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PHVSICS OF THE IMPOSSIBLE
cally each time a new form of radiation was harnessed, a new era in
astronomy was opened up. The first form of radiation was visible light,
used by Galileo to investigate the solar system. The second form of radiation was radio waves, which eventually enabled us to probe the
centers of galaxies to find black holes. Gravity wave detectors may unveil the very secrets of creation.
In some sense gravity waves have to exist. To see this, consider the
age-old question: what happens if the sun suddenly disappears? According to Newton, we would feel the effects immediately. The Earth
would be instantly thrown out of its orbit and plunged into darkness.
This is because Newton's law of gravity does not take into account velocity, and hence forces act instantly throughout the universe. But according to Einstein, nothing can travel faster than light, so it would
take eight minutes for the information about the sun's disappearance
to reach the Earth. In other words, a spherical "shock wave" of gravity
would emerge from the sun and eventually hit the Earth. Outside this
sphere of gravity waves, it would appear as if the sun were still shining normally, because information about the disappearance of the sun
would not have reached Earth. Inside this sphere of gravity waves,
however, the sun would have already disappeared, as the expanding
shock wave of gravity waves travels at the speed of light.
Another way to see why gravity waves must exist is to visualize a
large bed sheet. According to Einstein, space-time is a fabric that can
be warped or stretched, like a curved bed sheet. If we grab a bed sheet
and shake it rapidly we see that waves ripple along the surface of the
bed sheet and travel at a definite velocity. In the same way, gravity
waves can be viewed as waves traveling along the fabric of space-time.
Gravity waves are among the fastest-moving topics in physics today.
In 2003 the first large-scale gravity wave detectors became operationalcalled LIGO (Laser Interferometer Gravitational Wave Observatory),
measuring 2.5 miles in length, one is based in Hanford, Washington, and
another in Livingston Parish, Louisiana. It is hoped that LIGO, at a cost
of $365 million, will be able to detect radiation from colliding neutron
stars and black holes.
The next big leap will take place in 2015, when an entirely new
PHVSICS OF THE IMPOSSIBLE
cally each time a new form of radiation was harnessed, a new era in
astronomy was opened up. The first form of radiation was visible light,
used by Galileo to investigate the solar system. The second form of radiation was radio waves, which eventually enabled us to probe the
centers of galaxies to find black holes. Gravity wave detectors may unveil the very secrets of creation.
In some sense gravity waves have to exist. To see this, consider the
age-old question: what happens if the sun suddenly disappears? According to Newton, we would feel the effects immediately. The Earth
would be instantly thrown out of its orbit and plunged into darkness.
This is because Newton's law of gravity does not take into account velocity, and hence forces act instantly throughout the universe. But according to Einstein, nothing can travel faster than light, so it would
take eight minutes for the information about the sun's disappearance
to reach the Earth. In other words, a spherical "shock wave" of gravity
would emerge from the sun and eventually hit the Earth. Outside this
sphere of gravity waves, it would appear as if the sun were still shining normally, because information about the disappearance of the sun
would not have reached Earth. Inside this sphere of gravity waves,
however, the sun would have already disappeared, as the expanding
shock wave of gravity waves travels at the speed of light.
Another way to see why gravity waves must exist is to visualize a
large bed sheet. According to Einstein, space-time is a fabric that can
be warped or stretched, like a curved bed sheet. If we grab a bed sheet
and shake it rapidly we see that waves ripple along the surface of the
bed sheet and travel at a definite velocity. In the same way, gravity
waves can be viewed as waves traveling along the fabric of space-time.
Gravity waves are among the fastest-moving topics in physics today.
In 2003 the first large-scale gravity wave detectors became operationalcalled LIGO (Laser Interferometer Gravitational Wave Observatory),
measuring 2.5 miles in length, one is based in Hanford, Washington, and
another in Livingston Parish, Louisiana. It is hoped that LIGO, at a cost
of $365 million, will be able to detect radiation from colliding neutron
stars and black holes.
The next big leap will take place in 2015, when an entirely new