Final answer:
Scientific ideas are always open to change as scientists test and revise their ideas based on new observations and discoveries. Existing ideas are often revised rather than completely replaced. Through many new discoveries over time, scientists build a more accurate understanding of the natural world. Occasionally, there may be radical changes in scientific understanding, known as paradigm shifts.
Step-by-step explanation:
Scientific ideas are always open to change. Scientists continually test and revise their ideas based on new observations and discoveries. While some ideas may be replaced with new ones that better fit the facts, more often, existing ideas are simply revised. Through many new discoveries over time, scientists gradually build an increasingly accurate and detailed understanding of the natural world. Occasionally, there may be radical changes in scientific understanding, known as paradigm shifts, which occur when new ideas completely replace existing ones.