Every Wednesday, Michio Kaku will be answering reader questions about physics and futuristic science. If you have a question for Dr. Kaku, just post it in the comments section below and check back on Wednesdays to see if he answers it.

Today, Dr. Kaku addresses a question posed by Sassan K. Darian: What are the practical applications of cryogenics today, and what potential improvements can we expect 20 to 30 years down the line?