A ghost is haunting our universe. This has been known in astronomy and cosmology for decades. Observations suggest that about 85% of all the matter in the universe is mysterious and invisible. These two qualities are reflected ...
Astronomy
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Scientists have introduced a form of quantum entanglement known as frequency-domain photon number-path entanglement. This advance in quantum physics involves an innovative tool called a frequency beam splitter, which has ...
Optics & Photonics
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Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), Chinese astronomers have investigated radio emission from a rotating radio transient known as RRAT J1854+0306. Results of the study, published April ...
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency. The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency. For example, if a newborn baby's heart beats at a frequency of 120 times a minute, its period (the interval between beats) is half a second.
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