Yǔzhòu shì bu shì wúqióngdà, zhìjīn réng shì ge mí.
Whether the universe is infinitely large is still a mystery.
Tips
usage
无穷大 is the mathematical term — it pairs with 无穷小 (wúqióngxiǎo, infinitesimal). For 'endless' in everyday speech, 无穷 alone or 无限 (wúxiàn) is more common.
memory
Read it literally: 'no end big' = 'no end to its bigness' = infinity (∞).
