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  • 科学模型

    Cyclists ride along a road with snow-capped mountains in the background.

     

    Why do scientists need models?
    ::为什么科学家需要模型?

    Scientists work with models because reality is complex and difficult. Earth's  climate  is an example of a system that is both difficult and complex. Many factors influence climate:  ,  snow  cover, ocean mixing, sequestration of carbon in the oceans, etc. In  fact , there are many more factors than can be dealt with all at once. Models are necessary in  science . However, you must always remember that a  model  is a model and not the real thing.
    ::科学家与模型合作是因为现实是复杂和困难的。地球的气候是一个既困难又复杂的系统的例子。许多因素影响气候:雪盖、海洋混合、海洋碳固存等。事实上,还有很多因素不能同时解决。模型在科学中是必要的。然而,你必须永远记住模型是一个模型,而不是真正的模型。

    Models are Useful Tools
    ::模型是有用的工具

     are useful tools for scientists. Most of Earth's systems are extremely complex. Models allow scientists to work with systems that are nearly impossible to study as a whole. Models help scientists to understand these systems. They can analyze and make predictions about them using the models. There are different types of models.
    ::模型可以帮助科学家理解这些系统。他们可以用模型来分析和预测这些系统。有各种不同的模型。

    • Physical models are smaller and simpler representations of the thing being studied. A globe or a   is a  physical model  of a portion or all of Earth.
      ::物理模型对所研究的物体的描述较小、简单。地球或地球的某一部分或整个地球的物理模型是地球的某一部分或整个地球的物理模型。
    • Conceptual models tie together many ideas to explain a phenomenon or event.
      ::概念模型将许多想法联系在一起,以解释一种现象或事件。
    • Mathematical models are sets of equations that take into account many factors to represent a phenomenon. Mathematical models are usually done on computers.
      ::数学模型是考虑到多种因素以体现一种现象的方程组合,数学模型通常在计算机上制作。

    Many models are created on computers ( Figure   ). Only computers can handle and manipulate such enormous amounts of  data . Many scientists now work with climate models. An unimaginable number of factors affect Earth’s climate. Many factors are dependent on one another. A reasonably accurate climate model needs the most powerful computers. Still, no computer has yet been developed that can work with the entire system. So scientists create models that represent parts of the system.
    ::许多模型都是在计算机上创建的(图 ) 。 只有计算机才能处理和操作如此庞大的数据。 许多科学家现在都与气候模型合作。 无法想象的诸多因素影响着地球气候。 许多因素彼此依赖。 一个相当准确的气候模型需要最强大的计算机。 尽管如此,还没有开发出能够与整个系统合作的计算机。 因此科学家创造了代表系统部分内容的模型。

    A workspace with multiple computers used for scientific modeling and analysis.

     

    Many scientists use computers to model complicated processes.
    ::许多科学家利用计算机来模拟复杂的过程。

    Models Can be Used to Test Ideas
    ::模型可用于测试概念

    Scientists must test their ideas. It's much easier to work with a model than with a whole system. A scientist may want to understand how rising CO 2  levels will affect climate. In this case, it will be easier to model a smaller portion of that system. For example, the scientist may model how higher levels of CO 2  affect plant growth and the effect that will have on climate.
    ::科学家必须测试他们的想法。 使用模型比使用整个系统更容易得多。 科学家也许想了解二氧化碳水平的上升会如何影响气候。 在这种情况下,将更容易模拟这个系统中的一小部分。 比如, 科学家可以模拟二氧化碳水平的升高会如何影响植物生长和对气候的影响。

    Models Can be Used to Make Predictions
    ::模型可用于预测

    Models can be used to predict the future. The best ones take into account the most factors. How do scientists know if a model will predict the future accurately? One way is to use a time in the past as the starting point. Then run the model to see if the model can accurately predict the present. A model that can successfully predict the present is more likely to be better at predicting the future. For example, climate models are very useful for trying to determine what types of changes we can expect as carbon dioxide in the  atmosphere  rises.
    ::模型可以用来预测未来。 最好的模型可以考虑到大多数因素。 科学家如何知道模型是否准确预测未来? 一种方法是利用过去的时间作为起点。 然后运行模型看模型能否准确预测现在。 能够成功预测现在的模型在预测未来方面更有可能更好。 例如,气候模型非常有助于确定随着大气二氧化碳的上升,我们预期会发生何种变化。

    Models Have Limitations
    ::具有局限性的模型

    Since models are simpler than real objects or systems, they have limitations. A model deals with only a portion of a system. It may not predict the behavior of the real system very accurately. But the more computing power that goes into the model and the care with which the scientists construct the model can increase the chances that a model will be accurate.
    ::由于模型比真实物体或系统简单,因此它们有局限性。模型只涉及系统的一部分。它可能无法非常准确地预测实际系统的行为。但是,进入模型的计算能力越多,科学家越小心地构建模型,模型就越有可能准确。

    Summary
    ::摘要

    • A model is a representation of a more complex system. Models can be manipulated more easily than the system.
      ::模型代表一个更复杂的系统,模型比系统更容易被操纵。
    • Models can be used to make predictions.
      ::模型可用于作出预测。
    • Models may be physical, conceptual, or mathematical.
      ::模型可以是物理模型、概念模型或数学模型。

    Review
    ::回顾

    1. Why do scientists use models?
      ::科学家为什么使用模型?
    1. Describe the types of models mentioned.
      ::描述所提到的模型类型。
    1. Why are computers often used to make models?
      ::为什么计算机经常被用来制造模型?

    Explore More
    ::探索更多

    Use the resource below to answer the questions that follow.
    ::利用以下资源回答以下问题。

    1. What is a model?
      ::什么是模型?
    1. How do scientists create models?
      ::科学家如何创造模型?
    1. How are models checked for accuracy?
      ::如何检查模型的准确性?
    1. How did Dr. Hansen check his model?
      ::汉森医生是怎么检查他的模特的?
    1. What are the challenges associated with modeling?
      ::与建模相关的挑战是什么?