28. Why has the tomb of Qin Shi Huangdi not been opened yet?

The tomb of Qin Shi Huangdi, the first emperor of China, has not been opened for several reasons:

1. **Preservation Concerns**: The tomb complex is believed to contain a vast array of artifacts and treasures, including Terracotta Warriors. Researchers are concerned that opening the tomb might expose these items to air, which could lead to deterioration.

2. **Historical and Cultural Significance**: The tomb is considered a national treasure and holds immense historical and cultural importance for China. There is a desire to respect and preserve this heritage.

3. **Scientific and Archaeological Challenges**: There are uncertainties about the tomb's condition and structure. Archaeologists are wary of potential hazards, such as collapsing tunnels or unstable environments.

4. **Ethical Considerations**: Ethical debates surround the excavation of burial sites. Many believe it is important to respect the final resting places of historical figures.

5. **Government and Institutional Policies**: The Chinese government may have policies in place regarding the excavation and study of ancient sites, prioritizing preservation and careful study over excavation.

6. **Lack of Comprehensive Planning**: There is a need for thorough research and planning before any excavation. As of now, there may not be sufficient understanding of the tomb's layout or the best methods for excavation.

Overall, while there is immense interest in the tomb and its potential discoveries, these factors contribute to the decision to keep it sealed for the time being.