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[[Image:Roger_Federer.jpg|thumb|left|{{#ifexist:Template:Roger Federer.jpg/credit|{{Roger Federer.jpg/credit}}<br/>|}}Roger Federer, a professional tennis player, hitting a forehand against James Blake in the quarterfinals of the 2006 U.S. Open.]]
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<small>
'''[[Tennis]]''' is a sport played between either two players ("singles") or two teams of two players ("doubles"). Players use a stringed racquet to strike a hollow rubber ball covered with felt over a net into the opponent's court. In some places tennis is still called '''lawn tennis''' to distinguish it from ''real tennis'' (also known as ''royal tennis'' or ''court tennis''), an older form of the game that originated in France in the Middle Ages and is played indoors on a very different court. Originating in England in the late nineteenth century, lawn tennis first spread throughout the English-speaking world, particularly among the upper classes. Today tennis is an Olympic sport that is played at all levels of society, by all ages, and in many countries around the world.  Except for the adoption of the tie-breaker in the 1970s, its rules have remained remarkably unchanged since the 1890s.  Millions of people also follow tennis as a spectator sport, especially the four Grand Slam tournaments.
==Footnotes==
 
{{reflist|2}}
===Manner of play===
</small>
====The court====
Tennis is played on a rectangular, flat surface that can be composed of various materials.  The court is 78 feet (23.77 meters) long and its width is 27 feet (8.23 m) for singles matches and 36 feet (10.97 m) for doubles matches. Additional clear space around the court is required in order for players to reach balls. A net is stretched across the full width of the court, parallel with the baselines, dividing it into two equal areas. The net is 3 feet 6 inches (1.07 m) high at the posts and 3 feet (914 mm) high in the center.
 
=====''The lines''=====
The two lines that delineate the width of the court are called the baseline.  The short mark in the center of each baseline is referred to as either the hash mark or the center mark.  The outermost lines that make up the length are both called the doubles sideline.  These are the boundaries used when doubles is being played.  The area between the doubles sideline and the lines next to them is called the doubles alley, which is considered to be "out" in singles play.  These lines next to the doubles sideline are the singles sidelines, and are used as boundaries in singles play.  The line that runs across the center of a player's side of the court is called the service line; despite its name this is not where a player legally stands when making a serve.  The line dividing the service line in two is called the center line or center service line.  The boxes that this center line creates are called the service boxes; depending on a player's position, they will have to hit the ball into one of these when serving.
 
[[Tennis|.....]]

Latest revision as of 09:19, 11 September 2020

After decades of failure to slow the rising global consumption of coal, oil and gas,[1] many countries have proceeded as of 2024 to reconsider nuclear power in order to lower the demand for fossil fuels.[2] Wind and solar power alone, without large-scale storage for these intermittent sources, are unlikely to meet the world's needs for reliable energy.[3][4][5] See Figures 1 and 2 on the magnitude of the world energy challenge.

Nuclear power plants that use nuclear reactors to create electricity could provide the abundant, zero-carbon, dispatchable[6] energy needed for a low-carbon future, but not by simply building more of what we already have. New innovative designs for nuclear reactors are needed to avoid the problems of the past.

(CC) Image: Geoff Russell
Fig.1 Electricity consumption may soon double, mostly from coal-fired power plants in the developing world.[7]

Issues Confronting the Nuclear Industry

New reactor designers have sought to address issues that have prevented the acceptance of nuclear power, including safety, waste management, weapons proliferation, and cost. This article will summarize the questions that have been raised and the criteria that have been established for evaluating these designs. Answers to these questions will be provided by the designers of these reactors in the articles on their designs. Further debate will be provided in the Discussion and the Debate Guide pages of those articles.

Footnotes
  1. ↑ Global Energy Growth by Our World In Data
  2. ↑ Countries, organizations, and public figures that have reconsidered their stance on nuclear power are listed on the External Links tab of this article.
  3. ↑ Pumped storage is currently the most economical way to store electricity, but it requires a large reservoir on a nearby hill or in an abandoned mine. Li-ion battery systems at $500 per KWh are not practical for utility-scale storage. See Energy Storage for a summary of other alternatives.
  4. ↑ Utilities that include wind and solar power in their grid must have non-intermittent generating capacity (typically fossil fuels) to handle maximum demand for several days. They can save on fuel, but the cost of the plant is the same with or without intermittent sources.
  5. ↑ Mark Jacobson believes that long-distance transmission lines can provide an alternative to costly storage. See the bibliography for more on this proposal and the critique by Christopher Clack.
  6. ↑ "Load following" is the term used by utilities, and is important when there is a lot of wind and solar on the grid. Some reactors are not able to do this.
  7. ↑ Fig.1.3 in Devanney "Why Nuclear Power has been a Flop"

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