The animation below illustrates how gravitational waves are emitted by two neutron stars as they first orbit each other and then coalesce. Though gravitational waves were predicted to exist in 1916, actual proof of their existence wouldn't arrive until 1974, 20 years after Einstein's death.
Uroabdomen can result from various causes, but the most common is related to trauma. Damage to the kidney, ureter, bladder, or urethra may cause urine to leak into the abdomen. Some common forms of trauma that can result in a disruption of the urinary tract in cats include:
Ahh, the mysterious female anatomy. Fortunately, there is an easy answer to your question: Neither! Urine exits from a separate body part called the urethra, or the tube that carries urine from the bladder to the urethral opening. The urethral opening is the hole that is below the clitoris and above the vaginal opening.