Today’s New Reason To Believe

by Dr. Jeffrey Zweerink

“Test everything. Hold on to the good.” This biblical passage underscores a central principle of the scientific enterprise. Any successful model must undergo testing that will either affirm or falsify its validity. Many scientists work diligently to provide such tests for a popular (though virtually untested experimentally) model known as string theory.

Astrophysicists Rishi Khatri and Benjamin D. Wandelt of the University of Illinois at Urbana-Champaign seek to develop an observational test for the cosmic strings (not to be confused with the strings of string theory) that result from incorporating a popular form of inflation—brane inflation—into string theory. They outline the test in a recent Physical Review article (a more lay-accessible description appears in Science Daily).

The abundant neutral hydrogen that fills the universe emits electromagnetic radiation with a specific wavelength: 21 cm. Astronomers have mapped this radiation as a function of position in the sky as shown below (see the description at the Astronomy Picture of the Day). All the structure in the image arises from material within the Milky Way Galaxy.

The hydrogen in the early universe would have produced evenly distributed 21-cm radiation (similar to the cosmic microwave background radiation). According to the research of Khatri and Wandelt, the cosmic web of strings produced during inflation will leave a signature in the 21 cm wavelength radiation which would be detectable with future instruments. However, the expansion of the universe will have redshifted the radiation roughly one hundred times to a wavelength around 21 meters. To make measurements precise enough to detect the cosmic string signature would take a square array of radio telescopes more than 100 kilometers on a side!

This daunting technical challenge demonstrates the difficulty in testing string theory. However, the rewards are worth the effort because the detection of cosmic strings would reveal to scientists the energy where gravity and quantum mechanics unify. While these tests may lie far in the future, RTB anticipates that the outcome of such tests will further demonstrate the fine-tuning (necessary for life) in the fundamental laws of physics that govern our universe.

by Jeff Zweerink

Richard Feynman

Level III multiverse

Kip Thorne

Wormholes

Hugh Everett

Black holes

The man representing the common thread linking these influential scientists and important scientific concepts, John Archibald Wheeler, passed away on April 13th, 2008, at the age of 96. During his scientific career, John Wheeler worked on topics ranging from nuclear explosions to quantum mechanics to black holes and the nature of space-time. He collaborated with Albert Einstein, Neils Bohr, and many other influential scientists. Additionally, he supervised the graduate research of many (Feynman, Thorne, and Everett) who would become leaders in their fields.

Wheeler’s scientific legacy demonstrates his willingness to address hard questions—even ones that he found philosophically uncomfortable. His encouragement of Everett’s work in quantum mechanics provides a great example.

Unlike the everyday “classical” world which we experience, the quantum mechanical world operates in a bizarre fashion. A thought experiment by Erwin Schrödinger, among the earliest to study quantum mechanics, demonstrates the strangeness. Imagine a cat confined to a box. A scientist puts one undecayed atom of a radioactive material inside the box. This material has sufficient power to kill the cat when the atom decays. At any given time, there is some probability that the atom has decayed and some probability that it has not. All this makes sense in a classical picture.

However, according to quantum mechanics, the atom exists in a state described as a combination of its original state and its decayed state. While that may make sense for the atom, the condition of the cat depends on the state of the atom. The cat also exists in a combination of a live state and a dead state! Yet when someone observes the cat, it will either be dead or alive. How the quantum world gives the observations of our “classical” world has been debated for nearly one hundred years.

The argument advanced by Hugh Everett forms the basis of the Level III multiverse. Briefly, observers will see the cat in one of two possible states—dead or alive—with some probability associated with each outcome. Everett argued that whenever a quantum event has multiple possible outcomes, each outcome actually occurs, resulting in new universes that never again interact!

Many arguments exist for and against this “many worlds interpretation” (MWI) of quantum mechanics. The MWI does present challenges to RTB’s model. However, like Wheeler, RTB scholars hope to address challenges head-on. Research into this difficult issue provides avenues to better understand how God created the universe and as well as additional tests to validate and refine RTB’s cosmic creation model. Based on its track record, we expect our creation model to pass these quantum challenges with flying colors.

by Jeff Zweerink

One biblical message Reasons To Believe consistently echoes is the mandate to weed out false ideas by testing everything. Jeremiah 33:25 makes a testable statement about the laws which govern heaven and earth, namely that they do not change. Two teams of scientists have developed the most precise clocks to date. In doing so, they have provided a powerful way to test for any variation of one of those physical laws, the electromagnetic force.

For years, atomic clocks that used a transition in cesium atoms stood as the best time-keeping devices available. However, the precision of atomic clocks depends on the size of the transition, with larger transitions giving better precision (assuming all other effects remain equal). Two papers recently published in Science describe new atomic clocks based on optical transitions five orders of magnitude larger than the microwave transitions in cesium.

The clock from one group uses neutral strontium atoms and checks the precision of the clock with another clock that uses calcium atoms. The other group built their clocks from single aluminum and mercury ions. Both clocks exceed the precision of the best cesium clocks.

All atomic transitions depend on the fine-structure constant, which also determines the strength of the electromagnetic force. Repeated tests over one year of observations with the single-ion clocks constrain variations in the fine-structure constant to less than two parts in one hundred million billion per year.

Other groups have used black holes to constrain variations in the fine-structure constant and have achieved similar results. Furthermore, observations of distant quasars (described in the 2006 Breakthroughs booklet) demonstrate that the value of the fine structure constant early in the universe matches today’s value.

Thus, continued testing affirms one critical aspect of RTB’s cosmic creation model. We live in a universe governed by constant laws of physics.