Briefly on BH Information Paradox & ‘Soft Hair’ and elaborately on his WARNINGS

We have our member Adhitya Shreyas SP, to summarize Hawking’s final paper.

SRM Astrophilia
SRM Astrophilia


It was on Dec 13, 2018, that a paper entitled ‘Black Hole Entropy and Soft Hair’ was uploaded on ArXiv. Although Stephen Hawking didn’t stand as its first author, this paper marks fame accounting from the celebrity culture and most importantly — because Hawking was dead already!

I, Adhitya Shreyas SP, showcase a short light pulse on what encompassed in his last paper. Later, I propound his concerns towards where humanity is proceeding.

This paper is essentially a ‘review paper’ which Hawking co-authored with Sasha Haco, Malcolm Perry, and Andrew Strominger. This work addresses the black hole information paradox, which he formalized years back. He said that black holes — by compressing matter and energy into an infinitely dense singularity — create seemingly insurmountable information paradox. Like many other physics conundrums, this paradox emerges from the lack of coherence between quantum theory and classical theory (general relativity)*. One assertion of the paradox is that the information could permanently disappear within the volume of the BH, allowing many physical states to devolve into the same state. The famous ‘Hawking Radiation’ comes out under the same argument where he asserts that this information is indeed be deleted from the BH via physical radiations.

Hawking and his colleagues introduced a model with the keyword ‘soft hair’, that might withhold the black hole information paradox. The idea is that trails of photons encircle the event horizon, and store enormous entropic information about the matter that falls into the black hole. This goes as follows. (1) Falling object increases the temperature of the Black Hole. (2) This temperature change causes the entropy to change. Hawking shows in ‘ Hawking-Bekenstein formula’ that (3) entropy is related to the Black Hole surface area. Hence, (4) the photons at the horizon record the dynamical information happening within the Black Hole volume. They call this sheen of photons “soft hair”.

*As a side note, let me tell you that Hawking is considered to be the first physicist to take advantages of quantum theory in classical fields.

Stephen Hawking

Hawking’s left us with his speeches encompassing valuable warnings, which — from him- are justified as ‘nervous concerns of a celeb philosopher’.

1. Humanity is on a path to either disaster or the stars

“Although the chance of a disaster on planet Earth in a given year may be quite low, it adds up over time, becoming a near certainty in the next thousand or ten thousand years”.

We see Hawking predicts that our destiny is to become a space-faring species. “By that time, we should have spread out into space, and to other stars, so it would not mean the end of the human race … however, we will not establish self-sustaining colonies in space for at least the next hundred years, so we have to be very careful in this period”. Hawking’s fears over the risk’s human planetary migration are not new. In this century, he’s spoken critically about where developments such as nuclear weapons and genetically engineered viruses may be leading us. “Science and technology are changing our world dramatically, so it’s important to ensure that these changes are heading in the right directions … in a democratic society, this means that everyone needs to have a basic understanding of science, to make informed decisions about the future.”

2. We need to get up and move around a little more

Hawking made his mark in science by studying things with enormous masses — black holes. Guess what, he also spoke about obesity too.

“Today too many people die from complications related to overweight and obesity”.

Hawking said this in an advertisement promoting a Swedish non-profit company called GEN-PEP. “We eat too much and move too little.” Mobility for half-an-hour or so must be desirable. “It’s not rocket science,” Hawking claimed.

3. Artificial intelligence will replace us all

Stephen Hawking fears it may only be a matter of time before humanity is forced to flee Earth in search of a new home.

“If people design computer viruses, someone will design AI that improves and replicates itself … this will be a new form of life that outperforms humans.”

4. Aliens probably won’t want to be our best friends

While we’re keeping trim, working on our environmental problems, keeping AI relatively unintelligent, and putting our feet on Mars, we should also try to keep quiet. Hawking was convinced aliens were out there somewhere.

“If so, they will be vastly more powerful and may not see us as any more valuable than we see bacteria”.

5. We’re in The Middle of a “Global Revolt Against Experts”

With fake news becoming big news, Hawking responded to questions on the state of the media by encouraging us to listen to the advice of those who devote their time to study problems. Hawking was referring to environmental challenges such as deforestation and climate change, and the unwillingness of many world leaders and members of the public to follow the advice of scientists.

We wish Adhitya best for his career in science delivering, and hope that he keeps on inspiring his audience.