| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
Fiscal Year 2020: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2019: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
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| Outline of Final Research Achievements |
We study nonlinear waves in the Friedmann-Lemaitre-Robertson-Walker spacetime, known as the standard cosmological model. The aim of this study is to elucidate the effect of the scale factor, representing the expansion rate of the universe, on nonlinear waves by comparing with known results in flat spacetime, such as the Minkowski spacetime. We classify the expanding universe model into decelerating, constant,and accelerating cases, and determine the global existence conditions, blow-up conditions, and estimates for the lifespan of blow-up solutions of the nonlinear wave equation. As a result, it is revealed that blow-up of solutions is more likely to occur compared to the Minkowski spacetime case, and furthermore, the lifespan of blow-up solutions is shorter.
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