Much has （or has not） happened in the seven years or so since the publication of the first edition of this book. Most notably， a new spin-0 particle with mass~125 GeV was discovered at the LHC by the ATLAS and CMS collaborations， which is either the elementary Higgs boson or something that closely resembles it. The Higgs discovery completes the ≥40 year saga of verifying the standard model （SM）. Moreover， its mass is almost maximally interesting： it is near the top of the range predicted by the most popular SM extension，minimal supersymmetry， and near the minimum value consistent with the unextended SM （and then only if the vacuum is metastable）！However， the notorious problems of the SM are still unresolved. Perhaps the most press-ing is the apparently fine-tuned hierarchy between the weak interaction and gravity scales.Extensive searches at the LHC and elsewhere have so far not yielded any compelling evidence for new TeV-scale physics such as supersymmetry， extra space dimensions， or strong cou-pling that had been proposed to explain or at least stabilize the hierarchy. Equally puzzling is the nature of the dark energy and its incredibly tiny magnitude compared to most theo-retical expectations. Similarly， numerous experimental attempts to identify the mysterious dark matter inferred from its gravitational effects have not as yet had any positive results and have excluded much of the parameter space for supersymmetric dark matter. And de-spite the great experimental success of the SM， it is a very complicated theory， involving severalinteractions with different properties， and two apparently superfl.uous heavier copies of the fundamental particles that constitute ordinary matter under ordinary conditions. For these and other reasons， many theorists have started exploring less canonical possibilities，such as a dark matter sector that is at most very weakly coupled to ordinary particles，or， more radically， that the Universe is part of a vast multiverse of regions （presumably associated with a superstring landscape of vacua with different laws of physics.

　　保羅·蘭蓋克 （Paul Langacker），美國(guó)物理學(xué)家，賓夕法尼亞大學(xué)物理與天文系榮休教授，并曾擔(dān)任系主任，他還是普林斯頓高等研究院的長(zhǎng)期客座研究員。他的研究強(qiáng)調(diào)基礎(chǔ)理論和實(shí)驗(yàn)之間的聯(lián)系，包括精密電弱物理、大統(tǒng)一理論、中微子物理、Z'物理和弦唯象學(xué)等。他是美國(guó)物理學(xué)會(huì)（APS）和美國(guó)科學(xué)促進(jìn)會(huì)（AAAS）的杰出會(huì)士。