Want to answer this question, you need to know the frequency of gravitation wave.
Circle the gravitation wave that transmit gives to double star, if the frequency of gravitation wave is F, so F changes as time, frequency F satisfies following differential equation:
From above the small equation that I solve can see, the frequency of gravitation wave as time - 3/8 second square evolution. Above K and C are invariable, t represents time.
The relationship that uses gravitation wave frequency and time can see, increase as time, the frequency of gravitation wave will be bigger and bigger, the sensitive limits of the gravitation wave detector that the frequency that at that time is gravitation wave finally exceeded us -- the radio that this is like you is to receive the signal that is less than a TV station, your radio also receives the signal that is less than airport radar.
because of this reason, the time that so gravitation wave comes over, the detector of LIGO can be explored a certain number of periodic signal, went next.
Because gravitation wave travels with velocity of light,another reason is, it crosses the earth also the time with respect to minutes minute, original time is very short. So, the time of the gravitation wave that we explore is not long. Of course, the gravitation wave time that neutron star collides and agrees the gravitation wave time that give out to be able to compare black hole collision to give out is a lot of longer.
Gravitation wave is to resemble dimple really, and the amplitude that gives out dimple in fountainhead because of it actually also is change, at the beginning scope is little, also do not measure on our earth, become only moment of close of two celestial or heavenly body, its extent just can greaten, because this ability is OK,be explored by detector of wave of our tellurian gravitation. And when moment of close of two celestial or heavenly body, the hour of mutual from them dash against is not far also. Also because of this reason, the gravitation wave that so we measure on the earth appears inside very short time only almost.
The place on put together narrates: 3 elements such as the speed of frequency, wave, amplitude decided we are impossible to be measured for long same the signal of a gravitation wave.
