Our Cosmic Roots

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Today, I responded with answers (A) to the following questions (Q):

Q: What do you see as the most consequential uncertainty in our understanding of the first stars and galaxies, and how can observations of the early universe help distinguish between competing accounts of how the first sources of light transformed the cosmos?

A: The most exciting question is how early did the first stars form after the Big Bang. Their formation marks the transition of the Universe into complexity from the simple initial conditions that can be summarized on a single sheet of paper (in terms of the matter constituents [dark matter and ordinary matter] and the power-spectrum of primordial density fluctuations on smaller scales than were probed so far). The first stars also mark the beginning of the productions of Carbon, Oxygen, Nitrogen, Phosphorus and Sulphur, elements that are essential for the chemistry of life-as-we-know-it. They represent our cosmic roots and the scientific version of the biblical phrase “Let there be light!”

About 15 million years after the Big Bang (or equivalently, a redshift of about z=110), the cosmic background radiation had room temperature. If Earth-like planets had existed at that time, they would have not needed to be close to stars in order for their surface to be warmed to habitable conditions. The popular cosmological model predicts that the first stars form 50 million years later (redshift of z~50). But we need to check if that is indeed the case. I discussed this in 2014 in a paper titled “The Habitable Epoch of the Universe” here, and discussed the broader context in two follow-up papers here and here.

There are several observational signatures that can reveal the answer. The first stars were massive and could have resulted in gamma-ray bursts when they collapsed to black holes. Also, mergers of black holes could be detected by future gravitational-wave observatories. Finally, the Webb telescope and its followers could keep pushing the earliest galaxies on record.

Q: What are your biggest challenges right now? Is it visibility, finding the right audience, getting your books to more readers, sales, or something I haven’t thought of?

A: My research focus changed over the years from the first stars to the study of black holes and recently to the search for alien intelligence. My biggest challenge right now is to discover evidence for alien intelligence. Such a discovery will be more impactful on the future of humanity than artificial intelligence (AI) because alien intelligence is likely to reflect a much bigger database than the terrestrial information used to train AI in our data centers. Most of the real estate is beyond Earth.

We are probably not at the top of the cosmic food chain and we can learn from our most accomplished counterparts. Most of the stars formed billions of years before the Sun and it will take only of order a billion years for Voyager to cross the Milky Way disk relative to the Sun. Alien probes therefore had enough time to reach us even if they used our rocket technology from the 1970s. There are of order tens of billions of Earth-Sun analogs in the Milky-Way alone. Given so many houses in our cosmic street, common sense suggests that we are not alone and many of them had residents because similar circumstances should lead to similar outcomes. Astrobiologists focus on investing more than ten billion dollars over the next two decades in searching for the chemical fingerprints of microbes. But I say that on a blind date with a cosmic partner, we should aim high rather than low. Instead of seeking abundant and mediocre dating partners like microbes, we should search for someone more intelligent than we are. The practical benefit (as in the case of my search for a wife) is that a smarter counterpart can inspire us to do better.

Think of me as a curious kid, not willing to believe in stories from the adults in the room but rather interested in finding the truth based on evidence. Life can be a self-fulfilling prophecy. Without engaging in the correct search strategy, we will never find anything.

Some people who worked in the U.S. government claim that it has an alien spacecraft in its possession. To them I say: take me to the nearest alien spacecraft!

If a functioning spacecraft is parked on Earth and I am offered a seat on it, I will be first in line to board the spacecraft on a trip to an alien world. I would have no regret leaving Earth towards the stars based on my news feed on current events in our world.

Q: When something unusual turns up in the data, what does it take for you to say it’s technological rather than natural?

A: When faced with anomalous objects, I sometimes feel like the kid in Hans-Christian Andersen’s tale being told by the adults in the room: “The Emperor has clothes but they are invisible.” For example, the first interstellar object, 1I/`Oumuamua, showed non-gravitational acceleration but no coma of outgassing around it. Comet experts now label it as a dark comet, where the cometary tail is invisible. That this is endorsed as a mainstream view demonstrates that scientists do not always follow evidence. More often, they come up with excuses why the evidence is lacking. I discussed this in the context of another example: supersymmetry, in a recent essay posted here.

Regarding the signature of alien technology: with good enough data, the distinction is straightforward. Here are two examples:

1. An interstellar object showing maneuvering towards Earth that cannot be explained by gravity or cometary outgassing. Similarly, regarding the emission of an electromagnetic signal that cannot be natural in origin. Also, if we get a high-resolution image of it, one can discern whether it looks like a natural rock or iceberg or whether it appears to look like an artificially manufactured object.

2. An Unidentified Anomalous Object (UAP) in the Earth’s atmosphere or oceans, which is documented to behave outside the performance envelopes of human-made technologies. Of course, if any such object was retrieved and is currently in possession of the U.S. government or a Corporation like Lockheed Martin, it would be straightforward to infer whether its isotopic composition implies an origin from outside the Solar System, whether the material structure was manufactured artificially or whether the object functions in ways that exceed human products by a large margin.

Finding residents in our cosmic neighborhood could shed light on our cosmic origins story. It started simple for the first 100 million years after the Big Bang and became much more interesting 13.8 billion years later, with many intricate details waiting to be unraveled. Pretending to be the elders in the cosmos is unreasonable. We better explore the unknown with a child’s wonder. I do not pretend to do more than that.

Professional website:

https://lweb.cfa.harvard.edu/~loeb/

https://avi-loeb.medium.com/ https://www.youtube.com/@ProfessorAviLoeb

https://open.spotify.com/show/1zhndXkvSY2b8FdjspFpCd https://x.com/ProfAviLoeb
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今天，我对以下问题（Q）作出了回答（A）：

问：您认为我们对第一批恒星和星系的理解中，最关键的不确定性是什么？对早期宇宙的观测如何帮助我们区分关于第一批光源如何改变宇宙的各种相互竞争的说法？

答：最令人兴奋的问题是，第一批恒星是什么时候形成的。大爆炸之后，它们的形成标志着宇宙从最初可以用一张纸概括的简单状态（仅能概括物质组成[暗物质和普通物质]以及比目前探测到的尺度更小的原始密度涨落功率谱）过渡到复杂的状态。第一批恒星也标志着宇宙物质生产的开始。碳、氧、氮、磷和硫这几种元素，是构成我们所知生命化学体系的必要元素。它们代表着我们的宇宙根源，也是圣经中“要有光！”这句格言的科学版本。

大约在大爆炸后1500万年（或者等效地，红移约为z=110），宇宙背景辐射的温度与室温相当。如果类地行星的温度与地球相当，那么地球周围的宇宙空间就会变得非常有限。如果当时存在这样的天体，它们无需靠近恒星，表面温度就能达到适宜居住的程度。目前流行的宇宙学模型预测，第一批恒星会在5000万年后形成（红移z~50）。但我们需要验证这一预测是否正确。我在2014年发表的一篇题​​为《宇宙宜居时期》的论文中讨论过这个问题，该论文也探讨了……后续两篇论文对此进行了更详细的阐述（见此处和此处）。

有几个观测特征可以揭示答案。第一批恒星质量巨大，它们坍缩成黑洞时可能产生了伽马射线暴。此外，未来的引力波天文台可以探测到黑洞合并事件。最后，韦伯太空望远镜及其后续望远镜可以不断推动早期黑洞的演化。有记录的t个星系。

问：您目前面临的最大挑战是什么？是提高知名度、找到合适的受众、让更多读者看到您的书、提高销量，还是我没想到的其他问题？

答：这些年来，我的研究重点从最早的恒星研究转向黑洞研究，最近又转向寻找外星智慧生命。目前我面临的最大挑战是找到外星智慧生命存在的证据。人工智能。这样的发现对人类的未来比人工智能（ AI ）更具影响力，因为外星智能可能反映的数据库比我们数据中心用于训练AI的地面信息大得多。 大部分房地产都在地球之外。

我们可能没有处于宇宙食物链的顶端，我们可以从我们的最大成就中学习类似的恒星。大多数恒星形成于太阳形成数十亿年前，而旅行者号探测器相对于太阳穿越银河系盘面也只需要大约十亿年。因此，即使外星探测器使用我们上世纪70年代的火箭技术，也有足够的时间到达地球。仅在银河系中就有数百亿颗类似地球和太阳的恒星。考虑到我们宇宙中如此多的恒星，从宇宙街道的角度来看，常识告诉我们，我们并不孤单，而且许多宇宙街道都曾有居民，因为相似的环境应该会导致相似的结果。天体生物学家致力于在未来二十年投入超过一百亿美元，寻找微生物的化学指纹。但我认为，在与宇宙伴侣的“盲约”中，我们应该志存高远，而不是安于现状。与其像微生物一样寻找数量众多但水平平庸的约会对象，我们应该寻找比我们更聪明的人。这样做的实际好处（就像我寻找妻子一样）在于，更聪明的伴侣可以激励我们做得更好。

请把我当成一个好奇的孩子，不愿轻易相信大人讲述的故事，而是更倾向于根据证据探寻真相。这可能是一种自我实现的预言。如果不采用正确的搜索策略，我们将一无所获。

一些曾在美国政府工作的人声称，美国政府拥有一艘外星飞船。对此，我想说：带我去最近的外星飞船那里！

如果一艘功能完好的宇宙飞船停泊在地球上，并且有人邀请我登船，我将第一个排队登船。去外星世界旅行。根据我目前了解到的全球时事，我丝毫不会后悔离开地球，奔向星辰大海。

问：当数据中出现不寻常的情况时，您需要满足什么条件才能判断它是技术性的而不是自然性的？

A：面对异常物品时，我有时感觉自己就像安徒生童话故事里被大人讲故事的小孩一样。“皇帝的新衣只是隐形的。”例如，第一颗星际天体1I/奥陌陌（Oumuamua）展现出非引力加速度，但周围却没有彗发或气体逸出。彗星专家现在将其称为暗彗星，因为彗尾不可见。这种观点被主流接受，表明科学家并非总是遵循证据。更多时候，他们会提出……这为证据不足找了借口。我曾在最近发表于此的一篇文章中，以超对称性为例讨论过这个问题。

关于外星科技的特征：只要数据足够可靠，区分起来就很简单。以下是两个例子：

1. 一个星际天体表现出向地球移动的趋势，而这种趋势无法用引力或彗星喷发来解释。同样地，检测不可能是自然产生的电磁信号的发射。此外，如果我们获得它的高分辨率图像，就可以分辨它看起来像天然岩石或冰山，还是像人造物体。

2. 地球大气层或海洋中出现的不明异常物体（UAP），其行为已被记录在案，且超出预期范围。人造技术的外壳。当然，如果此类物体被回收并目前由美国政府或像洛克希德·马丁公司这样的企业持有，那么很容易推断其同位素组成是否表明其起源于太阳系之外，其物质结构是否为人工制造，或者该物体的功能是否与太阳系有关。远超人类产品。

在我们的宇宙邻里中寻找居民，或许能揭开我们宇宙起源的秘密。宇宙大爆炸后的最初一亿年，一切都很简单；而到了138亿年后，宇宙变得精彩纷呈，许多错综复杂的细节等待我们去探索。自诩为宇宙的“长老”是不明智的。我们更应该勇于探索未知。带着孩童般的好奇心。我并不妄称自己能做到更多。

专业网站：

https://lweb.cfa.harvard.edu/~loeb/

https://avi-loeb.medium.com/ https://www.youtube.com/@ProfessorAviLoeb

https://open.spotify.com/show/1zhndXkvSY2b8FdjspFpCd https://x.com/ProfAviLoeb
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原文链接：https://avi-loeb.medium.com/our-cosmic- ... ad3f9b2886
作者：Avi Loeb（哈佛大学天文系教授）