• Choose a category
• All
• Classic-Fiction

By Root 613 0

for a life-form—say, an E. coli bacterium—settling in the split water drop, some information about the water remaining in the faucet is irretrievably lost, an effect roughly comparable with cosmic forgetfulness. But at and before the time of splitting off, there was contact between the water in the droplet and in the faucet; certain kinds of information can thus reach the drop. For instance, the chemical composition of the water, such as the relative amount of minerals it contains, does not change while a drop splits off: based on a theory for the splitting off that includes this insight, one can infer the chemical composition of water in the faucet from that in the drop, which is directly accessible and easy to determine.

Given sufficient intelligence on the part of the bacterium, there is also the possibility of indirect reconnaissance. By splitting off, the drop starts to vibrate slightly, in a way observable within the drop itself. With sufficiently precise data and a correct theory, one can calculate backward to the time when the drop split off and infer where it came from. Also in cosmology, one makes use of vibrations—matter released in the early universe and oscillating from the interplay of mutual gravitational attraction and inertia, resounding in cosmic tone colors visible in the heavenly intensity distribution of microwaves, or maybe, in the future, gravitational waves. And here one also ventures to draw conclusions about much earlier times.

FURTHER TEST POSSIBILITIES:

NEVER GIVE UP

In addition to the cosmology of the very early universe, there are further situations in which theory can prove itself in a confrontation with observations. Whether quantum gravity effects are large enough to play a sizable role in these cases remains disputed; and even if they are, consequences for our worldview may be less spectacular. But for observations of the highest sensitivity at the outermost frontiers of research, it is always important to be aware of mutually independent phenomena suggesting a new physical mechanism, as seen for the indications of dark energy—in that case, the distributions of background radiation, galaxy maps, and supernovae. Only then can one be sure that a working model indeed has a chance of applying to the whole universe. In the same way, indications for quantum gravity will be convincing only in a strong combination of independent sources.

BIG BANG NUCLEOSYNTHESIS:

COOKING UP THE ELEMENTS

During the hot phase of the big bang, the powerful thrust of the initial, possibly accelerated expansion had not only resulted in a universe of already rather large size, but also, like waves arising from a seaquake, had excited particles out of the vacuum. Space was not empty, but contained matter and energy. There was, however, too much energy for atomic nuclei or matter as we know it to exist. All the separate particles, such as the protons and neutrons forming the nuclei of atoms, just buzzed around unbound. And if perchance one of the busy protons and a neutron had come together in strong, tender bonds to form a common nucleus, they would instantly have been shattered by another energetic particle’s intrusion.

Even individual particles were very short-lived, for the high density of matter made it very likely for them to encounter their nemesis in the form of an antiparticle, each time to disappear completely in mutual annihilation—except for their total energy left in the form of photons. But particles were not eliminated altogether; the photons, when scattering off charged matter, were able to re-create pairs of particles and antiparticles, sending them back on an arduous trip to their next demise.

All this slaughter did not go on without end, for the universe expanded, thinned out, and cooled down. The energy of photons slowly dwindled until it no longer sufficed to create particle-antiparticle pairs. At first, protons and antiprotons, neutrons and antineutrons ceased to emerge from pair creation, while the production of electrons and their antiparticles, positrons, continued. With a mass