If a Black Hole Is Truly Black and the Escape

question 117

Multiple Choice

If a black hole is truly black and the escape velocity associated with it is greater than the speed of light such that no light can escape it, where do the X-rays from the black hole candidates so far identified originate?

• A) The black hole is only black to visible radiation, but X-rays travel faster than the speed of light and so can escape.
• B) The X-rays originate from the normal star accompanying the black hole; its ordinary light is blueshifted into the X-ray spectral region by the intense gravity of the black hole.
• C) The X-rays originate from stars behind the black hole, the light from which is focused and concentrated such that it becomes X-ray radiation by gravitational focusing.
• D) The X-rays originate from the matter surrounding the black hole that is highly condensed and hence very hot because of the intense gravitational field.

---

Definitions:

Attachment

A deep and enduring emotional bond that connects one person to another across time and space, often discussed in the context of child development.

Freud

Sigmund Freud, an Austrian neurologist and the founder of psychoanalysis, a method for treating psychopathology through dialogue between a patient and a psychoanalyst.

Sucking

The action of drawing into the mouth by creating a partial vacuum, especially for extracting liquid.

Weaning

The process of gradually introducing an infant to solid food while reducing the frequency of breastfeeding or bottle-feeding.