Consider a lemon located on the surface of a white dwarf. The lemon is observed both by an observer on the surface of the white dwarf and by a person in orbit around the white dwarf. In this unusual situation, a. the lemon will look redder to the observer on the surface than to the observer in orbit. b. the lemon will look the same color to both observers. c. the lemon will look redder to the observer in orbit than to the observer on the surface. d. neither observer will be able to see the lemon, because light will not escape from the white dwarf.

A white dwarf is a type of star that has exhausted most of its nuclear fuel. It is incredibly dense and has a strong gravitational field. These stars are often about the size of Earth but have a mass comparable to that of the Sun. This means the gravitational pull on the surface of a white dwarf is extremely strong.

Because of this, objects on the surface of a white dwarf experience significant gravitational effects. Understanding the properties of white dwarfs helps us appreciate the phenomenon of gravitational redshift, especially when considering how light behaves under such strong gravitational conditions.

The observer effect here refers to how the position of different observers can result in different perceptions of the same object, due to the influence of gravity on light.

In the context of the exercise, there are two observers: one on the surface of the white dwarf and one in orbit. An observer on the surface of the white dwarf is within a strong gravitational field, whereas an observer in orbit around the white dwarf is within a relatively weaker gravitational field.

Because gravity can stretch the wavelength of light coming from the surface of the white dwarf (a phenomenon known as gravitational redshift), the observer in orbit will see the light at longer wavelengths compared to the observer on the surface. Therefore, the lemon appears redder to the observer in orbit than to the one on the surface.

Gravitational fields are regions of space where objects experience a force of attraction towards a massive body, like a planet, star, or white dwarf. The strength of a gravitational field depends on the mass of the object creating it and the distance from the object.

For white dwarfs, these fields are extremely strong due to their high mass and small size. Light traveling from the surface of a white dwarf towards less intense gravitational fields, like its orbit, will be influenced significantly.

This influence stretches the light's wavelength in a process called gravitational redshift. Hence, understanding gravitational fields is crucial when considering phenomena like how light from a lemon would appear differently to different observers.

Light wavelength is the distance between consecutive peaks of a light wave. It determines the color of visible light, with shorter wavelengths appearing blue and longer wavelengths appearing red.

When light moves through a strong gravitational field, as it does from the surface of a white dwarf to an observer in orbit, its wavelength is stretched due to gravitational redshift. This makes the light appear redder than it would if observed from a position experiencing equal or stronger gravity.

This wavelength shift is why the lemon on the surface of a white dwarf would appear redder to someone in orbit around it compared to someone on the surface. The difference in observed light wavelength is a direct result of the gravitational influence of the white dwarf.