Name ___________________________ Date _______ Pd __
Black Hole
STEP I
A black hole is a region of spacetime from which gravity prevents
anything, including light, from escaping. The theory of general relativity
predicts that a sufficiently compact mass will deform spacetime to form a
black hole. Around a black hole there is a mathematically defined surface
called an event horizon that marks the point of no return. It is called
"black" because it absorbs all the light that hits the horizon, reflecting
nothing, just like a perfect black body in thermodynamics. Quantum field
theory in curved spacetime predicts that event horizons emit radiation
like a black body with a finite temperature. This temperature is inversely
proportional to the mass of the black hole, making it difficult to observe
this radiation for black holes of stellar mass or greater.
Objects whose gravity field is too strong for light to escape were first
considered in the 18th century by John Michell and Pierre-Simon Laplace.
The first modern solution of general relativity that would characterize a
black hole was found by Karl Schwarzschild in 1916, although its
interpretation as a region of space from which nothing can escape was
not fully appreciated for another four decades. Long considered a
mathematical curiosity, it was during the 1960s that theoretical work
showed black holes were a generic prediction of general relativity. The
discovery of neutron stars sparked interest in gravitationally collapsed
compact objects as a possible astrophysical reality.
Black holes of stellar mass are expected to form when very massive stars
collapse at the end of their life cycle. After a black hole has formed it can
continue to grow by absorbing mass from its surroundings. By absorbing
other stars and merging with other black holes, supermassive black holes
of millions of solar masses may form. There is general consensus that
supermassive black holes exist in the centers of most galaxies
Despite its invisible interior, the presence of a black hole can be inferred
through its interaction with other matter and with electromagnetic
radiation such as light. Matter falling onto a black hole can form an
accretion disk heated by friction, forming some of the brightest objects in
the universe. If there are other stars orbiting a black hole, their orbit can
be used to determine its mass and location. Material spiraling into a black
hole emits xrays. These data can be used to exclude possible alternatives
such as neutron stars. In this way, astronomers have identified numerous
stellar black hole candidates in binary systems, and established that the
core of our Milky Way galaxy contains a supermassive black hole of about
4.3 million solar masses.
NOW: Complete the statements to the right
STEP III
Find and circle you answers on the grid below. Note: Words can read in any
direction.
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STEP IV - Now read left to right, row by row, the letters you have not circled for a
hidden message about the work sheet topic. Write it here:
________________________________________________________________
________________________________________________________________
STEP II
Write in the missing word to complete the statements below.
1.
Black holes of stellar mass are expected to form when
very ___________________ stars collapse at the end of
their life cycle.
2. Despite its _______________________ interior, the
presence of a black hole can be inferred through its
interaction with other matter
3. The discovery of ______________________ stars sparked
interest in gravitationally collapsed compact objects as a
possible astrophysical reality.
4. A black hole is a region of ______________________ from
which gravity prevents anything, including light, from
escaping.
5. Material spiraling into a black hole emits _____________.
6. Matter falling onto a black hole can form an
______________________ disk heated by friction
7. Astronomers established that the core of our Milky Way
galaxy contains a ________________________ black hole
8. The theory of general ________________ predicted that
black holes where possible.
9. Objects whose __________________ field is too strong
for light to escape were first considered in the 18th
century.
10. What is the name of our galaxy ____________ _________
11. Around a black hole there is a mathematically defined
surface called an ______________ horizon that marks the
point of no return
12. After a black hole has formed it can continue to grow by
________________________ mass from its surroundings.
13. If there are other stars orbiting a black hole, their orbit
can be used to determine its _____________ and location