survive and reproduce.
  • Those that do survive tend to be better adapted to local environments.
  • Most adaptations are genetic, so they can be passed from parent to offspring.

Generation by generation, organisms that are better adapted to their environment in some way survive to pass on their advantageous qualities.

Evolution is not purposeful: it does not work toward a specific end or create better or worse organisms. Species evolve by adapting to particular niches in their environments, but the genetic mutations that lead to these adaptations occur by chance. An organism cannot will itself to mutate in a beneficial way. If its niche disappears, the species may become extinct or it may adapt to new conditions, but the failure to do so does not imply some kind of defect.

Evolution does not occur "for the good of a species." It operates at the level of individual organisms over many generations. A whole population does not simultaneously evolve a new trait; instead, the new trait evolves in one or a few organisms, which pass it on until the population is dominated by organisms having that trait.

Even more evidence of evolution
As humans, we share features with all living life forms, past and present. The more specific these features are, the more recently scientists think they evolved. For example, fingernails-a feature we share with all primates-evolved 30 million years ago. We have the same basic anatomical plan as all other vertebrates, which evolved 500 million years ago. And our cells'ability to use oxygen goes all the way back to our relationship with plants, fungi, and bacteria, which evolved over 1,000 million years ago.

Here are other examples of evidence for evolution:

  • Some animals have organs that serve no purpose but have a function in other species. Such a structure is referred to as vestigial. Whales, for instance, possess useless pelvic bones left over from their land-dwelling ancestors. Fossil whales are found with tiny limbs that became increasingly unimportant.
  • Many closely related species live in proximity to one another but are separated by a geographical barrier. (It was observations like this on the Galapagos Islands that helped Darwin formulate his theory of natural selection.) For example, two similar species of fish live separated by Central America: one in the Gulf of Mexico, and the other in the Pacific Ocean. They evolved when the Isthmus of Panama formed and separated their common ancestor's population into two groups. If the fish had not evolved after they were separated, the same species would live on both sides of the isthmus. And if they hadn't descended from a common ancestor, they wouldn't be so similar.
  • As we develop more types of antibiotics, new resistant strains of bacteria evolve through natural selection. Many crop pests have also evolved strategies to cope with our use of pesticides. Some species of grass have even evolved ways of thriving on industrial waste.
  • Through artificial selection, humans have developed new plants and animals. By manipulating genes, we have obtained many different types of crop plants-some produce greater yields, some produce higher concentrations of their own natural pesticides, and some are more resistant to drought. From a very basic canine type, we developed many different breeds of dogs over the last few thousand years. Artificial selection is somewhat analogous to natural selection; the difference is in the selective force-humans, instead of nature.
  • All multi-celled creatures share distinct genes for developing body plans (like plans for limbs, eyes, etc.). These genes, called homeotic genes, are incredibly similar in all animals, even among animals as different as fruit flies and chimpanzees.
Apr
25
2005

The US Postal Service will release 4 new stamps this month to commemorate important American scientists of the last century.

4 American Scientist StampsOne of my favorite science thinkers, Richard Feynman, will be featured on one of the stamps. Feynman was famous for his discoveries about Quantum Electro Dynamics, which allowed us to understand more about the very strange properties of light. While Feynman was a ground breaking scientist he also excelled as a remarkable teacher. To get a sense for his teaching abilities and to learn more about light, you should watch one of his lectures on Quantum Electro Dynamics

The stamps will also feature:

  • Geneticist Barbara McClintock - McClintock's work on genes in maize (corn) earned her the Nobel Prize in 1983. She was the first person to discover that genes are genes are transposable--they can move between chromosomes.
  • Mathematician John von Neumann - von Neumann's mathematical discoveries helped establish the field of cellular automata and many of the principles that drive modern computers today. He even extended his thories to the field of mining, proposing futuristic ways of mining the moon.
  • Thermodynamicist Josiah Willard Gibbs - Gibbs, who lived from 1839-1903, studied the physics and mathematics involved in how complex fluids move around in space. His work provided a foundation for future discoveries such as vector analysis (a type of math), quantum mechanics, and even the behavior of comets.

Do you think you will buy stamps because they have scientists on them? I will, but I'm kind of a nerd.

Mar
03
2005

In January, Harvard President Lawrence Summers created quite a stir when he suggested that one reason why there are fewer women than men working in math and science is that there are inherent differences between male and female brains. (Summer's full speech can be found here.

The comments created quite a controversy. Enter "Summers Harvard women math speech" into Google and you'll get about 28 thousand hits. Many people are reluctant to accept the idea that men and women are inherently different.

Feb
08
2005

On February 8, the British government gave a team of scientists permission to clone human embryos for medical research. Legal in the UK since 2001, this is only the second cloning project the government has allowed.

Led by Ian Wilmut, the creator of Dolly the sheep, the team plans to study motor neuron disease, or MND. The disease kills motor neurons—cells in the brain and spinal cord that control movement. MND affects about 350,000 people, and kills 100,000 each year. Wilmut's team wants to study what goes wrong in the afflicted nerve cells.