If You Could Watch a Time-Lapse Movie of the Interstellar

question 37

Multiple Choice

If you could watch a time-lapse movie of the interstellar medium over hundreds of millions of years,what would you see?

• A)Gas that changes only in very slow and steady ways,so that the movie would in fact be quite boring.
• B)The entire disk of the Milky Way would pulsate in and out as it contracts to form stars and then blows out in supernovae and then contracts to form stars again and so on.
• C)The movie would alternate back and forth between being very bright when there is a lot of gas and very dark when there is very little gas.
• D)Gas that is often moving at high speed,particularly after one or more supernovae,and constantly changing form between molecular clouds,atomic hydrogen,and hot,ionized bubbles and superbubbles.

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Definitions:

Net Present Value

The difference between the present value of cash inflows and the present value of cash outflows over a period of time, used in capital budgeting to assess the profitability of investments.

Manufacturing Machinery

The equipment and machines used in the process of producing goods in manufacturing facilities.

Future Cash Flows

Estimates of future financial transactions that involve the inflow or outflow of money from a particular operation or investment.

Present Value

The current worth of a future sum of money or stream of cash flow given a specified rate of return.